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1
Wang, Shaojun, and Joe Eaton. "Predicting Productivity Index of Horizontal Wells." Journal of Energy Resources Technology 129, no. 2 (November 2, 2006): 89–95. http://dx.doi.org/10.1115/1.2718577.
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The popular Joshi model slightly overestimated the flow resistance of a horizontal well. As a result of this, the Joshi model underpredicts the productivity index (PI) of a horizontal well by a few percent. In the extreme case in which vertical permeability goes to zero, the Joshi model predicts a 0.0 stb∕day-psi PI, which is wrong. In this paper, the flow for a horizontal well is divided into three flows: the flow in the reservoir above the horizontal wellbore, the flow in the reservoir with a thickness of 2rw containing the horizontal wellbore, and a flow in the reservoir below the horizontal well bore. The second flow is assumed to be pure horizontal flow. The first and third flows can be further divided into a horizontal flow and a vertical flow. In this paper, the equation for each flow is provided, and then combining these flows we give the equation to calculate the effective PI of horizontal wells. In addition, when the horizontal wellbore is not located at the h∕2 midpoint of a reservoir, the Joshi model predicts an increasing PI, which is intuitively and mathematically an incorrect trend. This paper derives a new equation to compute the PI of horizontal wells when the wellbore is eccentric relative to the reservoir midpoint. The new equation generates the correct trend.
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Aulisa, Eugenio, Lidia Bloshanskaya, and Akif Ibragimov. "Well productivity index for compressible fluids and gases." Evolution Equations and Control Theory 5, no. 1 (March 2016): 1–36. http://dx.doi.org/10.3934/eect.2016.5.1.
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Wang, Mingxian, Zifei Fan, Lun Zhao, Guoqiang Xing, Wenqi Zhao, and Chengqian Tan. "Productivity analysis for a horizontal well with multiple reorientation fractures in an anisotropic reservoir." Oil & Gas Science and Technology – Revue d’IFP Energies nouvelles 75 (2020): 80. http://dx.doi.org/10.2516/ogst/2020078.
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Reorientation fractures may be formed in soft and shallow formations during fracturing stimulation and then affect well productivity. The principal focus of this study is on the productivity analysis for a horizontal well with multiple reorientation fractures in an anisotropic reservoir. Combining the nodal analysis technique and fracture-wing method, a semi-analytical model for a horizontal well with multiple finite-conductivity reorientation fractures was established to calculate its dimensionless productivity index and derivative for production evaluation. A classic case in the literature was selected to verify the accuracy of our semi-analytical solution and the verification indicates this new solution is reliable. Results show that for a fixed fracture configuration the dimensionless productivity index of the proposed model first goes up and then remains constant with the increase of fracture conductivity, and optimal fracture conductivity can be determined on derivative curves. Strong permeability anisotropy is a negative factor for well production and the productivity index gradually decreases with the increase of anisotropic factor. As principal fracture angle goes up, horizontal well’s productivity index increases correspondingly. However, the effect of reoriented fracture angle on the productivity index is not as strong as that of principal fracture angle. When reoriented fracture angle is smaller than principal fracture angle, reoriented factor should be as low as possible to achieve optimal productivity index. Meanwhile, well productivity index rises up with the increase of fracture number and fracture spacing, but the horizontal well has optimal reorientation fracture number and fracture spacing to get the economical productivity. Furthermore, the influence of the rotation of one central reorientation fracture on productivity index is weaker than that caused by the rotation of one external reorientation fracture. In addition, the asymmetrical distribution of one or more reorientation fractures slightly affects the productivity index when fracture conductivity is high enough.
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Abdul Manan, Faid, Muhammad Buce Saleh, I. Nengah Surati Jaya, and Uus Saepul Mukarom. "Algorithm for assessing forest stand productivity index using leaf area index." Indonesian Journal of Electrical Engineering and Computer Science 16, no. 3 (December 1, 2019): 1311. http://dx.doi.org/10.11591/ijeecs.v16.i3.pp1311-1319.
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This paper describes a development of an algorithm for assessing stand productivity by considering the stand variables. Forest stand productivity is one of the crucial information that required to establish the business plan for unit management at the beginning of forest planning activity. The main study objective is to find out the most significant and accurate variable combination to be used for assessing the forest stand productivity, as well as to develop productivity estimation model based on leaf area index. The study found the best stand variable combination in assessing stand productivity were density of poles (X2), volume of commercial tree having diameter at breast height (dbh) 20-40 cm (X16), basal area of commercial tree of dbh >40 cm (X20) with Kappa Accuracy of 90.56% for classifying into 5 stand productivity classes. It was recognized that the examined algorithm provides excellent accuracy of 100% when the stand productivity was classified into only 3 classes. The best model for assessing the stand productivity index with leaf area index is y = 0.6214x - 0.9928 with R2= 0.71, where y is productivity index and x is leaf area index.
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Tzeremes, Panayiotis, and Nickolaos G. Tzeremes. "Productivity in the Hotel Industry: An Order-α Malmquist Productivity Indicator." Journal of Hospitality & Tourism Research 45, no. 1 (November 24, 2020): 133–50. http://dx.doi.org/10.1177/1096348020974419.
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In the literature, it is highlighted that the deterministic nature of the data envelopment analysis–based productivity measures makes them sensitive to sample characteristics. However, the majority of the related empirical studies ignore the potential bias in their data envelopment analysis–based productivity estimations. This article illustrates how the order-α quantile-type estimators can be applied to construct a robust version of the Malmquist productivity indices. Using the order-α estimators, we construct a Malmquist productivity index alongside with two well-known decompositions. The proposed productivity indicator is less sensitive to potential outliers and extreme values. Then, as an illustrative example, we apply the quantile-type productivity index on a sample of 270 hotels operating in the Balearic Islands over the period 2004-2013. The productivity levels alongside with their components are analyzed during the global financial crisis period.
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Oaikhena, E. Emmanuel, and J. Oloro. "A Comparative Study of the Productivity Index of Horizontal Well." Greener Journal of Petroleum and Gas Exploration 1, no. 1 (September 20, 2013): 007–19. http://dx.doi.org/10.15580/gjpge.2013.1.120112308.
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Wang, Shuozhen, Shuoliang Wang, Chunlei Yu, and Haifeng Liu. "Single Well Productivity Prediction Model for Fracture-Vuggy Reservoir Based on Selected Seismic Attributes." Energies 14, no. 14 (July 8, 2021): 4134. http://dx.doi.org/10.3390/en14144134.
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Single well productivity is an important index of oilfield production planning and economic evaluation. Due to fracture-vuggy reservoirs being characteristically strongly heterogeneous and having complex fluid distribution, the commonly used single well productivity prediction methods for fracture-vuggy reservoirs have many problems, such as difficulty in obtaining reservoir parameters and producing large errors in the forecast values of single well productivity. In this paper, based on the triple medium model, the Laplace transform and Duhamel principle are used to obtain the productivity equation of a single well in a fracture-vuggy reservoir. Secondly, the seismic attributes affecting the productivity of a single well are selected using the Spearman and Pearson correlation index calculation method. Finally, the selected seismic attributes are introduced into the productivity equation of the triple medium model through the interporosity flow coefficient and the elastic storativity ratio, and the undetermined coefficients under different karst backgrounds are determined using multiple nonlinear regression. From these, a new method for predicting single well productivity of fracture-vuggy reservoir is established. In order to verify the feasibility of the new method, based on the actual production data of a fracture-vuggy reservoir in Xinjiang, the new single well productivity prediction method is used to predict the productivity of 134 oil wells. The results show that the new productivity prediction method not only reduces calculation workload, but also improves the accuracy of productivity prediction, which contributes to a good foundation for future oilfield development.
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Davletbakova, L. A., S. I. Gabitova, V. Yu Klimov, D. V. Shuvaev, I. Ya Edelman, and S. А. Shmidt. "A new method for monitoring wells productivity index dynamics." PROneft’. Proffessional’no o nefti 6, no. 2 (June 30, 2021): 33–38. http://dx.doi.org/10.51890/2587-7399-2021-6-2-33-38.
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А method for monitoring wells productivity index dynamics from the moment of its start-ups is proposed. It allows detecting candidates for conducting well tests (WT) and well interventions for the increase of a daily production. The method is based on an integral analysis using pressure maps and well tests. Application of this method on the Salym group of oilfields has allowed concluding about wells stock status, about productivity index dynamics in time, also to make an assumption about the reasons for its change. The analysis showed that productivity index relative changes in horizontal wells lower than in slanted wells.
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Nartey, Sarah Beatson, Kofi A. Osei, and Emmanuel Sarpong-Kumankoma. "Bank productivity in Africa." International Journal of Productivity and Performance Management 69, no. 9 (May 23, 2019): 1973–97. http://dx.doi.org/10.1108/ijppm-09-2018-0328.
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Purpose The purpose of this paper is to provide a total factor productivity index for the African banking industry. It also investigates the impact of some internal and external determinants affecting bank productivity. Design/methodology/approach The biennial Malmquist productivity index and various regression models (ordinary least squares, Tobit and truncated bootstrapped regression) are employed in analyzing data from 120 banks in 24 African countries from 2007 to 2012. Findings The results indicate a general decline in productivity of banks in Africa, largely due to inadequate technological progress. State banks are found to be more productive than foreign and private banks. The regression analyses showed that non-executive directors, leverage, management quality, credit risk, competition and exchange rate have significant impact on bank productivity, but ownership and CEO-duality do not. Practical implications The results have implications for management of banks, governments and regulators. It shows the need for policy and investments that improve state-of-the art technology. The findings also seem to suggest poor management practices in input usage, especially in operational management, as well as costs emanating from non-interest sources. Bank managers need to address these deficiencies to improve productivity in African banking markets. Originality/value A major contribution of this paper is the productivity index provided for the African banking industry. This study is also the first to apply the biennial Malmquist to analyze productivity in the African banking industry.
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Naz, Farah, Hafsa Khan, and Madeeha Sayyed. "Productivity and Efficiency Analysis of Pakistani Textile Industry using Malmquist Productivity Index Approach." Journal of Management and Research 4, no. 2 (December 2, 2019): 1–23. http://dx.doi.org/10.29145//jmr/42/040203.
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The key purpose of this study is to evaluate the total factor productivity of the textile sector by using DEA (Data Envelopment Analysis) and also identifying the components which play a significant role in the growth of productivity. This paper examines productivity performance of the Pakistan’s textile manufacturing industry using firm-level panel data of a total of 64 firms for the period 2011-2015. Moreover, the sources of expansion and compression in output are recognized for the whole textile industry as well as for the three sub sectors comprising of 35 firms from spinning, 21 from composite and 8 from weaving textile sector. Empirical results suggest that total factor productivity growth of composite, spinning and weaving textile sectors are not presenting skewed distribution. Moreover, the component of technological change had a negative impact on spinning textile sector. Technical efficiency and technological change, both, had a positive impact on the productivity of composite and weaving textile sectors. Overall, the spinning textile sector has no contribution in the productivity growth. A critical evaluation of the production factors is necessary for the maintenance of the performance of the organization. This paper provides information to the decision makers and policy makers about the allocation, acquisition and anticipation of the resources. To eradicate the industry’s pitfalls, textile sector in combination of subsectors has been selected providing a comparative analysis of the efficiencies adding to the existing body of literature by detecting the primary zones for improving productivity performance in Pakistani textile manufacturing as the pure efficiency component.
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Yuan, Zhiwang, Li Yang, Yingchun Zhang, Rui Duan, Xu Zhang, Yihua Gao, and Baoquan Yang. "Productivity Evaluation for Long Horizontal Well Test in Deep-Water Faulted Sandstone Reservoir." Geofluids 2020 (September 22, 2020): 1–10. http://dx.doi.org/10.1155/2020/8845270.
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For deep-water faulted sandstone reservoirs, the general practice is to design long horizontal wells improving well productivity. During the project implementation stage, well tests are performed on all drilled wells to evaluate well productivity accurately. Furthermore, multisize chokes are often utilized in a shorten test time for loosen formation, high test cost, and high well productivity. Nevertheless, the conventional productivity evaluation approach cannot accurately evaluate the well test productivity and has difficulty in determining the underneath pattern. As a result, the objective of this paper is to determine a productivity evaluation method for multisize chokes long horizontal well test in deep-water faulted sandstone reservoir. This approach introduces a productivity model for long horizontal wells in faulted sandstone reservoir. It also includes the determination of steady-state test time and the productivity evaluation method for multisize chokes. In this paper, the EGINA Oilfield, a deep-water faulted sandstone reservoir, located in West Africa was chosen as the research target. Based on Renard and Dupuy’s steady-state equation, the relationship between the productivity index per meter and the length of horizontal section was derived. Consequently, this relationship is used to determine the productivity pattern for long horizontal wells with the same geological features, which can provide more accurate productivity evaluations for tested wells and forecast the well productivity for untested wells. After implementing this approach on the EGINA Oilfield, the determined relationship is capable to accurately evaluate the test productivity for long horizontal wells in reservoirs with similar characteristics and assist in examination and treatment for horizontal wells with abnormal productivity.
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Jreou, Ghazwan N. S. "Productivity index of horizontal well in Mishrif formation of Buzurgan oil field – Case study." International Review of Applied Sciences and Engineering 12, no. 3 (July 21, 2021): 301–11. http://dx.doi.org/10.1556/1848.2021.00284.
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AbstractHorizontal good technology is one of the recent methods in the drilling and exploitation of geological formations in the best and optimal ways, because of the many and comprehensive advantages that these wells enjoy with the most important measurement and prediction index called productivity index. Which is equivalent to several times higher than the vertical well productivity index, if the field is invested by drilling vertical wells only.The current research focuses on calculating the productivity index by proposing the development point of view of the reservoir formation in the Burgan oil field through the production of oil from the production units approved in the formation (MB21, MC1, MC2) by using of horizontal good technology and comparing it with the value of the productivity index of vertical wells in the same production units.Well-known published methods adopted in the case of steady state and pseudo steady state were used in the calculations of the productivity index, and by comparison with the standard observed results, it was found that the Joshi method was closer than others in the calculations of the productivity index for both steady and pseudo steady state cases. Then the calculations were completed taking into account all conditions and factors that have a significant role in the value of the calculated productivity index.The obtained results revealed that PI increases with [well length, isotropy ratio (Kv/Kh), well thickness vs. well length] increase, while it was decreased with [ drainage area] increase in the case of steady state conditions. Also, the PI increase with length increase in the case of Pseudo steady state condition for all the studied methods, and both of Kuchuck and Economides methods seem to be close in obtained results, but Economides is the closest one to the reality and importance in application with the present case. Completion configuration has an effluence on the PI, and it is increasing with the increase of well opening to the production for such well length.Also, all the results indicated that the use of this type of technology in the field development is good and promising, and gave valuable, excellent, and optimistic results for the future production of the field in a profitable manner.
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Hao, Weijun, Zhihong Kang, and Dehua Wu. "Determination of Gas Well Productivity by Logging Parameters." Earth Science Research 6, no. 2 (April 25, 2017): 56. http://dx.doi.org/10.5539/esr.v6n2p56.
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The prediction and evaluation of reservoir productivity is a comprehensive index of the dynamic characteristics of gas reservoirs, which can provide a reasonable basis for the design and rational distribution of gasfield development plan. Proration of gas well is an important procedure in the development process, Absolute open flow as a key indicator of rational production of gas well. It is very important to determine the absolute open flow of the gas well. The Permian in Ordos Basin is a typical tight sandstone gas reservoir. The paper analyses correlation relations between different logging parameters and absolute open flow, and get the four parameters, porosity, permeability, storage coefficient（the product of porosity and effective thickness）with better correlation relations and effective thickness with best correlation relation by combining a large amount of gas logging data and static logging data and means of linear regression analysis, Then on the basis of this, a new empirical formula for calculating the absolute open flow of gas wells is obtained by using the method of multiple linear regression. The example shows that the result of this method is reasonable and reliable and the method can provide scientific basis for the prediction of natural gas absolute open flow of tight sandstone gas reservoirs.
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Diyashev, Iskander R., and Michael J. Economides. "The Dimensionless Productivity Index as a General Approach to Well Evaluation." SPE Production & Operations 21, no. 03 (August 1, 2006): 394–401. http://dx.doi.org/10.2118/94644-pa.
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Faiq, S. A., and A. V. Sarancha. "PRIDICTION OF THE PRODUCTIVITY OF HYDRAULIC FRACTURED VERTICAL WELL WITH INFINITE CONDUCTIVITY FRACTURE." Oil and Gas Studies, no. 5 (November 1, 2017): 96–99. http://dx.doi.org/10.31660/0445-0108-2017-5-96-99.
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Hydraulic fracturing is used to significantly improve well productivity, particularly in reservoirs with low permeability. In carrying out this operation in the reservoir creates a large branched system of cracks. Increase filtration connection of the wells to remote areas. This article will present the results of numerical solution of the problem related to the definition of increasing the productivity of vertical wells after hydraulic fracturing, with infinite conductivity fracture. As a result, productivity index increases with penetration ratio distance for all aspect ratios.
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Carageorgos, Themis, Marcelle Pinto Marotti, Raphael Monteiro, and Pavel Bedrikovetsky. "Laboratory and well-history based predictions of productivity decline due to oilfield scaling—analytical modelling and field study." APPEA Journal 49, no. 1 (2009): 171. http://dx.doi.org/10.1071/aj08010.
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Sulphate scaling may develop during offshore waterflood projects where mixing of injected and formation waters causes salt precipitation. Salt deposition results in permeability decline and, consequently, in impairment of well productivity. The problem has been widely presented in the literature for the North Sea, Campos Basin and the Gulf of Mexico. Recently several oil companies have reported several field cases of oilfield scaling in Australia. In this paper, methods are summarised for forecasting productivity decline from the history of well productivity index decline, produced water composition, and also from laboratory corefloods. The methods account for chemical reactions based on exact analytical solutions of inverse and forward modelling of quasi steady state oil-water flow towards producing wells. The main result obtained from the analytical model is a measure of the decline in productivity index with time for either linear flow in the case of a coreflood or the radial flow towards well. The analytical model has been used to predict further productivity decline in scaled-up producers of the deepwater offshore field X (Campos Basin, Brazil). Laboratory corefloods were carried out for field X cores and waters, and the model coefficients were determined. The productivity losses due to barium sulphate scaling have been noticed during several years of seawater flooding. The values obtained for reaction kinetics and formation damage coefficients are similar to those obtained from corefloods.
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Hagoort, Jacques. "The Productivity of a Well Completed With a Vertical Penny-Shaped Fracture." SPE Journal 16, no. 02 (January 25, 2011): 401–10. http://dx.doi.org/10.2118/104385-pa.
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Summary In this work, we present a simple polynomial relationship for the effective well radius of a well completed with a vertical, infinite-conductivity, penny-shaped hydraulic fracture as a function of fracture diameter. It is based on an analytical solution for steady-state, single-phase flow to a circular, constant-pressure surface in an infinite porous medium. This solution is extended to a vertical, penny-shaped fracture in the center of a plane circular reservoir. The effective well radius increases with increasing fracture diameter to approximately 0.2 times the fracture diameter for a fracture diameter equal to the reservoir thickness. As a rule of thumb, the productivity of a well with an infinite-conductivity, penny-shaped fracture exceeds the openhole productivity for fracture diameters larger than one-third of the reservoir thickness. The productivity of a well with a fracture diameter equal to the reservoir thickness is approximately twice the openhole productivity. The adverse effect of fracture conductivity can be estimated by a simple formula that relates fracture efficiency to the productivity index of a well with an infinite-conductivity fracture and to the ratio of the flow capacity of the fracture to that of the reservoir.
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Simões, Maurício dos Santos, Jansle Vieira Rocha, and Rubens Augusto Camargo Lamparelli. "Growth indices ans productivity in sugarcane." Scientia Agricola 62, no. 1 (January 2005): 23–30. http://dx.doi.org/10.1590/s0103-90162005000100005.
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A knowledge about the temporal development of agronomic variables in sugarcane is a very important aspect for the development of crop yield prediction models using remote sensing, and further studies are still needed. This paper describes the temporal evolution of sugarcane biophysical parameters, such as total biomass, leaf area index, number of plants per meter, and productivity. During two seasons, a commercial field in Araras/SP, planted with variety SP80-1842, on the 4th and 5th cuts, was monitored on eight different dates, and data were obtained for 2 m of sugarcane in three crop rows at 18 sampling points. Linear and multiple regression analyses were used to study growth analysis and to correlate agronomic variables (leaf area index and number of plants per meter) with biomass and productivity. Gompertz model, a sigmoidal curve, was the best adjustment curve for total biomass and yield in relation to days after cutting (r² = 0.8987 and r² = 0.9682, respectively); number of plants and leaf area index showed best fit with a cubic exponential model and a quadratic exponential model, respectively. Total biomass and cane productivity were well correlated with LAI in the first two stages of the sugarcane cycle using linear regression. At the end of the cycle, total biomass and cane productivity were more related to number of plants, and lower r² values than in other stages were obtained by the models.
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Zhao, Lun, Zifei Fan, Mingxian Wang, Guoqiang Xing, Wenqi Zhao, Chengqian Tan, and Youyou Cheng. "Productivity Evaluation of Vertical Wells Incorporating Fracture Closure and Reservoir Pressure Drop in Fractured Reservoirs." Mathematical Problems in Engineering 2020 (January 31, 2020): 1–11. http://dx.doi.org/10.1155/2020/9356178.
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In most oilfields, many wells produce in pseudo-steady-state period for a long time. Because of large reservoir pressure drop in this period, fractured reservoirs always show strong stress sensitivity and fracture closure is likely to occur near wellbores. The primary goal of this study is to evaluate productivity of vertical wells incorporating fracture closure and reservoir pressure drop. Firstly, a new composite model was developed to deal with stress sensitivity and fracture closure existed in fractured reservoirs. Secondly, considering reservoir saturation condition, new pseudo-steady productivity equations for vertical wells were derived by using the proposed composite system. Thirdly, related inflow performance characteristics and influence of some factors on them were also discussed in detail. Results show that fracture closure has a great effect on vertical well inflow performance and fracture closure radius is negatively correlated with well productivity. In this composite model, the effects of stress sensitivity of the inner and outer zone on well productivity are rather different. The inner zone’s stress sensitivity affects well productivity significantly, but the outer zone’s stress sensitivity just has a weak effect on the productivity. Strong stress sensitivity in the inner zone leads to low well productivity, and both inflow performance and productivity index curves bend closer to the bottom-hole pressure axis with stress sensitivity intensifying. Meanwhile, both maximum productivity and optimal bottom-hole pressure can be achieved from inflow performance curves. In addition, reservoir pressure is positively correlated with vertical well productivity. These new productivity equations and inflow performance curves can directly provide quantitative reference for optimizing production system in fractured reservoirs.
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AULISA, EUGENIO, AKIF IBRAGIMOV, PETER VALKO, and JAY WALTON. "MATHEMATICAL FRAMEWORK OF THE WELL PRODUCTIVITY INDEX FOR FAST FORCHHEIMER (NON-DARCY) FLOWS IN POROUS MEDIA." Mathematical Models and Methods in Applied Sciences 19, no. 08 (August 2009): 1241–75. http://dx.doi.org/10.1142/s0218202509003772.
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Motivated by the reservoir engineering concept of the well Productivity Index, we introduced and analyzed a functional, denoted as "diffusive capacity", for the solution of the initial-boundary value problem (IBVP) for a linear parabolic equation.21This IBVP described laminar (linear) Darcy flow in porous media; the considered boundary conditions corresponded to different regimes of the well production. The diffusive capacities were then computed as steady state invariants of the solutions to the corresponding time-dependent boundary value problem.Here similar features for fast or turbulent nonlinear flows subjected to the Forchheimer equations are analyzed. It is shown that under some hydrodynamic and thermodynamic constraints, there exists a so-called pseudo steady state regime for the Forchheimer flows in porous media. In other words, under some assumptions there exists a steady state invariant over a certain class of solutions to the transient IBVP modeling the Forchheimer flow for slightly compressible fluid. This invariant is the diffusive capacity, which serves as the mathematical representation of the so-called well Productivity Index. The obtained results enable computation of the well Productivity Index by resolving a single steady state boundary value problem for a second-order quasilinear elliptic equation. Analytical and numerical studies highlight some new relations for the well Productivity Index in linear and nonlinear cases. The obtained analytical formulas can be potentially used for the numerical well block model as an analog of Piecemann.
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Astafiev, V. I., and P. V. Roters. "MODELING OF DOUBLY PERIODIC SYSTEM OF PRODUCING WELLS. 2. PRODUCTIVITY INDEX." Vestnik of Samara University. Natural Science Series 17, no. 8 (June 14, 2017): 118–27. http://dx.doi.org/10.18287/2541-7525-2011-17-8-118-127.
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The question of productivity of doubly periodic systems of production wells is considered. Using the idealized production regime with a constant flow rate the analytical representation for the productivity index (PI) of the well was obtained and values depending on the drainage shapes were analyzed. Also an analytic representation for the Dietz's shape factor, which agrees with numerical calculations by the method of imaginary producing wells was obtained.
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Vaziri, Hans H., Elise M. Lemoine, and Y. Xiao. "Quantification of sand production induced improvement in productivity index." Canadian Geotechnical Journal 39, no. 5 (October 1, 2002): 1088–102. http://dx.doi.org/10.1139/t02-050.
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Centrifuge physical model tests were performed to study the mode of failure during sand production and its concomitant impact on the productivity index. The tests simulated seepage-induced failure around a multiperforated vertical well. Results indicate that in the presence of a competent cap rock (1) sand production results in the formation of a truncated cone-shaped enlarged cavity; (2) surface subsidence of the reservoir due to loss of sand mass may result in the opening of flow channels under the cap rock; (3) for a given applied head difference, sand production ceases once the enlarged cavity reduces the pressure gradient to subcritical levels; (4) the flow becomes diverted towards the upper perforations where the cavity radius is largest; and (5) the flow rate increase varies between 5 and 10 times depending on whether the mode and volume of sanding is sufficient to result in the formation of flow channels. The study performed shows that (1) the location of perforations affects the mode and magnitude of sand production; and (2) long-term productivity can be improved through managed sand production. The presence of a competent cap rock is the key to achieving substantial increases (an order of magnitude) in productivity via sanding.Key words: centrifuge test, sand production, well-bore completion, subsidence, oil sand, flow improvement.
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Zhao, Chong, Yong Zhou, Xigui Li, Pengnan Xiao, and Jinhui Jiang. "Assessment of Cultivated Land Productivity and Its Spatial Differentiation in Dongting Lake Region: A Case Study of Yuanjiang City, Hunan Province." Sustainability 10, no. 10 (October 10, 2018): 3616. http://dx.doi.org/10.3390/su10103616.
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Cultivated land is an important carrier of grain production, and scientific assessing of cultivated land productivity is of great significance to ensure food security. This paper assessed the overall productivity of cultivated land in Yuanjiang city from the perspectives of quantitative structure, spatial distribution and correlation with national land use. We applied statistical and GIS (geographic information system) spatial analysis methods to 16 secondary indicators of productivity. The results showed that the productivity index of cultivated land ranged from 1642.79 to 4140.09, concentrated in classes 2–6, among the most productive of 15 classes in total. The cultivated productivity indexes of most towns showed quantitative structural patterns of “inverted pyramid” and “dumbbell” types. Cultivated lands with high productivity showed a spatial distribution that decreased from the north to the south and increased from the center to the periphery. The spatial distribution of the higher-level classes in the cultivated land productivity index and the national cultivated land use index was similar. The correlation coefficient between the indexes for cultivated land productivity and the annual standard crop yield was 0.8817, implying that the index reflected local grain production capacity very well. In general, the research offered a reference and technical support for the sustainable use of cultivated land resources and enhanced regional cultivated land production capacity.
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Aulisa, Eugenio, Lidia Bloshanskaya, and Akif Ibragimov. "Long-term dynamics for well productivity index for nonlinear flows in porous media." Journal of Mathematical Physics 52, no. 2 (February 2011): 023506. http://dx.doi.org/10.1063/1.3536463.
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Johansen, Thormod E., Donald G. Hender, and Lesley A. James. "Productivity Index for Arbitrary Well Trajectories in Laterally Isotropic, Spatially Anisotropic Porous Media." SPE Journal 22, no. 02 (December 8, 2016): 699–711. http://dx.doi.org/10.2118/184408-pa.
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Summary For an anisotropic medium, the permeability is a second-order tensor. As such, permeability is an entity that is dependent upon the coordinate system used to describe the flow quantitatively, although the flow itself is independent of this system. In particular, this means that when a well is producing fluids from a porous medium, the coordinate system must be specified for descriptive purposes and, consequently, the permeability tensor relative to that coordinate system is determined. It is impossible to simultaneously align a 3D orthonormal coordinate system and a cylindrical well segment defined by a single axis except for special cases. Because the permeability tensor will introduce different formulations depending on the defined coordinate system, its complexity will vary accordingly. The objective of this paper is to define an optimal coordinate system with respect to the simplicity of the flow description into the well with an arbitrary trajectory for the special situation of a laterally isotropic, spatially anisotropic medium. The derivation for this optimization strategy is dependent on a sequence of flow-rate-preserving geometric transformations. The resulting virtual medium has isotropic attributes in the transformed 2D plane. Under this transform, known closed-form models are applicable by use of a single permeability value.
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Jahediesfanjani, Hossein, and Faruk Civan. "Damage Tolerance of Well-Completion and Stimulation Techniques in Coalbed Methane Reservoirs." Journal of Energy Resources Technology 127, no. 3 (January 19, 2005): 248–56. http://dx.doi.org/10.1115/1.1875554.
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Coalbed methane (CBM) reservoirs are characterized as naturally fractured, dual porosity, low permeability, and water saturated gas reservoirs. Initially, the gas, water, and coal are at thermodynamic equilibrium under prevailing reservoir conditions. Dewatering is essential to promote gas production. This can be accomplished by suitable completion and stimulation techniques. This paper investigates the efficiency and performance of the openhole cavity, hydraulic fractures, frack and packs, and horizontal wells as potential completion methods which may reduce formation damage and increase the productivity in coalbed methane reservoirs. Considering the dual porosity nature of CBM reservoirs, numerical simulations have been carried out to determine the formation damage tolerance of each completion and stimulation approach. A new comparison parameter, named as the normalized productivity index Jnp(t) is defined as the ratio of the productivity index of a stimulated well to that of a nondamaged vertical well as a function of time. Typical scenarios have been considered to evaluate the CBM properties, including reservoir heterogeneity, anisotropy, and formation damage, for their effects on Jnp(t) over the production time. The results for each stimulation technique show that the value of Jnp(t) declines over the time of production with a rate which depends upon the applied technique and the prevailing reservoir conditions. The results also show that horizontal wells have the best performance if drilled orthogonal to the butt cleats. Long horizontal fractures improve reservoir productivity more than short vertical ones. Open-hole cavity completions outperform vertical fractures if the fracture conductivity is reduced by any damage process. When vertical permeability is much lower than horizontal permeability, production of vertical wells will improve while productivity of horizontal wells will decrease. Finally, pressure distribution of the reservoir under each scenario is strongly dependent upon the reservoir characteristics, including the hydraulic diffusivity of methane, and the porosity and permeability distributions in the reservoir.
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Evers, Kerry E., Patricia H. Castle, James O. Prochaska, and Janice M. Prochaska. "Examining Relationships between Multiple Health Risk Behaviors, Well-Being, and Productivity." Psychological Reports 114, no. 3 (June 2014): 843–53. http://dx.doi.org/10.2466/13.01.pr0.114k25w4.
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Traditionally, the concept of health promotion has emphasized the reduction of health risk behaviors to reduce disease and impairment. Well-being research expands this focus to include positive constructs such as thriving, productivity, life-evaluation, and emotional and physical health. The objective of the present study was to examine the relationships between health risk behaviors and specific measures of individual well-being. Participants ( N = 790) from 49 states completed a one-time online assessment that included the Life-Evaluation Index, Emotional and Physical Health Ladders, the Health Risk Intervention Assessment, and the Work Productivity and Activity Improvement Questionnaire for General Health. Life Evaluation and physical and emotional health were all inversely related to the number of health risk behaviors, with higher well-being scores associated with lower number of risk behaviors. Across the three Life Evaluation categories (Suffering, Struggling, and Thriving) the number of health risk behaviors decreased, productivity loss decreased, and emotional and physical health increased. The results add to previous research on how reducing multiple health risk behaviors can be combined with well-being, i.e., an emphasis on increasing life-evaluation, emotional and physical health, better functioning, and productivity.
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Hagoort, Jacques. "Stabilized Productivity of a Hydraulically Fractured Well Producing at Constant Pressure." SPE Journal 11, no. 01 (March 1, 2006): 120–31. http://dx.doi.org/10.2118/88960-pa.
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Summary This paper describes a simple and easy-to-construct numerical model for the calculation of the stabilized productivity of a hydraulically fractured well producing at a constant well pressure. The model takes into account both Darcy and non-Darcy pressure losses in the fracture. Dimensionless charts are presented that illustrate productivity improvement as a function of fracture length, fracture conductivity, and non-Darcy flow. For dimensionless fracture lengths in excess of 0.2, constant-pressure productivities are significantly lower than constant-rate productivities as predicted, for example, by the McGuire-Sikora productivity improvement chart. The maximum difference is 20% for an infinite-conductivity fracture with a length of unity. Both fracture conductivity and non-Darcy flow adversely affect well productivity; the reduction in productivity is larger for longer fractures. Introduction The productivity of a well is commonly expressed by a productivity index defined as the ratio of production rate and difference between average reservoir pressure and well pressure. Stabilized productivity refers to production from a well in the semisteady-state flow regime (i.e., the regime beyond the initial transient regime), during which flow in the reservoir is dominated by the reservoir boundaries. In the past, most studies on the stabilized productivity of hydraulically fractured wells were about steady-state production or semisteady-state production at a constant rate. As we shall demonstrate in this paper, the type of well boundary condition has a significant effect on productivity, especially for long fractures. For production by pressure depletion, characterized by declining production rates, constant well pressure is a more appropriate boundary condition. In the late 1950s, McGuire and Sikora (1960) presented a productivity improvement chart for fully penetrating fractured wells producing at a constant rate under semisteady-state flow conditions based on electrical analog model experiments. The chart shows production improvement vs. fracture conductivity for various fracture lengths. The McGuire-Sikora chart is a classic in the fracturing literature and is being used to this day. In the early 1960s, Prats (1961) presented a theoretical study on the productivity of a fully penetrating fractured well under steady-state flow conditions. He showed that the effect of a fracture can be represented by an apparent or effective wellbore radius, which depends on fracture length and fracture conductivity. For fractures that are relatively small and have an infinite conductivity, the effective wellbore radius is equal to half the fracture half-length. In a follow-up study, Prats et al. (1962) demonstrated that this result also holds for stabilized flow of a slightly compressible liquid. In the mid-1970s, Holditch presented a production improvement chart (included in Lee 1989) based on experiments with a numerical reservoir simulator, which essentially confirmed the earlier results of McGuire and Sikora. Although based on production at constant rate, the McGuire-Sikora and Holditch charts are also being used for production at declining production rates (Lee 1989).
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Góral, Justyna, and Włodzimierz Rembisz. "Produkcja w rolnictwie w kontekście ochrony środowiska." Roczniki Naukowe Ekonomii Rolnictwa i Rozwoju Obszarów Wiejskich 104, no. 1 (May 17, 2017): 7–21. http://dx.doi.org/10.22630/rnr.2017.104.1.1.
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The main goal of this work was to show the necessity of implementing enviromental aspects into existing agricultural productivity theories. The authors presented the issues of integral productivity and balanced intensification. A new approach to existing measures of farm productivity was discussed as well. Productivity index including environmental aspects (so called Environmentally Adjusted Total Factor Productivity) was showed. European farming, formed by the Common Agricultural Policy, currently implements the ideas of intensification and balanced progress most effectively. At the same time, it is on the development path enabling convergence of these two ideas.
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Van der Westhuizen, Gerhardus. "Bank Productivity And Sources Of Efficiency Change: A Case Of The Four Largest Banks In South Africa." International Business & Economics Research Journal (IBER) 12, no. 2 (January 31, 2013): 127. http://dx.doi.org/10.19030/iber.v12i2.7625.
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The Malmquist productivity index was utilised to estimate the total factor productivity and productivity change of the four largest banks in South Africa for the period 1994 to 2010. Total factor productivity change can be decomposed into efficiency change and technological change, which allow for determining the sources of total factor productivity change. Various changes in the South African banking scene impacted on the average productivity of the banks. The four banks experienced, on average, regress in total factor productivity as well as regress in technological change, the latter indicating a lack of innovation. The four banks operated, on average, in the proximity of fully technical efficiency. For various reasons, South Africa still has a large unbanked community.
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You, Zhenjiang, Alexander Badalyan, Pavel Bedrikovetsky, Martin Hand, and Chris Matthews. "Productivity decline in a Salamander geothermal well: experiment, modelling and case study." APPEA Journal 54, no. 1 (2014): 345. http://dx.doi.org/10.1071/aj13035.
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Substantial formation damage and productivity decline have been observed in numerous geothermal fields. Comprehensive analysis of formation damage and prediction of productivity specifically for geothermal reservoirs, however, are not available in the literature. On the basis of laboratory study and mathematical modelling, the present work is focused on the analysis of formation damage mechanism to diagnose and predict the productivity decline. A case study of a typical Australian geothermal reservoir (Salamander field) is performed. In this case, fines migration is recognised as the most likely candidate of all formation damage mechanisms. The attaching electrostatic forces are weak at high temperatures if compared with drag and lifting forces, which detach the particles from rock surfaces. Mobilisation of lifted fines results in particle straining in thin pore throats preferentially near the well, causing severe permeability and well productivity decline. A new model based on laboratory study is developed and field production data are successfully treated by the model. The potential for fines migration and induced formation damage in geothermal wells is significantly higher than that for conventional oil and gas wells due to the weakening of attaching electrostatic forces under high temperatures. The evaluated well index from field data is in good agreement with mathematical modelling prediction. The proposed model allows for long-term productivity prediction from a short production period, which allows recommending methods of skin prevention, mitigation and removal. The model is also applicable to shale, CBM, and tight oil and gas reservoirs.
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Keshavarz, Alireza, Kate Mobbs, Aditya Khanna, and Pavel Bedrikovetsky. "Stress-based mathematical model for graded proppant injection in coal bed methane reservoirs." APPEA Journal 53, no. 1 (2013): 337. http://dx.doi.org/10.1071/aj12028.
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A technology called graded proppant (propping agent) injection that consists of the injection of proppant particles, with increasing sizes and decreasing concentrations, into a naturally fractured reservoir results in deeper percolation of the particles into the natural fracture system, and thus expansion of the stimulated reservoir area. The placement of graded proppant particles keeps the fractures open, even after pressure decline due to production. There is, therefore, an enhancement in the well productivity. This proposed technology could be used to improve the productivity of CSG wells and other unconventional resources; for example, in shales, tight gas, and geothermal reservoirs. In this peer-reviewed paper, a mathematical model for well injectivity/productivity was developed for graded particle injection in a vertical well, lying at the centre of a circular drainage area. The model is based on an analytical solution of the quasi 1D problem of coupled axisymmetric fluid flow and geomechanics. Explicit analytical equations were derived for stress, and pressure and permeability distributions, as well as for the well index during injection and production. Results of previous computational fluid dynamic studies were used to determine the hydraulic resistance resulting from proppant plugging in the fractured system. An optimal stimulation radius was identified, which resulted in the highest increment in the productivity index due to the application of graded proppant injection technology. The model was subsequently used for a sensitivity analysis using field data. The results showed that the productivity index increased more than four times by the application of this technology.
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Zhang, Yuan, Xiaoming Feng, Bojie Fu, Yongzhe Chen, and Xiaofeng Wang. "Satellite-Observed Global Terrestrial Vegetation Production in Response to Water Availability." Remote Sensing 13, no. 7 (March 28, 2021): 1289. http://dx.doi.org/10.3390/rs13071289.
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Water stress is one of the primary environmental factors that limits terrestrial ecosystems’ productivity. Hense, the way to quantify gobal vegetation productivity’s vulnerability under water stress and reveal its seasonal dynamics in response to drought is of great significance in mitigating and adapting to global changes. Here, we estimated monthly gross primary productivity (GPP) first based on light-use efficiency (LUE) models for 1982–2015. GPP’s response time to water availability can be determined by correlating the monthly GPP series with the multiple timescale Standardized Precipitation Evapotranspiration Index (SPEI). Thereafter, we developed an optimal bivariate probabilistic model to derive the vegetation productivity loss probabilities under different drought scenarios using the copula method. The results showed that LUE models have a good fit and estimate GPP well (R2 exceeded 0.7). GPP is expected to decrease in 71.91% of the global land vegetation area because of increases in radiation and temperature and decreases in soil moisture during drought periods. Largely, we found that vegetation productivity and water availability are correlated positively globally. The vegetation productivity in arid and semiarid areas depends considerably upon water availability compared to that in humid and semi-humid areas. Weak drought resistance often characterizes the land cover types that water availability influences more. In addition, under the scenario of the same level of GPP damage with different drought degrees, as droughts increase in severity, GPP loss probabilities increase as well. Further, under the same drought severity with different levels of GPP damage, drought’s effect on GPP loss probabilities weaken gradually as the GPP damage level increaes. Similar patterns were observed in different seasons. Our results showed that arid and semiarid areas have higher conditional probabilities of vegetation productivity losses under different drought scenarios.
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Abdi, Nishtman, Reza Darvishzadeh, and Hatami Maleki. "Effective selection criteria for screening drought tolerant recombinant inbred lines of sunflower." Genetika 45, no. 1 (2013): 153–66. http://dx.doi.org/10.2298/gensr1301153a.
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In this study, seventy two sunflower recombinant inbred lines were tested for their yielding ability under both water-stressed and well-watered states. The inbred lines were evaluated in a rectangular 8?9 lattice design with two replications in both well-watered and water-stressed conditions, separately. Eight drought tolerance indices including stability tolerance index (STI), mean productivity (MP), geometric mean productivity (GMP), harmonic mean (HM), stress susceptibility index (SSI), tolerance index (TOL), yield index (YI) and yield stability index (YSI) were calculated based on grain yield for every genotype. Results showed the highest values of mean productivity (MP) index, geometric mean productivity (GMP), yield index (YI), harmonic mean (HM) and stress tolerance index (STI) indices for ?C134a? inbred line and least values of stress susceptibility index (SSI) and tolerance (TOL) for C61 inbred line. According to correlation of indices with yield performance under both drought stress and non-stress states and principle component analysis, indices including HM, MP, GMP and STI could properly distinguish drought tolerant sunflower inbred lines with high yield performance under both states. Cluster analysis of inbred lines using Ys, Yp and eight indices, categorized them into four groups including 19, 6, 26 and 19 inbred lines.
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Dmour, H. N. "Productivity Index Enhancement of Stimulated Gas Wells through Hydraulic Fracturing." Petroleum Science and Technology 31, no. 3 (February 15, 2013): 225–36. http://dx.doi.org/10.1080/10916466.2010.518186.
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Kuzenko, M. V. "Some aspects of winter wheat productivity." New Technologies 17, no. 3 (August 7, 2021): 71–76. http://dx.doi.org/10.47370/2072-0920-2021-17-2-71-76.
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The article presents studies carried out in 2018–2019 and 2019–2020 in the southern foothill zone of the North-West Caucasus in the fields of the selection and primary seed produc- tion department of the Adygh Research Institute of Agriculture. The aim was to study the actual, biological or potential yield of winter soft wheat varieties cultivated in the region, as well as the ratio of the mass of the grain part and the harvested straw - the yield index. The studied varieties were divided into groups according to plant height: semi-dwarfs (up to 90 cm), short-stemmed (up to 105 cm), medium-sized (up to 120 cm). According to the results of the studies carried out, differences in the studied characteristics were revealed. In the group of semi-dwarf varieties, the grain yield varied from 7,25 to 8,05 t/ha, short-stemmed 7,78–8,91 t/ha, medium-sized 7,34–9,60 t/ha. The highest grain yield was shown by the Vekha variety (9,60 t/ha) belonging to the group of medium-sized varieties, from the short-stemmed Maikopchanka varieties (8,91 t/ha) stood out, Kalym semi-dwarf varieties (8,05 t/ha). The biological yield in the experiment varied from 9,37 to 15,29 t/ha. From semi-dwarf varieties, Grom stood out (14,06 t/ha), short-stemmed varieties – Mafe (10,8 t/ha), medium-sized varieties – Vekha (15,29 t/ha). The difference between the actual and biological grain yield of varieties belonging to the short-stem group was the smallest in comparison with the varieties of the semi-dwarf and medium-grown group. On average, over two years of research, the harvesting index was 46,9–53,2%. Semi-dwarf winter wheat varieties had the maximum value of this indicator. In the group of short-stemmed Grom and Graf varieties, the ratio of the mass of the grain part to the harvested straw varied from 46,8% (Velena) to 50,5% (Alekseich). The harvesting index for medium-sized varieties was at the level of 46,9–51,8%. The Vekha variety, which showed the maximum value, stood out from this group.
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Malinouskaya, Iryna, Christophe Preux, Nicolas Guy, and Gisèle Etienne. "Impact of geomechanical effects during SAGD process in a meander belt." Oil & Gas Sciences and Technology – Revue d’IFP Energies nouvelles 73 (2018): 17. http://dx.doi.org/10.2516/ogst/2018011.
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In the reservoir simulations, the geomechanical effects are usually taken into account to describe the porosity and the permeability variations. In this paper, we present a new method, patented by authors, which allows to model the geomechanical effects also on the well productivity index. The Steam Assisted Gravity Drainage (SAGD) method is widely used for the heavy oil production. A very high variation in pressure and temperature play a significant role on the petrophysical properties and may impact the productivity estimation. In this paper we develop a new simplified geomechanical model in order to account for the thermal and pressure effects on the porosity, permeability and the productivity index during the reservoir simulation. At the current state, these dependencies are defined using semi-analytical relationships. The model is applied to a meandering fluvial reservoir based on 3D outcrop observations. The productivity is found underestimated if the pressure and temperature effects on the petrophysical properties are ignored in the reservoir simulation. Moreover, this study shows an important impact of thermal effects on the productivity estimation. The results of this work show that it is essential to properly take into account the geomechanical effects on the petrophysical properties and also on the productivity index for a better productivity estimation.
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Vashchenko, O. V. "PIG PRODUCTIVITY UNDER PURE BREEDING AND CROSSBREEDING." Animal Breeding and Genetics 51 (March 28, 2018): 34–41. http://dx.doi.org/10.31073/abg.51.05.
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For the research the groups were formed by method of analogues based on origin, age, physiological state, live weight. Studying sperm productivity, the number of ejaculates obtained during the year, average volume, concentration, and the total number of spermatozoa in the ejaculate were taken into account and conducted according to conventional techniques using a digital photometer “SDM-30” produced by "Minitüb”. Indicators of economical useful traits of the test animals were calculated according to primary zoo-technical accounting by standard methods of biometric analysis. To determine breeding value of animals by the BLUP method, software developed at the Institute of Pig Breeding "System determining the breeding value of pigs" was used. In carrying out the work, population genetics and mathematical methods were applied for studying of patterns of variability, repeatability, assessment of the genotype of animals.
Reproductive quality of the sows was assessed by multiparity (total number of piglets at farrowing), prolificacy (piglet’s weight at birth, kg), milk ability (total weight of litter at 21 days, kg) piglet’s weight at weaning and survival of offspring to weaning. Survival of piglets, homogeneity and uniformity of litter were determined by modified M. D. Berezovsky – D. V. Lomako index and V. P. Kovalenko homogeneity index. Growth and development were controlled by change of individual live weight via weighing. Average daily gain was determined based on the initial and final live weight and number of days between weightings.
Dynamics of indicators of growth and development, maternal qualities of sows and sperm productivity and fertility of boars at the purebred animal of initial breeds and live weight and age at 100 kg in the hybrids of first generation were studied. The youngsters obtained at crossbreeding Large White breed of domestic and foreign selection with Landrace had the best indicators of growth and development than the purebred counterparts in all age periods. Higher live weight at weaning at age of 60 days was typical for combination ♀LWE x ♂LE and ♀LE x ♂LWE; it is quite natural, because they had lower average number of piglets at weaning. For maturing volumes of back of the carcass and a well-developed layer of fat should be adjusted to Landrace sows and Large White boars. Fattening of commercial hybrids obtained by this scheme under Ukrainian conditions is advisable to check out at animal’s live weight of 115 ... 120 kg.
Significant correlations were proven on the basis of: BLUP index – back fat thickness at the level of the 6-7 thoracic vertebra – -0,221 ± 0,0938 (tr = 2,35), BLUP index – back fat thickness on sacrum – -0,298 ± 0,0898 (tr = 3,31), BLUP index – back fat thickness at the midpoint of the back between the withers and sacrum – -0,239 ± 0,0929 (tr = 2,57), BLUP index – body length – -0,338 ± 0,0873 (tr = 3, 86), BLUP index – multiparity – -0,294 ± 0,0900 (tr = 3,26), BLUP index – total weight of the litter at the date of weaning – -0,233 ± 0,0932 (tr = 2,49). Keeping the selection process towards selection and combination of parental pairs by BLUP method is one of the ways to increase the productive capacity of the animals.
According to the research it was found that asymmetry of testes sizes was observed together with individual peculiarities of testes form at the same breeding boars. Testes have physiological asymmetry. Ratio of areas of the left testes to right was Sl/Sr = 1.04, and volumes respectively Vl/Vr = 1.20, on average, left testes by their areas were 2.7% more than the right, and by volumes – 14.6% respectively.
Comparing the live weight of boars with weight of their testes does not have a logical pattern. The average weight of testes was 0.14% of the live weight of breeding boars. Total volume of ejaculate on a group of boars was 355,3 ± 16,9 ml. The concentration of sperm in the ejaculate was 64,2 ± 4,6 billion, activity – 8,7 ± 0,2 points. The studies found that boars with greater weight of testes produce sperm with more sperm concentration and that's why more sperms in the ejaculate were obtained from them.
Combination of Landrace and Large White breeds is apposite for obtaining precocious pigs with well-developed layer of fat at the 6-7 thoracic vertebra and high level of prolificacy (1,8-1,9 kg).
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Medeiros, F., B. Kurtoglu, E. Ozkan, and H. Kazemi. "Analysis of Production Data From Hydraulically Fractured Horizontal Wells in Shale Reservoirs." SPE Reservoir Evaluation & Engineering 13, no. 03 (June 7, 2010): 559–68. http://dx.doi.org/10.2118/110848-pa.
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Summary This paper discusses the analysis of production data from hydraulically fractured horizontal wells in shale reservoirs. The stimulated volume around the well is simulated by a naturally fractured region. A semianalytical model incorporating the key features of reservoir heterogeneity and the details of hydraulic fracture and wellbore flow is used to present production-decline characteristics in terms of transient-productivity index. Production-decline analysis of fractured horizontal wells in shale-oil and shale-gas formations by transient-productivity index is explained and demonstrated by field applications.
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Suparto, Suparto. "APPLIED PRODUCTIVITY MEASUREMENT WITH OBJECTIVE MATRIX (OMAX) METHOD (Case Study: Service Department in PT. Astra International Tbk Auto 2000 - Kenjeran Branch)." Tibuana 2, no. 02 (July 31, 2019): 26–30. http://dx.doi.org/10.36456/tibuana.2.02.1926.26-30.
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Astra International Tbk. Auto 2000 branch Kenjeran is a company department in sales, service and spare parts services. To evaluate the productivity in the service department for this time, it is necessary to measure productivity properly and correctly because productivity measures can be used as material for consideration in carrying out an upcoming productivity planning. This research was conducted in January-December 2013. The productivity method used is the Objective Matrix (OMAX) method. From the results of productivity measurements, it is known that the best productivity occurs in July, which is equal to 768.8, well above the standard value of 300. The worst productivity occurred in February, which amounted to equal 174,8. From the achievement of the score it can be seen that the criteria that do not contribute to the productivity index are criteria 1, namely the comparison between unit handling and the use of working hours because it has the smallest score to equal 47. The strategy for increasing productivity is to evaluate the causes of decreasing productivity in the lowest criteria.
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Ibragimov, Akif, Dinara Khalmanova, Peter P. Valko, and Jay R. Walton. "On a Mathematical Model of the Productivity Index of a Well from Reservoir Engineering." SIAM Journal on Applied Mathematics 65, no. 6 (January 2005): 1952–80. http://dx.doi.org/10.1137/040607654.
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Fayyaz, K., M. Hekmatzadeh, and S. Gerami. "EFFECT OF DISCRETIZATION ON CALCULATION OF SLANT WELL PRODUCTIVITY INDEX IN NUMERICAL RESERVOIR SIMULATION." Brazilian Journal of Petroleum and Gas 11, no. 3 (October 16, 2017): 141–48. http://dx.doi.org/10.5419/bjpg2017-0012.
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Berhe, Alem Gebremedhin. "An Empirical Analysis of Productivity Changes in the Ethiopian Commercial Banks: Using DEA- Based Malmquist Productivity Index Approach." Accounting and Finance Research 10, no. 1 (February 25, 2021): 48. http://dx.doi.org/10.5430/afr.v10n1p48.
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The rationale of this paper is to measure the productivity change of commercial banks in Ethiopia based on DEA-based Malmquist productivity index approach. For this purpose, this study employed a balanced panel data of eight commercial banks operating from 2006 to 2017. The result shows that the banks under study were found to have reported a slight productivity progress of 0.4% over the whole study period. The productivity improvement is accredited to the technological progress (0.9%) rather than the efficiency loss (0.5%). Meanwhile, the finding suggests that the decline in the technical efficiency of the banks was caused both by pure technical efficiency and scale efficiency. Alternatively, the finding of the study indicates that the productivity performance of all the banks under study, with the exception of AIB and CBE, remain almost constant in spite of their size during the period. AIB and CBE have exhibit an average productivity progress of 2% and 1.4% respectively during the study period. In the study period, AIB was found to be the most inefficient (2.4%) and the most productive one (2%) comparing to other banks in the study due to retrogress in scale efficiency change (2.1%) as well as technical progress (4.5%) in that order. Further, the paper suggests that the productivity performance of the banks under study was not significantly different in the period. So, the banks have to move forwards their technology to increase productivity more and more, while improving the resource utilization efficiency by up grading their managerial practices and scale operations (optimum size)
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Sewerniak, Piotr. "Plant species richness or soil fertility: which affects more the productivity of Scots pine in Central Europe?" Annals of Forest Research 63, no. 2 (December 31, 2020): 57–73. http://dx.doi.org/10.15287/afr.2020.2003.
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It has been highlighted that forest productivity is related both to species richness and to soil fertility; however, thus far it has not been investigated which of these agents is more important for the productivity. The goal of this study was to examine this problem with regard to Scots pine (Pinus sylvestris L.) stands in Central Europe. The study was conducted in 129 plots located in SW Poland. The productivity of even-aged pine stands was estimated based on site index. Plant species richness was investigated regarding the total richness as well as the richness referring to particular forest strata (overstorey, understorey, herb layer). Soil fertility was studied regarding the nutrients’ stocks, the contents of fine-textural classes, pH, the TOC content and the values of Soil Trophic Index. The importance of the variables for the site index was examined using Spearman correlations and the stepwise regression. Productivity of the studied stands was predominantly correlated stronger to species richness than to soil properties being related to its fertility. The higher importance for the productivity of soil variables than of species richness was exclusively found for the poorest plots being represented by Podzols. This study highlights the high importance of species richness occurring in particular forest strata for the forest stand productivity, which could involve consequences for forest economy as well as for CO2 sequestration. Thus, the research delivers strong argument for the conversion of pine mono-stands occurring in Central Europe for mixed forests.
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Sorek, Nadav, Jose A. Moreno, Ryan N. Rice, Guofan Luo, and Christine Ehlig-Economides. "Productivity-Maximized Horizontal-Well Design With Multiple Acute-Angle Transverse Fractures." SPE Journal 23, no. 05 (August 17, 2018): 1539–51. http://dx.doi.org/10.2118/170965-pa.
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Summary Hydraulic fractures propagate perpendicular to the horizontal-well axis whenever the drilling direction is parallel to the minimum-principal-stress direction. However, operators frequently drill horizontal wells parallel to lease boundaries, resulting in hydraulic-fracture vertical planes slanted at angles less than 90° from the well axis. The stimulated-rock-volume (SRV) dimensions are defined by fracture height, well length, and fracture length multiplied by the sine of the angle between fracture planes and the horizontal-well axis (fracture angle). The well productivity index (PI) under boundary-dominated flow (BDF) is given by the PI for one fully penetrating fracture multiplied by the number of fractures. An extension of the unified-fracture-design (UFD) approach for rectangular drainage areas enables determination of the unique number of fractures that will maximize well productivity under BDF conditions given the formation permeability, proppant mass, fracture angle, and well spacing. Fracture length and width vary depending on the fracture angle, but the total-propped-fracture volume remains constant. Because the likely reason for drilling at an angle to the minimum-stress direction is to better cover a lease area with north/south and east/west boundaries, the smallest fracture angle will be 45°, corresponding to northwest/southeast or northeast/southwest minimum-stress direction. This results in the need to lengthen fractures by at most 40% to preserve the SRV for a given horizontal-well length and spacing. For the same sufficiently large proppant mass, this will reduce fracture conductivity by the same factor. However, because the flow area has increased, the result will be greater well productivity. This study shows a simple strategy for designing wells to maximize productivity even when not drilled in the minimum-stress direction.
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HITANI, ABDUL HAFIDZ, NURLIZA NURLIZA, and EVA DOLOROSA. "ANALISIS DAYA SAING USAHA TERNAK SAPI POTONG RAKYAT DI KABUPATEN MEMPAWAH." Jurnal Social Economic of Agriculture 6, no. 1 (September 8, 2017): 39. http://dx.doi.org/10.26418/j.sea.v6i1.21585.
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This research aims to analyze the development of profitability, productivity, and output growth as well as to analyze the development of the competitiveness of the beef cattle bussiness in Mempawah Regency. This research took placed in 9 Sub-distric in Mempawah. The method used was the descriptive method using the panel data from 2008-2013. The data were processed using the method of ICI (Industrial Competitive Index) by finding out the indicator which included the index of profitability, productivity and output growth. The results of the analysis showed that the growth rate of the profitability index was 15.07%, the productivity index 12.67% and output growth index -4.74%. Based on the result of the analysis, the growth rate of the industry competitive index (ICI) for 9 Sub-distric in Mempawah Regency overall had a positive value. This indicated that the 9 Sub-distric in Mempawah Regency had the capability of competitiveness. The growth rate of the industrial competitive index for Mempawah Regency was 9.12%.
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Mendaza, Raquel Mateo. "Matching productivity indexes and diachronic evolution: The Old English affixesful-, -isc, -cund, and-ful." Canadian Journal of Linguistics/Revue canadienne de linguistique 60, no. 1 (March 2015): 1–24. http://dx.doi.org/10.1017/s0008413100000517.
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AbstractThis article measures the productivity index of the Old English suffixes-cund, -ful,and-iscas well as the prefixful-and checks the results against the diachronic evolution of the affixes. The frameworks brought to the discussion includeType frequencymeasurement, as well as productivity indexes proposed by Baayen (1992, 1993, 2009) and Trips (2009). The sources are both textual(The Dictionary of Old English Corpus)and lexicographical (the lexical database of Old EnglishNerthus).The conclusion drawn is that Baayen's (1992, 1993, 2002) index ofGlobal Productivityprovides the most consistent results with the diachronic evolution of the affixes.
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Mubin, Ahmad, and Syaiful Zainuri. "PENINGKATAN PRODUKTIVITAS DAN KINERJA LINGKUNGAN DENGAN METODE GREEN PRODUCTIVITY DI PT. XYZ." Jurnal Teknik Industri 13, no. 2 (December 28, 2012): 126. http://dx.doi.org/10.22219/jtiumm.vol13.no2.126-132.
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Ahmad Mubin DAN Syaiful ZainuriJurusan Teknik Industri, Fakultas Teknik, Universitas Muhammadiyah MalangLaman: ahmadmbn@ymail.comABSTRAKProduktivitas merupakan hal yang sangat penting bagi perusahaan sebagai salah satu cara untuk memantau kinerjaproduksinya. Pengukuran produktivitas dilakukan untuk mengetahui tingkat kinerja perusahaan dan dapat dijadikansebagai pedoman untuk melakukan perbaikan secara terus-menerus. Demikian pula, aspek lingkungan telah menjadi isupenting dan strategis yang harus disikapi oleh industri dengan baik dan terus ditingkatkan kinerjanya. Agar perusahaanmampu meningkatkan produktivitas sekaligus menurunkan dampak lingkungan perlu digunakan pendekatan modelGreen Productivity. ��������������Tujuan penelitian ini yaitu mengidentifikasi faktor-faktor yang berpengaruh terhadap produktivitasdan kinerja lingkungan, serta memberikan usulan perbaikan menggunakan metode Green Productivity berdasarkannilai indeks Benefit-Cost Ratio (BCR) tertinggi.��������������������������������������������������������������� Hasil penelitian menunjukkan bahwa faktor-faktor yang berpengaruhterhadap produktivitas dan kinerja lingkungan adalah kinerja ketel uap (boiler) dan penanganan limbah cair. Untukmengatasi masalah tersebut, maka diperlukan suatu alternatif perbaikan. Alternatif perbaikan yang diusulkan adalahmemasang Heat Exchanger dan DAF (Dissoveled Air Floatation). Dari hasil estimasi kontribusi, alternatif yang terpilihtersebut dapat memberikan peningkatan yang signifikan yakni indeks produktivitas ketel uap sebesar 103,64% lebih baikdaripada kondisi awal dan untuk indeks produktivitas limbah minyak sebesar 104,18% lebih baik daripada kondisi awal,serta terjadi penurunan kadar CO sebesar 0,19 dan kadar minyak dan lemak sebesar 0,17.Kata kunci: Produktivitas, Kinerja Lingkungan, Green Productivity, Benefit-Cost Ratio.ABSTRACTProductivity is very important for the company as a way to monitor the production performance. Productivitymeasurement is performed to determine the level of productivity performance of the company and can be used as guidelinefor continuous improvement. Similarly, the environmental aspect has become an important and strategic issues that must beaddressed by the industry well and improved its performance continuously. In order to improve productivity while loweringenvironmental impact the company need to use Green Productivity model approach. The purposes of this research were toidentify factors that affect productivity and environmental performance, as well as providing proposed improvement usingGreen Productivity method based on the highest value of the Benefit-Cost Ratio (BCR) index. The results showed that thefactors that affect productivity and environmental performance are the boiler performance and the wastewater treatment.Therefore to overcome these problems, it was needed an improvement alternative. The improvement alternative proposedwere to install Heat Exchanger and DAF (Dissoveled Air Floatation). From the estimated contribution, the chosen alternativecould provide a significant increase in the productivity index of boiler at 103.64% better than the initial condition andproductivity index of oil waste by 104.18% better than the initial condition, also there were decreased level of CO level at0.19 and 0.17 for oil and fat.Key words: Productivity, Environmental Performance, Green Productivity, Benefit-Cost Ratio
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Yang, Wanping, Bingyu Zhao, Jinkai Zhao, and Zhengda Li. "An Empirical Study on the Impact of Foreign Strategic Investment on Banking Sustainability in China." Sustainability 11, no. 1 (January 1, 2019): 181. http://dx.doi.org/10.3390/su11010181.
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In order to improve the banking sustainability in China, China’s government has announced that the restrictions on foreign shareholding ratio in domestic banks will be canceled. However, the effectiveness of foreign strategic investment needs checking. In addition, under the new policy, the method by which banks formulate appropriate internal decisions about introducing foreign strategic investment is an important issue for bank managers. Continuous productivity growth will bring sustainable development; therefore, the aims of this paper are: (1) to find the relationship between foreign strategic investment and productivity change of China’s banks, and to verify the effectiveness of introducing foreign strategic investment; (2) to find the optimal foreign shareholding ratio; (3) to show how foreign strategic investment affects the productivity of China’s banks, i.e. the transmission mechanism between them, and to provide bank managers with evidence and support for making decisions on introduction of foreign strategic investment. This paper employs the Malmquist-Luenberger index and combines it with Epsilon-based-measure to derive a new index, i.e. the EBM-Malmquist-Luenberger index, to measure the dynamic productivity change of China’s banks. In addition, the dynamic panel data and system GMM estimator are used to analyze the transmission mechanism as well as the impact of foreign strategic investment on the productivity of China’s banks. The results revealed three facts. First, when the foreign shareholding ratio increases within a given range, foreign strategic investment continuously improves the productivity and sustainability of China’s banks. Second, an inverse N-shaped relation between foreign strategic investment and productivity growth of China’s banks is supported, and the optimal foreign shareholding ratio is 20.16%. Last but not least, foreign strategic investment improves the productivity and sustainability of China’s banks, mainly through changing scale efficiency. The results of this paper may provide support for policy formulation of China’s banks.
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Luo, Wanjing, Changfu Tang, and Yin Feng. "A Semianalytical Model for Horizontal-Well Productivity With Pressure Drop Along the Wellbore." SPE Journal 23, no. 05 (February 12, 2018): 1603–14. http://dx.doi.org/10.2118/189973-pa.
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Summary This study aims to develop a semianalytical model to calculate the productivity index (PI) of a horizontal well with pressure drop along the wellbore. It has been indicated that by introducing novel definitions of horizontal-well permeability and conductivity, the equation of fluid flow along a horizontal well with pressure drop has the same form as the one for fluid flow in a varying-conductivity fracture. Thus, the varying-conductivity-fracture model and PI model can be used to obtain the PI of a horizontal well. Results indicate that the PI of a horizontal well depends on the interaction between horizontal-well conductivity, penetration ratio, and Reynolds number. New type curves of the penetration ratios with various combinations of parameters have been presented. A complete-penetration zone and a partial-penetration zone can be identified on the type curves. Based on the type curves, two examples have also been presented to illustrate the advantages of this work in optimizing parameters of horizontal wells.