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1
Perrin, José, Didier Belaud, Jean-Pierre Yver, and Charles Naville. "S-wave anisotropy from two dipole sonic data processing methods, confronted with fracture permeability, logs and cores." Science and Technology for Energy Transition 77 (2022): 13. http://dx.doi.org/10.2516/stet/2022006.
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The present paper consists in two parts, determined by the historical emerging production of Dipole Sonic Imager (DSI) measurements and results in the early 1990’s. The DSI data were processed following two methods simultaneously developed in France and in USA by Schlumberger. In the first part the early dipole sonic S-wave velocity results obtained in late 1993 are confronted with the other borehole data obtained in the scientific borehole MM-1, entirely cored and extensively logged, as part of the comprehensive scientific project named Géologie Profonde de la France (GPF), conducted by the Bureau de Recherches Géologiques et Minières (BRGM, i.e. the French Geological Survey), in Ardèche, southern France. In 1994, José Perrin summarized and integrated all the borehole information including the preliminary results from an azimuthal “rotation scan” of S-wave sonic slowness determination method quickly developed in Schlumberger-France and aiming at detecting only the presence of S-wave velocity anisotropy in a first step. The initial results were presented to the French industrial logging community in April 1994, prior to the commercialization of any S-wave splitting computer detection routine applied to dipole sonic data. The second part focuses on the comparison of the dipole sonic S-wave anisotropy detection results from two methods produced at a later time by Schlumberger, namely: a) results from the commercial S-wave anisotropy detection routine based on cross energy minimization, obtained in October 1994, and b) principal S-wave azimuth results sorted from the “rotation scan” azimuthal method, produced in 1995 and further improved in July 1997. After discussing the discrepancies of the principal fast S-wave azimuth derived from the two methods with diverse specialists in Schlumberger, over several years, and on a spare time basis, the authors expose constructive explanations in the present paper. A limited overview of the latest dipole sonic data processing developments has also been attempted to better understand the differing S-wave birefringence results obtained in MM-1, suggesting that the rock formation in the immediate borehole vicinity, up to three times the borehole radius, may not be homogeneous along the borehole depth depending on the local geological context. Besides, the Fast Azimuth split S-wave (FAZ) fits with the strike of major regional faults and parallel to the maximal horizontal palaeo-stress, which happens to be nearly orthogonal to the local present stress direction accepted by the geologists! The present case study suggests that the S-wave anisotropy results ought to become more reliable, mainly on the accuracy and precision of the FAZ. Additionally, the efficiency of the semblance parameter for S-wave attenuation anisotropy detection is pondered, where no S-wave velocity anisotropy is detected over the dipole sonic receiver array.
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Asmoro, Cahyo Puji, and Hana Susanti. "Analysis of Do-it-Yourself (DIY) Electrode for Soil Resistivity Measurement Practical of Geology and Geophysics Subject at Earth and Outerspace Laboratory." Jurnal Temapela 3, no. 1 (November 9, 2020): 10–18. http://dx.doi.org/10.25077/temapela.3.1.10-18.2020.
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This study describes the process of designing, manufacturing and the performance of Do It Yourself (DIY) electrodes for Soil Resitivity Measurement (SRM) practicum in the Geophysical Geology course. The aim is to produce electrodes that can be used with the Geo Tester tool from the Fluke 1623. The method used was the Research and Development method. the required electrode had been analyzed prior to the idea of making make your own electrode was created. The electrodes were designed in such a way as to consider the level of accuracy, convenience, safety and economics. The results showed that the DIY electrode was made well, the limited trial of data collection using the Schlumberger and Wenner configuration methods resulted in data error values of 2.43% and 4.1%, respectively. The results were much smaller than the accepted minimum error threshold, namely 20%. The validation results from DIY electrode users (Data Collection Team) and Earth Physicist lecturers gave an average rating of 3.8 out of a scale 4. Thus, DIY eceltrodes can be used in practical for Geophysical Geology lectures in the Earth and Space Laboratory
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Alzahra, Salsa Rizkia, Didik Taryana, and Ferryati Masitoh. "Identifikasi lapisan akuifer Kawasan Dataran Suko Mulyo, Desa Suko Mulyo, Kecamatan Sepaku, Kabupaten Penajam Paser Utara, Kalimantan Timur." Jurnal Integrasi dan Harmoni Inovatif Ilmu-Ilmu Sosial (JIHI3S) 1, no. 11 (November 2, 2021): 1239–56. http://dx.doi.org/10.17977/um063v1i11p1239-1256.
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The Suko Mulyo Plain area, Sepaku, North Penajam Paser is experiencing problems with uneven groundwater availability and limited groundwater supply for clean water sources. The purpose of the study was to determine the condition of rock layers based on resistivity values and identify the presence of aquifers. The method used is a configuration geoelectric survey schlumberger 200 meters 5 location points which is then processed with IPI2Win. IPI2Win serves to visualize the modeling of the aquifer layer. Geoelectric modeling results show that the hydrostratigraphy of the Suko Mulyo Plain Area consists of claystone, limestone, sandstone, quartz sandstone and claystone with coal insertion with a resistivity range of 56.2 to 3.65 m. In addition, observation and secondary data processing resulted in geomorphological interpretations in the form of structural denudational terrace and structural ridges. These rock formations and geomorphological units affect the presence of aquifers identified in the structural valley plains of Dusun 3 and the structural hills of Dusun 1 with a thickness of 52.6 meters and 64.3 meters. The results of the study are expected to be used as a reference for determining groundwater drilling points and as a basis for consideration of government officials in determining groundwater resource management policies.
Kawasan Dataran Suko Mulyo, Sepaku, Penajam Paser Utara mengalami permasalahan ketersediaan air tanah yang tidak merata dan keterbatasan suplai air tanah untuk sumber air bersih. Tujuan penelitian untuk mengetahui kondisi lapisan batuan berdasarkan nilai resistivitas dan mengidentifikasi keberadaan akuifer. Metode yang dilakukan adalah survei geolistrik konfigurasi schlumberger lintasan 200 meter pada 5 titik lokasi yang kemudian diolah dengan IPI2Win. IPI2Win berfungsi memvisualisasikan pemodelan lapisan akuifer. Hasil Pemodelan geolistrik menunjukkan bahwa hidrostratigrafi Kawasan Dataran Suko Mulyo terdiri dari batu lempung, batu gamping, batu pasir, batu pasir kuarsa dan batu lempung dengan sisipan batubara dengan rentang resistivitas 56,2 hingga 3,65 m. Selain itu, observasi dan pengolahan data sekunder menghasilkan interpretasi geomorfologi berupa Teras Denudasional Struktural dan Satuan Struktural. Formasi batuan dan satuan geomorfologi ini berpengaruh terhadap keberadaan akuifer yang teridentifikasi pada Dataran lembah struktural Dusun 3 dan Perbukitan struktural Dusun 1 dengan ketebalan 52,6 meter dan 64,3 meter. Hasil penelitian diharapkan dapat dijadikan acuan menentukan titik pengeboran air tanah dan sebagai dasar pertimbangan perangkat pemerintahan dalam penentuan kebijakan pengelolaan sumber air tanah.
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Tonge, Piers. "Exploiting the industry skills shortage as a competitive advantage." APPEA Journal 50, no. 2 (2010): 715. http://dx.doi.org/10.1071/aj09079.
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Developing skilled petro-technical professionals (PTPs) has the greatest lead-time of any activity that oil and gas companies undertake today. Australia could double its gas production by 2020, which would create 50,000 new jobs. This will intensify competition for skilled petrotechnical professionals, and may drive up people costs. The market for PTPs in Australia is tight today, with active competition for technical talent between the oil and gas industry and other extractive industries. Conventional and unconventional oil and gas projects on Australia’s west and east coasts are already chasing the same, limited, talent pool. Competition for experienced PTPs will be intensified by the impending crew change, with a disproportionate number of experienced PTPs due to retire from Australia’s oil and gas industry over the next decade. Schlumberger Business Consulting has been benchmarking the people situation in the global oil and gas industry for the past six years, and working with exploration and production companies to address it. This paper will present our analysis of the global, and Australian, situation, with quantification of the skill balance through our demand and supply model. It will also highlight specific technical skills that will be in short supply, implications of the skills shortage, as well as potential mitigations to create competitive advantage.
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Boeije, C. S., and W. R. Rossen. "Fitting Foam-Simulation-Model Parameters to Data: I. Coinjection of Gas and Liquid." SPE Reservoir Evaluation & Engineering 18, no. 02 (May 6, 2015): 264–72. http://dx.doi.org/10.2118/174544-pa.
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Summary Cheng et al. (2000) present a simple method to fit foam-simulation parameters without oil to data for pressure gradient as a function of superficial velocities of gas and liquid. The key in this process is the identification of “high-quality” (high gas fraction) and “low-quality” foam regimes. The method is essentially the same for the foam-model parameters in foam models in STARS (Cheng et al. 2000), UTCHEM (Cheng et al. 2000), or ECLIPSE (Schlumberger 2010). Often, however, available data are more limited: pressure gradient for one scan of foam quality at fixed total superficial velocity. We show how to extend this method to the more-limited data set. The transition in regimes occurs at the foam quality with the maximum-pressure gradient. We illustrate the method by fitting parameters to several published data sets. Our approach is simple and direct. The model fit would be appropriate for an enhanced-oil-recovery process involving foam injection at finite water fraction, but not a surface-alternating-gas foam process involving large slugs of gas and liquid. For the latter process, the model fit should focus on data relevant to that process (i.e., at extremely high foam quality). The approach assumes an abrupt transition between high- and low-quality-foam regimes (e.g., a large value of epdry in the STARS foam model). If the transition is less abrupt, the parameter values quickly obtained by this method could provide the initial guess for a computer-based least-squares fit of all parameters, including a smaller value of epdry, and a check on the parameters so obtained.
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Al-Khersan, Emad. "Integrated Ground Penetrating Radar and Electrical Resistivity Study to Explore Such Basrah Low Resistivity Soils for Engineering Purposes, Southern Iraq." Iraqi Geological Journal 54, no. 2E (November 30, 2021): 104–21. http://dx.doi.org/10.46717/igj.54.2e.7ms-2021-11-23.
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A total of 45 ground penetrating radar profiles have been conducted in Basrah City, Southern Iraq, to detect buried utilities in such soils which have not been tested before. This study tries to explore how much this technique can be useful for Basrah low resistivity soils during arid and humid seasons. In Basrah University Campus (silty clay soil) and Basrah Sport City (silty sand soil), 37 and 8 ground penetrating radar profiles were achieved inside these locations respectively. Vertical electrical sounding (Schlumberger array) and electrical profiling (Wenner array) were also used in compatibility with radar surveys side by side in all sites. Here, radargrams do not reveal much more details about the subsurface conditions because of the moisture content and soil characterizations. The actual penetrating depth of 250 and 500 MHz antennas are limited to 1.4 and 0.4 m respectively due to the soil total dissolved solids of about 6790 ppm. The tests suggest that the 250 MHz antenna is somewhat better than the 500 MHz one for detecting the shapes and depths of the buried bodies in silty clay soils during rainy or even arid periods. In Basrah Sport City (500 MHz) antenna, the radargram wave signals are not good for more than 2.5 m depth, and this antenna, rather than the 250 MHZ one is suitable for silty sand soil type.
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Dlugosch, Raphael, Thomas Günther, Mike Müller-Petke, and Ugur Yaramanci. "Improved prediction of hydraulic conductivity for coarse-grained, unconsolidated material from nuclear magnetic resonance." GEOPHYSICS 78, no. 4 (July 1, 2013): EN55—EN64. http://dx.doi.org/10.1190/geo2012-0187.1.
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The prediction of hydraulic conductivity [Formula: see text] from nuclear magnetic resonance (NMR) measurements has been performed primarily in sandstones. In hydrogeological applications, however, unconsolidated material is more prevalent. Compared to sandstones, unconsolidated sediments can show pore sizes up to several millimeters. The known (semi-)empiric relations to estimate [Formula: see text] from NMR have been applied on this material, but the underlying assumptions are not valid for large pores. We formulated a new model, called the Kozeny-Godefroy model. It is based on capillary pores with a single pore radius, and accounts for bulk water relaxation and relaxation in porous media under fast- and slow-diffusion conditions. The bulk-water relaxation and slow-diffusion conditions significantly affect the NMR measurements on coarse material. If the impact of the bulk-water relaxation is well known and small, a maximum [Formula: see text] can be derived from NMR measurements by accounting for the slow-diffusion case. The model replaces the empirical factors in known relations with physical, structural, and intrinsic NMR parameters. Focusing the calibration on material-specific NMR parameters improves the prediction of [Formula: see text] for similar material. Measurements on well-sorted glass beads and natural sands with different grain sizes are used for evaluation. These measurements confirm the applicability of the new model and, for coarse material, show the limit of the fast-diffusion-based Seevers and Schlumberger-Doll-Research equations. The application of our model is limited to (1) simple pore geometries, and (2) materials with a small range of pore sizes.
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Stoll, Johannes B., and Karsten Bahr. "Optimization of signal‐to‐noise ratio in dc soundings." GEOPHYSICS 65, no. 5 (September 2000): 1495–500. http://dx.doi.org/10.1190/1.1444838.
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Geoelectric (dc) sounding methods are usually limited to electrode spacings smaller than 1 km, which restrict the depth of investigation to only several hundreds of meters. Greater depths of investigation require both a larger electrode spacing and motor‐generator driven transmitters. In order to increase the depth of investigation into the middle crust, the distance between transmitter and receiver dipole must be increased up to 100 km as well. Instead of a Schlumberger electrode configuration, we use a dipole‐dipole electrode arrangement, which avoids cable connections of several tens of kilometers. It takes less logistics in the field and requires less precautions to control the cable circuits. However, the electric field of a grounded dipole decays by the power of 3. Even if a strong current source with a power of 30 kW is employed, at distances beyond 10 km the amplitude of the transmitted dc signal becomes considerably smaller than the naturally inductive field and cultural noise. Here, we present a technique which resolves the transmitted dc signal at sites up to 60 km apart using an electric dipole source. The suggested technique removes the inductive part in the time series and, therefore, reduces the noise level. It requires applying the magnetotelluric technique before and/or after the geoelectrical sounding. Both the magnetic and electric variational fields are recorded during geoelectrical sounding. If the magnetotelluric transfer function is obtained at a site, then the natural inductive electric field can be predicted, which in turn is used to remove the inductive electrical part from the receiver dipole record.
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Carpenter, Chris. "Water-Based Drilling Fluid Helps Control Extreme Conditions in Gas Shale Play." Journal of Petroleum Technology 74, no. 11 (November 1, 2022): 62–64. http://dx.doi.org/10.2118/1122-0062-jpt.
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_ This article, written by JPT Technology Editor Chris Carpenter, contains highlights of paper URTeC 208307, “A Water-Based Drilling Fluid for Controlling Deep-Reservoir Extreme Conditions in an Abu Dhabi Gas Shale Play,” by Gabe Manescu, SPE, Schlumberger; Balazs Veer, SPE, TotalEnergies; and Panamarathupalayam Balakrishnan, SPE, Schlumberger, et al. The paper has not been peer reviewed. _ A combination of teamwork and fluids technology proved to be the formula for successfully drilling in high-pressure/high-temperature (HP/HT) conditions for an onshore UAE shale gas play. The success achieved in drilling deep [6200-m measured depth (MD)], long-lateral-displacement (2,000-m) wells with an integrated global operator is a combination dependent on frequent, transparent communication between team members. The environmentally acceptable aqueous drilling fluid delivered a barite sag-free operation in these highly deviated wellbores. Introduction The drilling of unconventional HP/HT wells in the Diyab field can experience difficulty in reaching target depth. One significant challenge is the design of a drilling fluid to manage reservoir pressures and temperatures. The reservoir temperature may reach 165.5°C, requiring mud weights (MW) greater than 20 lbm/gal. Tailoring the drilling-fluid formulation to balance economics and environmental regulations while overcoming HP/HT conditions is critical. In the Diyab drilling campaign, special emphasis was placed on designing the drilling fluid and then on its use in 8½-in. reservoir sections. Background The Upper Jurassic (Oxfordian to Middle Kimmeridgian) Diyab formation, also known as the Dukhan formation, has served as the source rock for several major oil and gas fields in the Middle East. The Diyab formation is unique because of its lower porosities, high carbonate mineralogy, and pressure gradient. Despite the lower porosity, the high-carbonate content defines an extremely brittle target conducive to hydraulic fracture stimulation. Several organic-rich intervals exist throughout the Diyab formation and are separated by less-organic tight limestones, which create different flow units. From a developmental perspective, this condition has the potential to create a high-impact stacked play. The extent of the prospective unconventional Diyab formation within the UAE is limited to the onshore north-central UAE, where most of this area is within Block 1, operated by TotalEnergies. The depth of the prospective basal Diyab interval across Block 1 ranges between 3758 and 4115 m. Three unconventional offset wells (DE-02, DE-03, and DE-04) were drilled by ADNOC within Block 1 to test the productivity of the three submembers of the greater Diyab interval (the Jubaila, Hanifa, and Tuwaiq Mountain formations). After determining that the Hanifa formation had the most-promising productivity, the first TotalEnergies appraisal horizontal well, DE-05, was drilled. After drilling this well, the DE-06 well was the second horizontal appraisal well to be drilled. Additionally, two more deep wells, DE-09 and DE-10, were successfully drilled and evaluated.
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Yusuf, Solomon Nehemiah, Hilnan Christopher Drenkat, and Charity Mamza Azi. "Groundwater Exploration Using Vertical Electrical Sounding And 2D Electrical Resistivity Tomography In Shale Formation: A Case Study Of Sabongida, Plateau State, North Central Nigeria." Warta Geologi 48, no. 1 (April 28, 2022): 10–22. http://dx.doi.org/10.7186/wg481202202.
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Sabongida is characterized by lots of abortive boreholes which are often shallow as a result of the complex nature of shale formation in the area and limited application of integrated geophysical techniques before drilling of boreholes. The presence of shale formation in the area makes it extremely difficult to drill productive boreholes, while the existing hand dug wells are always shallow due to the difficulty in digging deeper wells, this and other factors motivated the choice of the study location for the purpose of proffering solutions to solve the perennial water problem in the area. Twenty-two (22) vertical electric soundings data (VES) using Schlumberger array with the aid of Ohms mega resistivity meter were conducted with electrode spread of AB/2 = 215 m and eleven (11) 2D electrical resistivity tomography data (ERT) using ADMT – 600 S - X equipment were acquired. ERT was conducted using 20 m as the length of each profile with 300 m in 10 profile lines and 400 m as the depth of probing. The result of the VES interpretation shows three to five geo-electric layers while the geo-electric section revealed the aquifers to consist of sandstones with varying thicknesses. Two groundwater potential zones were delineated as shelly sandstones and clayey sand. The different color band indicates the different layers within the ground as the soil resistivity varies, blue indicates low resistivity values, green - yellow indicates moderate resistivity values while high resistivity values are brown - red. The results from the 2D images indicate the low resistivity regions, suggesting aquifer is within the depths of 150 to 300 m. Thus, the recommended depths for drilling of productive boreholes are 180 to 210 m and 270 to 300 m in Sabongida.
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Özcan, Ercan, Ali Osman Yücel, Sımon F. Mıtchell, Johannes Pıgnatti, Michael D. Simmons, Aral I. Okay, Levent Sina Erkızan, and Münire Nur Gültekin. "New Records of Caudriella Haman and Huddleston from the Middle and Late Eocene of Neo-Tethys: Taxonomic and Palaeobiogeographic Implications." Journal of Foraminiferal Research 52, no. 1 (January 20, 2022): 21–39. http://dx.doi.org/10.2113/gsjfr.52.1.21.
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ABSTRACT The middle to upper Eocene mixed carbonate-clastic and siliciclastic deposits of the Şevketiye and Keşan formations in northwest Turkey yielded unique assemblages of larger benthic foraminifera, some displaying a typical orbitoidiform test, not comparable to any known taxa in the Palaeogene of the Neo-Tethys. These specimens with a flat, discoidal test, occasionally with an indistinct central depression, possess a central layer of equatorial chambers/chamberlets displaying a cyclical (orbitoidal) growth pattern and thick lateral layers with numerous chamberlets. The megalospheric embryonic apparatus possesses three small chambers (a triconch, the chambers of which are separated by notably thin walls), followed by a large auxiliary chamberlet. These specimens closely correspond to the genus Caudriella Haman and Huddleston and its type-species Margaritella ospinae (Caudri) that has only previously been reported with confidence from the Caribbean region, notably the type locality within the middle Eocene Punta Mosquito Formation at Margarita Island off Venezuela. Caudriella at its type locality also possesses a trilocular embryonic apparatus, which was incorrectly interpreted as arranged in a rectilinear or slightly curved row. The diagnosis of Caudriella is emended and considering the similarities in their equatorial sections with closely associated Linderina Schlumberger, a comparison of their embryonic-nepionic stages is given from the same deposits in NW Turkey and with those from the middle Eocene of the Sulaiman Range (Pakistan) and Kutch (India). A new record of primitive Caudriella is presented from Jamaica. The palaeobiogeographic distribution of Caudriella is reconsidered, being recorded from both the American/Caribbean and the Western Neo-Tethys bioprovinces. Limited data suggest eastward directed dispersal of the genus, even though this would be counter to most of the prevailing surface currents during the Eocene.
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Shen, L. C., W. C. Savre, J. M. Price, and K. Athavale. "Dielectric properties of reservoir rocks at ultra‐high frequencies." GEOPHYSICS 50, no. 4 (April 1985): 692–704. http://dx.doi.org/10.1190/1.1441944.
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Conventional resistivity and induction tools measure the electrical conductivity of the formation. Interpretation of these logs is difficult in situations where the formation water resistivity is variable or unknown as a result, for example, of water, steam, or chemical flooding. Recent introduction of several dielectric tools offers a new technique in well logging. These sondes measure the relative dielectric permittivity of the formation at very‐high and ultra‐high radio frequencies. Because water has a much higher relative dielectric permittivity (about 80) than oil (about 2) or gas (about 1), the dielectric tool can distinguish hydrocarbon‐bearing zones from water‐bearing zones even when the formation fluid is nonconducting. However, in order to quantify the oil saturation in the formation, one needs an accurate formula that can relate the measured relative dielectric permittivity of the rock to the oil saturation in the rock. Present interpretation formulas have only a limited range of applicability. Therefore, our study was undertaken to answer the following question. Whereas Archie’s relationship relates the resistivity to oil saturation for resistivity logs, what is the corresponding saturation formula for dielectric logs? The approach we take is to measure core samples and obtain a broad data base from which we derive an interpretation formula. This paper describes how we developed a laboratory technique to measure reservoir core samples at ultra‐high frequencies, how the data are processed, and how an interpretation formula for water saturation is found. The data are obtained in the frequency range 800 to 1 200 megahertz (MHz), with the porosity of the rock ranging from 6 to 42 percent. The rocks are saturated with NaCl solution with salinity ranging from 0 to 182 000 ppm. Our study enabled us to develop a new and accurate interpretation technique for the dielectric tool called EPT (Electromagnetic Propagation Tool) manufactured by Schlumberger.
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Woobaidullah, ASM, M. Moklesur Rahman, and M. Zohir Uddin. "Evaluation of hydrogeological conditions through vertical electrical soundings survey at Mankiganj pourashava, Manikganj, central part of Bangladesh." Bangladesh Journal of Scientific Research 27, no. 2 (January 4, 2016): 109–20. http://dx.doi.org/10.3329/bjsr.v27i2.26229.
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The Pourashava area of Manikganj, located in the central part of Bangladesh is treated as arsenic hotspot in the country as the outcome of various studies concludes that almost 80% of the domestic tube wells at this area exceed arsenic level of Bangladesh standard (50 ?g/l) for drinking water. To enhance the potable water supply in the area, 15 geoelectric soundings survey using Schlumberger configuration with spreading AB/2 = 300 meters has been executed to decipher the subsurface lithology distribution and aquifers at different depths, to determine the lateral and vertical extent of aquifer at the area. Correlation of the analyzed VES results with primary and secondary borelogs, the subsurface sequence of the area is broadly divided into two geoelectric units. Firstly, the near surface geoelectric unit of resistivity less than 20.0 ?-m represents the top soil composed of silty clay to clay. The thickness of this layer varies from 1 meter to 5 meters. The second geoelectric unit represents the sand layer and is characterized by a resistivity range of 21.0 to 190.0 ?-m. This unit encompasses the very fine sand with variable thickness of 2 to 248m while resistivity is from 21.0 to 30.0 ?-m, very fine to fine sand having thickness from 174-280m and geoelectric value ranges from 31.0 to 40.0 ?-m, fine sand with resistivity from 44.0 to 50.0 ?-m, fine to medium sand having resistivity from 51.0 to 70.0 ?-m, medium sand and medium to coarse sand with resistivity value 75.0 to 110.0 ?-m, and 140.0 to 190.0 ?-m, respectively. The ultimate thickness of this unit could not be determined due to limited spread of survey but at least continues to a depth of 300 m. In the context of groundwater storage, the second geoelectric unit acts as the regional aquifer and is used for groundwater development in the Pourashava area for water supply.Bangladesh J. Sci. Res. 27(2): 109-120, December-2014
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Woobaidullah, A. S. M., and Mohammad Zohir Uddin. "Geoelectric resistivity sounding for deciphering hydrogeology and locating deep tubewell installation sites in Puroshava area of Bagerhat, Bangladesh." Journal of Nepal Geological Society 42 (September 24, 2011): 107–16. http://dx.doi.org/10.3126/jngs.v42i0.31458.
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The study area includes Bagerhat Pouroshava and its surroundings under Bagerhat Sadar Upazila covering an area of 7.53 sq. km with a population of about 50,000. Bagerhat is a coastal district and the subsurface geology is complicated. As in other areas of the coastal belt the quality of ground water in the area is also variable. For ground water development in the study area the shallow aquifer is not suitable as the water is mostly saline to brackish except some isolated fresh water pockets of limited yielding capacity. The deep aquifer is also not very homogeneous in water quality. In the northwestern part it bears fresh water but water quality deteriorates south-southeast with higher depth of occurrence. A comprehensive study is carried out to demarcate the aquifers and to judge the water quality to find the suitable location of the deep tube wells in Bagerhat Pouroshava area.
Fifteen geoelectric soundings have been executed in the study area using Schlumberger configuration with maximum spreading of 1200 m. Based on the vertical electrical sounding interpretation results the subsurface sequence is divided into following geoelectric units: The top unit has resistivity less than 5.0 Ωm with a thickness of 1.5 to 20 m and represents the top clay silty/sandy clay layer. The second geoelectric unit represents a very fine to medium sand with thin clay lenses and resistivity varying from 5.0 Ωm to more than 100.0 Ωm with a thickness of 16 to 135 m. The resistivity of the following unit ranges from l.40 Ωm to 4.8 Ωm and thickness varies from 100 m to more than 300 m. The deepest geoelectric unit shows resistivity from 8.0 Ωm to 18.0 Ωm and represents the deep aquifer. The depth to the aquifer varies from 235 m to 355 m. The most suitable site for groundwater development from the deep aquifer is in the vicinity of East Saira of Shatgambuj union.
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Poddar, M., and Walter L. Anderson. "Transient electromagnetic modeling of shallow A‐type sections with 3-D inhomogeneities." GEOPHYSICS 57, no. 6 (June 1992): 774–80. http://dx.doi.org/10.1190/1.1443291.
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A hard rock area underlain by granitic/gneissic or basaltic rocks often has an A‐type three‐layer geoelectric section in which resistivity increases with depth. The middle layer of moderate resistivity caused by fracturing/fissuring that lies between the surface‐weathered layer and the substratum of unfractured rock is not a good target for a direct current (DC) resistivity sounding since it is generally suppressed in the observations. Moreover, its definition requires expanding the electrode spacing to a length several times the depth of the target layer, and this may be a drawback if the target layer is either laterally variable or limited in its horizontal extent. We first studied the transient electric field of a horizontal electric dipole (HED) source excited by a step turn‐off current for a 1-D model of an A‐type geoelectric section. The results of this theoretical study are presented as graphs of normalized apparent resistivity versus a time‐related dimensionless parameter. Irrespective of the separation between the transmitter and receiver dipoles, these transient sounding curves become similar to the corresponding Schlumberger sounding curves at late time. Hence the transient electric field measurement offers the possibility of sounding at a fixed transmitter‐receiver spacing that may be shorter than the target depth. Also, at early times, for a certain ratio of the dipole separation to the target depth, there is a dramatic increase in the resolution of the response. Thus, it is possible to resolve suppressed layers of an A‐type section in this type of sounding. A study of the effects of transmitter ramp time and receiver bandwidth on the transient apparent resistivity curves shows that a very fast current shut‐off and wideband measurement are required to realize all the possibilities suggested by this modeling. Some 3-D transient electromagnetic (TEM) modeling was also done to simulate (1) a lateral variation in the resistivity of the middle layer of an A‐type section and (2) a weak zone of limited horizontal extent in the substratum of a two‐layer section. We observed that the 3-D inclusion has less effect at late time but is more pronounced at early time. In view of the above results, we conclude that the transient E‐field sounding with a grounded wire source can be used in place of a conventional DC resistivity sounding to overcome the problem of poor resolution due to the suppression of the intermediate layer in a geoelectric section where the resistivity increases with depth. As such, it has a potential application in groundwater as well as geotechnical surveys, because together with the overlying weathered layer, the fractured rock constitutes the aquifer in hard rocks.
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Han, Choongyong, Mojdeh Delshad, Kamy Sepehrnoori, and Gary Arnold Pope. "A Fully Implicit, Parallel, Compositional Chemical Flooding Simulator." SPE Journal 12, no. 03 (September 1, 2007): 322–38. http://dx.doi.org/10.2118/97217-pa.
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Summary A fully implicit, parallel, compositional reservoir simulator has been developed that includes both a cubic equation of state model for the hydrocarbon phase behavior and Hand's rule for the surfactant/oil/brine phase behavior. The aqueous species in the chemical model include surfactant, polymer, and salt. The physical property models include surfactant/oil/brine phase behavior, interfacial tension, viscosity, adsorption, and relative permeability as a function of trapping number. The fully implicit simulation results were validated by comparison with results from our IMPEC chemical flooding simulator (UTCHEM). The results indicate that the simulator scales well using clusters of workstations. Also, simulation results from parallel runs are identical to those using a single processor. Field-scale surfactant/polymer flood simulations were successfully performed with over 1,000,000 gridblocks using multiple processors. Introduction Chemical flooding is a method to improve oil recovery that involves the injection of a solution of surfactant and polymer followed by a polymer solution. The surfactant causes the mobilization of oil by decreasing interfacial tension, whereas the polymer increases the sweep efficiency by lowering the mobility ratio. Chemical flooding has the potential to recover a very high fraction of the remaining oil in a reservoir, but the process needs to be designed to be both cost effective and robust, which requires careful optimization. Several reservoir simulators with chemical flooding features have been developed as a tool for optimizing the design (Delshad et al. 1996; Schlumberger 2004; Computer Modeling 2004). The University of Texas chemical flooding simulator, UTCHEM (Delshad et al. 1996) is an example of a simulator that has been used for this purpose. However, because UTCHEM is an Implicit Pressure and Explicit Concentration (IMPEC) formulation and in its current form cannot run on parallel computers, realistic surfactant/polymer flooding simulations are limited to around 100,000 gridblocks because of small timestep restrictions and insufficient memory. Recently, the appropriate chemical module was added to the fully implicit, parallel, EOS compositional simulator called GPAS (General Purpose Adaptive Simulator) based on a hybrid approach (John et al. 2005). GPAS uses a cubic equation of state model for the hydrocarbon phase behavior and the parallel and object-based Fortran 95 framework for managing memory, input/output, and the necessary communication between processors (Wang et al. 1999; Parashar et al. 1997). In the hybrid approach implemented in GPAS, the material balance equations for hydrocarbon and water components are solved implicitly first. Then, the material balance equations for the aqueous components such as surfactant, polymer, and electrolytes are solved explicitly using the updated phase fluxes, saturations, and densities.
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Leytur, Matías, Esteban Gandolfo, Danilo Carnelos, Ernesto Giardina, and Adalberto Di Benedetto. "Biomass accumulation of Schlumbergera truncata (Haw.) Moran (Thanksgiving cactus) grown under high pot density." Journal of the Professional Association for Cactus Development 23 (September 17, 2021): 121–33. http://dx.doi.org/10.56890/jpacd.v23i.331.
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The growth of most pot-grown succulents offered by the ornamental industry is limited mainly by water, nutrients, photoperiod, and temperature manipulation, while other decisions, such as: plant density at pot cropping are often based on the grower’s experience. In the present study, to optimize the biomass accumulation of Schlumbergera truncata under high pot density, we performed an experimental design that included different numbers of initials phylloclades and spraying or not with the synthetic cytokinin 6-benzylaminopurine (BAP). The highest biomass accumulation on a fresh weight basis and highest stem area expansion were recorded in pots with five initial phylloclades and BAP-sprayed plants. The decrease in individual biomass accumulation and the expansion of steam area were related to an increase in pot density. Since shading effect can be discard, responses to photo-assimilate uptake and distribution more associated with mechanical constraints on pot roots rather than with a competition between individual roots. Our results suggest that, when Schlumbergera truncata is grown in pots, the number of initial phylloclades may be higher than the usually recommended number per pot.
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Carpenter, Chris. "Machine Learning Aids Early Detection of Stuck Pipe in Extended-Reach Wells." Journal of Petroleum Technology 74, no. 05 (May 1, 2022): 82–84. http://dx.doi.org/10.2118/0522-0082-jpt.
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This article, written by JPT Technology Editor Chris Carpenter, contains highlights of paper SPE 206516, “Stuck-Pipe Early Detection in Extended-Reach Wells Using Ensemble Method of Machine Learning,” by Rushad Ravilievich Rakhimov, SPE, Schlumberger, and Oleg Valerievich Zhdaneev, SPE, and Konstantin Nikolaevich Frolov, SPE, Ministry of Energy of the Russian Federation, et al. The paper has not been peer reviewed. The objective of this paper is to describe the experience of using a machine-learning model prepared by the ensemble method to prevent stuck-pipe events during construction of extended-reach wells. The tasks performed include collecting, analyzing, and cleaning historical data; selecting and preparing a machine-learning model; and testing it on real-time data by means of a desktop application. The idea is to display the solution at the rig floor, allowing the driller to take actions quickly for prevention of stuck-pipe events. Problem Analysis Packoff is the blockage of the annular space with drilled cuttings or parts of rocks fallen from wellbore walls. In a packoff situation, circulation is severely limited or impossible. With an inadequate response to packoff, fracturing of rocks below the bottomhole assembly (BHA) can occur, which leads to losses of drilling fluid and possible kick. In addition to time spent and technological risks, high expense is possible. In a worst-case scenario, the BHA can be left in hole and the bore must be redrilled, leading to a multimillion-dollar financial loss caused by nonproductive time. Packoff events fall mainly into two categories: - Caused by a cuttings bed that occurs when drilled cuttings are caught up while backreaming out of hole too promptly - Caused by wellbore collapse because of insufficient mud properties During the past 10 years, 28 wells have been drilled in the field of interest. Two hundred and twenty-seven incidents associated with stuck-pipe events have been registered. The light cases required an additional rereaming of the problematic interval, with a loss of time of up to 20 minutes. The most severe cases resulted in multimillion-dollar financial losses because of the BHA being lost in hole and the time spent on redrilling the wellbore. Classification of the incidents showed that 24 cases (11%) belong to the differential type of sticking, while 17 cases (8%) belong to the wellbore-geometry type and 186 cases (81%) to packoff events. The data collected at the field show that packoffs were encountered only during backreaming operations. Packoffs evolve rapidly. Thus, in most cases on the studied field, the time interval between trouble-free operation and sticking events is between 20 and 90 seconds (Fig. 1). Unlike physical modeling methods, machine-learning methods serve as a base for development of tools that work solely from historical data, allowing a more-precise simulation of real parameter behavior. Another advantage of machine-learning methods is the ability to select only the best historical cases for use. However, the use of historical data for prediction of downhole accidents in the well-construction process is not a novel approach. It has been used in the industry for more than 30 years. The complete paper includes an extensive discussion of examples in the literature.
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Soller, André, Patrícia Soffiatti, Alice Calvente, and Renato Goldenberg. "Cactaceae no estado do Paraná, Brasil." Rodriguésia 65, no. 1 (March 2014): 201–19. http://dx.doi.org/10.1590/s2175-78602014000100014.
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Este trabalho apresenta o estudo taxonômico de Cactaceae no estado do Paraná. A metodologia inclui a análise de coleções de herbário e realização de coletas em todos os biomas do estado. Doze gêneros e 26 espécies nativas foram inventariados para o estado. Os gêneros mais ricos são Rhipsalis, representado por 11 espécies, Lepismium (4) e Schlumbergera (2). Os outros nove gêneros estão representados por apenas uma espécie cada: Brasiliopuntia brasiliensis, Cereus hildmannianus, Epiphyllum phyllanthus, Hatiora salicornioides, Hylocereus setaceus, Opuntia monacantha, Parodia carambeiensis, Pereskia aculeata e Praecereus euchlorus. O Paraná representa o limite norte de ocorrência no Brasil de S. rosea e S. gaertneri e limite sul de ocorrência de B. brasiliensis, H. salicornioides e R. pilocarpa . Parodia carambeiensis é a única Cactaceae endêmica do estado. São apresentadas descrições, chaves para identificação de gêneros e espécies, ilustrações e comentários taxonômicos.
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Hunter, Aaron W., and Neil D. L. Clark. "The palaeoecology of two Scottish encrinites: Jurassic crinoid assemblages from the Trotternish Peninsula, Isle of Skye, Scotland." Scottish Journal of Geology 45, no. 2 (October 1, 2009): 169–76. http://dx.doi.org/10.1144/0036-9276/01-366.
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SynopsisDespite a long history of investigation, articulate crinoids from the Jurassic of Scotland have not received great attention compared to their counterparts in Southern England or continental Europe; this is thought to be largely due to poor preservation. Two examples of ‘local’ encrinites (rocks almost entirely composed of crinoids debris), one from the Pliensbachian and the other from the Aalenian/Bajocian from the Isle of Skye, are shown to consist of columnals of Hispidocrinus cf. schlumbergeri and Balanocrinus donovani respectively. They represent local encrinites that have been deposited parautochthonously; one in a proximal, and the other in a more offshore low energy environment. This demonstrates that even limited encrinite material can not only be assigned systematically, but can also be used to reconstruct the original palaeoenvironments that the crinoids inhabited.
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Ramirez, Dario, and Harvey J. Lang. "Effect of Iron Concentration on Growth and Phylloclade Edge Yellowing of Holiday Cactus." HortScience 30, no. 4 (July 1995): 866B—866. http://dx.doi.org/10.21273/hortsci.30.4.866b.
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Production of holiday cactus has been limited by the common occurrence of marginal chlorosis of the phylloclades, which can lead to losses in crop quality. This work was conducted to determine if poor growth and phylloclade yellowing could be correlated to applied Fe concentration. Rooted cuttings of Schlumbergera truncata `White Christmas', `Twilight Tangerine', 'Christmas Charm', and `Lavender Doll' were transplanted into a modified Hoagland's solution, adjusted to a pH of 6.3, containing Fe-EDTA at either 0,10,20,30, or 40 mg·liter–1 Fe. Plants were grown in a controlled environmental chamber under 16 h daylength for 16 weeks at 22/18C day/night temperature. Plants grown under 0 and 10 mg·liter–1 Fe had significantly greater fresh weight, height, and root length than plants grown under higher Fe concentrations for all cultivars. Comparison of tissue analysis results revealed a direct correlation between poor growth and levels of Fe within the tissue. There was no correlation, however, between Fe concentration and phylloclade edge yellowing, as yellowing occurred sporadically in all treatments. Comparison studies in the greenhouse of plants grown in peat: perlite medium showed similar trends.
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Carvalho, João Da Silva, Javier Tomasella, Shozo Shiraiwa, and Rutenio Luiz Castro de Araujo. "STRATIGRAPHIC ASPECTS OF THE ALTER DO CHÃO FORMATION IN THE NORTHERN REGION OF MANAUS, BASED ON GEOELECTRIC INFORMATION." Revista Brasileira de Geofísica 32, no. 1 (March 1, 2014): 61. http://dx.doi.org/10.22564/rbgf.v32i1.397.
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ABSTRACT. The geoelectrical survey was conducted in a portion of the northern edge of the Amazon Sedimentary Basin, between the kilometer 38 and the kilometer 96 of the BR-174 highway, dominated by sediments of the Alter do Chão Formation. We performed eight vertical electrical soundings (Schlumberger) and an electrical imaging section (dipole-dipole), using a portable resistivity (Syscal R2). The field data were processed using IPI2Win and RES2DINV softwares, resulting in the development of profiles and sections of electrical resistivity, which allowed the identification of lithologies and structures (faults) that affected this lithostratigraphic unit, as well as their contact relations with the rocks of the Manacapuru Formation, in this portion of land. In the Alter do Chão Formation, the highest resistivities are related to weathered materials of the superficial layers and sandstone in the deeper strata, which appear interspersed with thin layers of pelitic material. The results of electrical imaging performed in the portion of the northern boundary of Alter do Ch˜ao Formation, show the horizontal behavior of strata, highlights geological features (faults) and the south slope of its substrate, towards the center of the basin.Keywords: geological features, lithology, electrical resistivity. RESUMO. O levantamento geoelétrico foi realizado em uma porção da borda norte da Bacia Sedimentar do Amazonas, entre os quilômetros 38 e 96 da rodovia BR-174, onde predominam exposições sedimentares da Formação Alter do Chão. Foram realizadas oito sondagens elétricas verticais (Schlumberger) e uma seção de imageamento elétrico (Dipolo-dipolo), por meio de um resistivímetro portátil (Syscal R2). Os dados de campo foram processados por meio dos softwares IPI2Win e RES2DINV, que resultaram na elaboração de perfis e seções de resistividade elétrica, o que permitiu a identificação de litologias e estruturas (falhas) que afetaram as rochas dessa unidade litoestratigráfica, assim como suas relações de contato com as rochas da Formação Manacapuru, nessa porção territorial. No âmbito da Formação Alter do Chão, as resistividades mais elevadas estão relacionadas com materiais de alteração, nas camadas mais superficiais, e a estratos arenosos mais profundos, os quais aparecem intercalados com finas camadas de material pelítico. Os resultados do imageamento elétrico, realizado na porção do limite norte da Formação Alter do Chão, mostram o comportamento horizontal dos estratos, e destacam feições geológicas (falhas) e a declividade para sul do seu substrato, no sentido para o depocentro da bacia.Palavras-chave: feições geológicas, litologias, resistividade elétrica.
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Lima, Olivar Antônio Lima de. "GEOPHYSICAL CHARACTERIZATION OF AQUIFERS IN THE SALITRE RIVER BASIN, BAHIA STATE, BRAZIL, USING RESISTIVITY SOUNDINGS AND ELECTRICAL TOMOGRAPHIES." Revista Brasileira de Geofísica 32, no. 4 (December 1, 2014): 637. http://dx.doi.org/10.22564/rbgf.v32i4.552.
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ABSTRACT. The Salitre River basin, which is located in the semi-arid land of northeastern Brazil, is annually faced with severe surface-water scarcity. Twomain aquifersystems, which are distributed in depth, can be exploited to supply the water needs of the population and its present agro-industrial development: (i) a fractured-karst,water-table component, totally developed within the upper carbonate sequence of the Salitre Formation; and (ii) a fractured-clastic, semi-confined component, mostlikely associating lower Salitre limestones with the meta-sandstones of the Morro do Chap´eu Formation. Geophysical efforts have been useful in developing a regional,three-dimensional characterization of these two aquifer components of the Salitre river aquifer system and in detailing a useful electric tomographic scheme to implementtheir exploration. The geophysical survey, which comprised 64 Schlumberger electrical soundings of resistivity and five tomographic sections, was combined with welldata to define the geometric and hydraulic characteristics of these aquifer components. The inversion of the resistivity data, under the control of the well data, was usefulto reduce electrical ambiguities and to better define the depth of the water table and that of the thick, impervious aquifer substrate. The lateral and depth boundaries of thefracture-karst aquifer zones were outlined, allowing the estimation of a total reserve of approximately 100 billion m3 of groundwater. Chemical analysis of water samplescollected at production wells was used to define a water quality zoning within the basin. These results are very important to define an optimum exploration regime for thegroundwater available in the basin.Keywords: electrical sounding, tomographic section, Salitre aquifer system. RESUMO. A bacia hidrogáafica do rio Salitre faz parte da região semiárida da Bahia e, por isso, apresenta severa escassez de água superficial. Dois principais componentes aquíferos, distribuídos em profundidade, podem ser explorados para suprir as necessidades hídricas da população humana e de seu incipiente desenvolvimento agroindustrial: (i) um componente cárstico-fraturado, de natureza livre, desenvolvido nas rochas carbonáticas superiores da Formação Salitre; e (ii) um componentefraturado, semi-confinado, combinando rocha basais da sequência Salitre e unidades meta-quartzíticas da Formação Morro do Chapéu. Foram executadas 64 sondagens elétricas verticais usando o arranjo Schlumberger de eletrodos, centradas em pontos selecionados da bacia, e cinco seções tomográficas de resistividade, para detalhara estrutura subsuperficial de locais selecionados. A inversão dos dados de resistividade aparente, com controle de informações de poços, foi útil para reduzir ambiguidades elétricas e melhor definir as profundidades do nível estático e do topo do espesso substrato impermeável do sistema aquífero Salitre. Esses estudos permitiramavaliar, regionalmente, os recursos hídricos subterrâneos da bacia, em termos de geometria e características hidráulicas, bem como propor um procedimento para efetuar tomografia elétrica bidimensional, visando sua efetiva exploração por meio de poços. Os limites laterais e em profundidade das zonas de maior carstificação e de densos fraturamentos foram delineados, possibilitando estimar uma reserva total de água no sistema do rio Salitre em cerca de 220 bilhões de m3. Análises físico-químicas deamostras de água coletadas em poços foram usadas para caracterizar a variabilidade na qualidade da água subterrânea na bacia. Tais resultados podem ser usados paraplanejar um regime de exploração eficiente e conservativo das reservas de água subterrânea disponíveis.Palavras-chave: sondagem elétrica, seção tomográfica, sistema aquífero Salitre.
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Santosa, Langgeng Wahyu, and Tjahyo Nugroho Adji. "The Investigation of Groundwater Potential by Vertical Electrical Sounding (VES) Approach in Arguni Bay Region, Kaimana Regency, West Papua." Forum Geografi 21, no. 1 (May 14, 2016). http://dx.doi.org/10.23917/forgeo.v21i1.1820.
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This research was conducted within some villages in the surrounding area that administratively including Arguni Bay District, Kaimana Regency, West Papua. The main objective of this study is to vertically measure resistivity value of aquifer with the intention of recognizing deep groundwater potency as a source of native’s domestic needs. In addition, VES method by Schlumberger electrode array was applied within 18 locations, which expectantly represent the whole area of research. The resistivity data is then interpreted by IP2Win 2.1 Geoelectric Software to entirely describe the aquifer system as well as the occurrence of groundwater. The result indicates that vertically, the aquifer system is dominated by interbedded of claystone and sandstone (argillite group) as a past marine environment mineral. In addition, geomorphological and resistivity sounding interpretation gives a viewpoint that the landforms of the research area may be typified as Structural Mountain with the slope direction is towards the island beaches. Also, structurally, the main groundwater system is fractured aquifer with very limited productivity of groundwater resources. As consequences, this aquifer is more to be an aquitard, rather than an aquifer.
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Tadeu Carvalho do Nascimento, Carlos, José Vicente Elias Bernardi, Andreia De Almeida, João Cândido Magalhães, and Paulo Milton Barbosa Landim. "GEOELECTRICAL MODEL FOR AQUIFER IN THE BONITA LAKE REGION, PLANALTINA, DISTRITO FEDERAL, BRAZIL." Revista Brasileira de Geofísica 35, no. 1 (February 21, 2017). http://dx.doi.org/10.22564/rbgf.v35i1.767.
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ABSTRACT. The aim of this study was to analyze the soil geoelectric behavior, through geophysical surveys, in the surrounding region to Bonita Lake, a natural reservoir located in the Ecological Station águas Emendadas (ESECAE), 50 kilometers from Brasília (Brazil). Sixteen vertical electrical sounding (VES) were performed with Schlumberger array. The geoelectrical model, obtained by inversion of the field data and statistical analysis of the inverted data, indicated structure with superficial dry soil above partially saturated layer, and finally a soil or rock with low permeability, related to the aquifer formation with varying thickness, about ten meters below the lake and up to twenty meters deep in the surrounding area. The VES showed that the aquifer has great lateral extension to the north, east and west of the lake; providing water to the same, while in the south, the aquifer is possibly limited by quartzites of the Canastra Group. This restriction can result in the absence of aquifer recharge in the southern portion, and coincides with the region where the lake drains into the source of Mestre D’Armas stream. This information is important because it can be used in the delineation of the hydrogeological basin and the Bonita Lake protection perimeter. Keywords: Ecological Station of águas Emendadas, aquifer, geophysics, vertical electrical soundings. RESUMO. O objetivo deste estudo foi analisar o comportamento geoelétrico do solo, por meio de levantamentos geofísicos, na região circundante à Lagoa Bonita, um reservatório natural localizado na Estação Ecológica de águas Emendadas (ESECAE), a 50 quilômetros de Brasília (Brasil). Dezesseis sondagens elétricas verticais (SEV) foram realizadas com arranjo de Schlumberger. Os modelos geoelétricos, obtidos pela inversão dos dados de campo e análise estatística dos dados invertidos, indicaram uma estrutura com solo superficial seco sobreposto a uma camada parcialmente saturada e, por fim, um solo ou rocha com baixa permeabilidade, referente a formação aquífera, com espessura variável, cerca de dez metros abaixo da lagoa e até vinte metros de profundidade na área circundante. As SEV demonstraram que o aquífero possui grande extensão lateral para norte, leste e oeste da lagoa; fornecendo água para a mesma, enquanto que, na direção sul, o aquífero é possivelmente limitado por quartzitos do Grupo Canastra. Esta restrição pode resultar na ausência de recarga do aquífero na porção sul, e coincide com a região onde a lagoa drena para a nascente do ribeirão Mestre D’Armas. Esta informação é importante, pois pode ser utilizada no processo de delimitação da bacia hidrogeológica e delimitação do perímetro de proteção da lagoa Bonita. Palavras-chave: Estação Ecológica de águas Emendadas, aquífero, geofísica, sondagem elétrica vertical.
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Afuekwe, Austin, and Kelani Bello. "Use of Smart Controls in Intelligent Well Completion to Optimize Oil & Gas Recovery." Journal of Engineering Research and Reports, June 10, 2019, 1–14. http://dx.doi.org/10.9734/jerr/2019/v5i416930.
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For the past few years, the oil and gas industry has faced several economic, geographic and technical challenges largely due to decline in crude oil prices and market volatility.
In the quest to address some of these challenges to accelerate production and subsequently maximize ultimate recovery, operators are limited to remote hydraulic and electro-hydraulic monitoring and control of safety valves providing the means of obtaining downhole production data which demands periodic well intervention-based techniques with risk of loss of associated tools. This has highlighted the need for companies to adopt new technology to take advantage of low crude oil price environment, optimizing recovery without interventions and with minimal production interruption.
One of the recent improvements in production technologies which can remedy these problems having unique capabilities to do so is the Intelligent Well Completion (IWC) technology. In this paper the utilization of IWC to optimize oil recovery was evaluated. The use of a reservoir simulator, the Schlumberger ECLIPSE-100 simulator, was employed to model an intelligent well. Case study simulations were performed for an active bottom-water drive. Modeling of the Intelligent Well Inflow Control Devices (ICDs) and downhole sensors for the multilaterals was achieved using the Multi-Segment Well model.
Optimal IWC technology combination for maximum hydrocarbon recovery and minimal water production was determined using the reactive control strategy (RCS) which indicated a drastic reduction of about 52.1% in water production with a slight drop of 1.5% in field oil efficiency (FOE). The simulation results obtained clearly showed that the utilization of intelligent well-ICDs in Production wells can significantly increase the cumulative oil production and reduce water production.
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Jekayinfa, Solomon M., Michael A. Oladunjoye, and Kennedy O. Doro. "Imaging the distribution of bitumen contaminants in shallow coastal plain sands in southwestern Nigeria using electrical resistivity." Environmental Earth Sciences 82, no. 2 (January 2023). http://dx.doi.org/10.1007/s12665-022-10718-w.
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AbstractNaturally occurring bitumen seeps migrating within the shallow subsurface contaminates soil and groundwater in communities within the eastern segment of the Dahomey Basin in southwestern Nigeria. Managing these contaminations require an understanding of the distribution of the bitumen seeps to isolate contaminated regions to avoid farming activities or drilling shallow drinking water wells within them. Several studies have assessed the shallow occurrence of bitumen in the region, focusing on their economic potentials but ignores the challenges with soil and groundwater contamination in these communities. This study focuses on using electrical resistivity imaging techniques with limited soil cores to delineate the distribution of bitumen seeps within the shallow subsurface in Imakun-Omi community in southwestern Nigeria. We used both 1D and 2D numerical and field approaches in this study. 13 vertical electrical soundings using a Schlumberger electrode array were first acquired to obtain the bulk resistivities and layer thicknesses. The 1D resistivity alongside well lithologic data served as prior data for a forward modelling study to assess the capability of resolving the bitumen seeps within electrically resistive coastal sands. Results of the forward modelling studies guided the acquisition of five 2D electrical resistivity profiles used to image the distribution of bitumen seeps using a Wenner electrode array with a unit electrode spacing of 2 m. Results of this study show that bitumen seeps with resistivities greater than 3000 Ohm-m are distributed within the top 4 m in the area and extends down to 10 m in some locations. Our numerical studies show that despite difficulties in imaging bitumen seeps within sediments overlain by higher electrical resistivity layers, reliable results can be derived, thus proving the versatility of electrical resistivity in delineating areas contaminated by bitumen seeps within shallow coastal sands.
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Moradi, Ali, and Britt M. E. Moldestad. "A Proposed Method for Simulation of Rate-Controlled Production Valves for Reduced Water Cut." SPE Production & Operations, April 1, 2021, 1–16. http://dx.doi.org/10.2118/205377-pa.
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SummaryIn recent years, the advancement of horizontal-well technology has played a major role in making oil production economically feasible from many reservoirs. One of the major problems that can reduce the efficiency of using horizontal wells is gas and water coning caused by the heel-toe effect and heterogeneity along the well. To tackle this problem, Equinor’s autonomous inflow-control device (ICD) (AICD), known as rate-controlled production (RCP) valves, is widely used today. RCP valves can effectively delay the early water breakthrough and partially choke back water autonomously after water breakthrough. To fulfill a suitable design of a long horizontal well with the RCP completion, a detailed understanding of multiphase-flow behavior from the reservoir pore to the wellbore and production tubing is needed. Coupling a dynamic multiphase-flow simulator such as the OLGASM (Schlumberger Limited, Sugar Land, Texas, USA) simulator with the near-wellbore reservoir module such as the OLGA ROCX module provides a robust tool for achieving this purpose. However, there is no predefined option in the OLGA simulator for implementing the autonomous behavior of the RCP valves directly. Therefore, creating a model of oil production by considering well completion with the RCP valves in the OLGA simulator is challenging. In the previous works, this has been performed by using the Proportional Integral Derivative (PID) Controller option in the OLGA simulator, which controls the opening of an equivalent orifice valve according to the fixed value of the water cut. However, because of the performance of the PID Controller using a fixed setpoint and the difficulties in properly tuning the PID Controller, choosing this option leads to a large degree of inaccuracy in the simulation models. In this paper, by proposing a novel method with a developed mathematical model and a control function for the RCP valves, the autonomous behavior of these valves is implemented in the OLGA simulator. In this new approach, the control signals are calculated using the variation of water cut and introduced to the OLGA simulator through the Table Controller option instead of the PID Controller. The presented approach in this paper can be used for the simulation of water-cut (or gas/oil-ratio) reduction potential of all RCP-type AICDs in reservoirs with different characteristics. However, to explain the procedure of this approach in detail, the near-well oil production from Well 16/2-D-12 in the Johan Sverdrup Field (JSF) considering RCP completion is modeled as a case study. In this study, the simulation model is developed using one of the commonly used types of RCP valves called the TR7 RCP valve. Version 2016.1.1 of the OLGA simulator/ROCX module is used (Schlumberger 2016). According to the simulation results, compared with using ICDs, by the completion of Well 16/2-D-12 with RCPs, the water cut, water-flow rate, and accumulated water production can be reduced by 2.9, 13.3, and 12.1%, respectively, after 750 days. The results also showed that by using the proposed approach, the autonomous behavior of the RCP valves according to the water-cut variations can be appropriately implemented in the OLGA simulator. This can help engineers and researchers to achieve a better design of a long horizontal well using the RCP completion. Consequently, using this approach can be beneficial for improving technology, optimizing production, minimizing risk, and reducing costs in oil recovery.
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Ibuot, J., G. Akpabio, and N. George. "A survey of the repository of groundwater potential and distribution using geoelectrical resistivity method in Itu Local Government Area (L.G.A), Akwa Ibom State, southern Nigeria." Open Geosciences 5, no. 4 (January 1, 2013). http://dx.doi.org/10.2478/s13533-012-0152-5.
Full textAbstract:
AbstractVertical electrical sounding (VES), employing a Schlumberger electrode configuration, was used to investigate the sediments and aquifer repositories in Itu Local Government Area of Akwa Ibom state, southern Nigeria. This was done in sixteen (16) locations/communities with the maximum current electrode spread ranging between 800–1000m. The field data were interpreted using forward and iterative least square inversion modeling, which gives a resolution with 3–5 geoelectric layers. The observed frequencies in curve types include 31.25% of AKH, 18.8% of AAK and HK and 6.25% of K, QHK, AKH, KA and KHQ, respectively. These sets of curves show a wide range of variabilities in resistivities between and within the layers penetrated by current. The presence of K and H curve types in the study area indicates the alteration of the geomaterials with limited hydrologic significance to the prolific groundwater repository. A correlation of the constrained nearby borehole lithology logs with the VES results shows that the layers were all sandy formations (fine and well sorted sands to gravelly sands or medium to coarse-grained sands as described by nearby lithology logs) with some wide ranges of electrical resistivity values and thicknesses caused by electrostratigraphic inhomogeneity. The geologic topsoil (motley topsoil) is generally porous and permeable and as such the longitudinal conductance (S) values for the covering/protective layer is generally less than unity of Siemens (S < 1Ω−1), the value considered for efficient protection of the underlying aquifers by the topmost and overlying layer. The spatial orientations and the leveling patterns of the most economically viable potential groundwater repository within the maximum current electrode separations has been delineated in 2-D and 3-D contoured maps. The estimated depth range for the desired groundwater repository is 32.6–113.1m and its average depth value is 74.30m. The thickness of this layer ranges from 27.9–103m while its average depth has been evaluated to be 63.02m. Also, its resistivity range and average value have been estimated to be 507–5612m and 3365.125Ωm
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Agyemang, Victor Ofori. "Geophysical investigation of groundwater potential and aquifer protective capability in selected communities within Cape Coast municipality, Ghana." Applied Water Science 12, no. 2 (January 28, 2022). http://dx.doi.org/10.1007/s13201-021-01558-3.
Full textAbstract:
AbstractApplication of VES geophysical technique to investigate the groundwater potential and the aquifer protective capability has been carried at Cape Coast Municipality, Ghana. The geology of Cape Coast is mainly made of the Secondian formation and the Eburnean Plutonic Suite. Twenty (20) VES points were selected after the profiling, and Schlumberger array was applied for the conduction of the VES. The PASI Resistivity Terrameter was used, and the maximum current electrode spacing (AB/2) was 100 m. Partial curve matching technique and computer iteration technique were applied in the interpretation data using WINRESIST software. The thematic maps of the parameters were generated to display their spatial variations using Surfer Golden software by the application of appropriate variograms depending on their range of values. The study revealed the presence of three to six layers curve types which include HKH (45%), QH (20%), HA (10%), KH (5%), QHKH (5%), A (5%), AKH (5%) and KHKH (5%) in the study area. The layers include topsoil (31.00–9135.00 Ω m), weathered layer (2.35–60,801.00 Ω m), fractured basement (4.39–32,431.00 Ω m), and fresh basement (59.40–22,521.00 Ω m). About 70% of the resistivities are less than 600 Ω m indicating the possibility of a fractured formation with high potential groundwater storage. The other 30% recorded high bedrock resistivities values of possible massive crystalline granitic rock with a limited fracture. Reflection coefficient and longitudinal conductance were calculated using appropriate equations and parameters. The values of the reflection coefficient ranged from 0.215606 to 0.997049. The study revealed that 20% of the total VES points have high groundwater potential, 65% showed medium potential, 5% showed low potential, while 10% showed very low potential. The study revealed poor (20%), moderate (35%), good (30%), and very good (15%) protective capacity ratings in the area. The technique has been effective in revealing the groundwater potential and the aquifer protective capability of the area. The aquiferous zone of the Secondian formation falls within the range of 17–43 m of depth with a borehole yield of 210–240 l/m. The successful borehole in the granitic rocks shows a low yield of 10 l/m with a water-saturated zone within 20–48 m of depth.