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1
Cook, Robert B. "Lazulite Graves Mountain, Lincoln County, Georgia." Rocks & Minerals 83, no. 4 (July 2008): 328–33. http://dx.doi.org/10.3200/rmin.83.4.328-333.
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Gordon, Jennings B. "A Gahnite Occurrence in Carroll County, Georgia." Rocks & Minerals 63, no. 6 (November 1988): 471–72. http://dx.doi.org/10.1080/00357529.1988.11761885.
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Cook, Robert B. "Connoisseur's Choice: Rutile, Graves Mountain, Lincoln County, Georgia." Rocks & Minerals 78, no. 2 (April 2003): 112–16. http://dx.doi.org/10.1080/00357529.2003.9926704.
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Barwood, Henry, and Robert B. Cook. "The Hogg Estate or Mineral Processing Mine, LaGrange, Troup County, Georgia." Rocks & Minerals 81, no. 3 (January 2006): 180–86. http://dx.doi.org/10.3200/rmin.81.3.180-186.
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Santamaria, Jose, and Jeff Deere. "Through the 'Scope: Baryte Microcrystals from the Cartersville Mining District, Bartow County, Georgia." Rocks & Minerals 96, no. 3 (April 26, 2021): 270–76. http://dx.doi.org/10.1080/00357529.2021.1875753.
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Wight, Georgina Deweese, and Henri D. Grissino-Mayer. "Dendrochronological Dating of an Antebellum Period House, Forsyth County, Georgia, U.S.A." Tree-Ring Research 60, no. 2 (December 2004): 91–99. http://dx.doi.org/10.3959/1536-1098-60.2.91.
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Geffner, Paul. "The Treasure Chest Pockets: An Update on the Jacksons Crossroads Amethyst Mine Wilkes County, Georgia." Rocks & Minerals 83, no. 6 (November 2008): 550–52. http://dx.doi.org/10.3200/rmin.83.6.550-552.
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Turgut, Bülent, and Merve Ateş. "Factors of soil diversity in the Batumi delta (Georgia)." Solid Earth 8, no. 1 (January 3, 2017): 1–12. http://dx.doi.org/10.5194/se-8-1-2017.
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Abstract. The aim of this study was to determine certain basic properties of soils in the Batumi delta (southwestern Georgia) to determine the relationships of studied properties and to identify differences with regards to these properties between different sampling sites in the delta that were selected based on the delta morphology. In this context, a total of 125 soil samples were collected from five different sampling sites, and the clay, silt and sand content of the samples were determined along with their mean weight diameter (MWD) values, aggregate stability (AS) values, amount of water retained under −33 (FC) and −1500 kPa (WP) pressure and organic matter (OM) content. Correlation analysis indicated that clay content and OM were positively correlated with MWD, and OM was positively correlated with AS. However, the sand content was found to be negatively correlated with MWD. In addition, clay, silt and OM content were positive correlated with FC and WP. Variance analysis results determined statistically significant differences between the sampling sites with respect to all of the evaluated properties. The active delta section of the study area was characterized by high sand content, while the lower delta plain was characterized by high OM and AS values, and the upper delta plain was characterized by high MWD values, high FC and WP moisture content levels and high clay and silt content. In conclusion, it was demonstrated that the examined properties were significantly affected by the different morphological positions and usages of these different areas. These results may help with the management of agricultural lands in the Batumi delta, which has never been studied before.
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Hower, James C., Dali Qian, Nicolas J. Briot, Madison M. Hood, and Cortland F. Eble. "Mineralogy of a rare earth element-rich Manchester coal lithotype, Clay County, Kentucky." International Journal of Coal Geology 220 (March 2020): 103413. http://dx.doi.org/10.1016/j.coal.2020.103413.
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Li, Xiao, Timothy Grey, William Vencill, James Freeman, Katilyn Price, George Cutts, and Andrew Price. "Evaluation of Cotton Responses to Fomesafen-Based Treatments Applied Preemergence." Weed Technology 32, no. 4 (May 3, 2018): 431–38. http://dx.doi.org/10.1017/wet.2018.31.
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AbstractFomesafen provides effective control of glyphosate-resistant Palmer amaranth in cotton. However, cotton seedlings can be injured when fomesafen is applied PRE. Therefore, greenhouse and field experiments were conducted at Athens, GA, and at six locations in Alabama and Georgia in 2013 and 2016 to evaluate cotton growth and yield response to fomesafen applied PRE at 70, 140, 280, 560, 1,120, or 2,240 g ai ha−1, and in combination with pendimethalin, diuron, acetochlor, and fluridone at 1×label rates. Greenhouse bioassays indicated that fomesafen reduced cotton height and dry weight with increasing rate in Cecil sandy loam and Tifton loamy sand but not in Greenville sandy clay loam––possibly as a result of this soil’s higher organic matter (OM) and clay content. Fomesafen applied at 2,240 g ai ha−1 reduced cotton stand by as much as 83% compared to the nontreated check (NTC) at all field locations except Alabama’s Macon and Baldwin counties, and 1,120 g ai ha−1 reduced cotton stand only at Pulaski County, GA, by 52%. Cotton height was reduced by the two highest rates of fomesafen at all locations except Clarke County, GA, and Baldwin County, AL. Injury data indicated more visual injury followed increasing fomesafen rates, and high-rate treatments produced more injury in sandier soils. Cotton yield was unaffected by herbicide treatments at any location, except for the 1,120 g ai ha−1 rate at Pulaski County (49% yield loss compared to NTC), 2,240 g ai ha−1 at Pulaski County (72% yield loss), and Tift County (29% yield loss). These data indicated cotton yield should not be negatively affected by fomesafen applied PRE alone within label rates or in combination with pendimethalin, diuron, acetochlor, and fluridone at 1×label rates, although some visual injury, or stand or height reduction may occur early in the growing season.
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Fallaw, W., David Snipes, and Van Price. "Wandering With William Bartram: The Section At Silver Bluff, South Carolina." Earth Sciences History 13, no. 1 (January 1, 1994): 52–57. http://dx.doi.org/10.17704/eshi.13.1.pw32124312286527.
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In his famous book, William Bartram (1791) described a stratigraphic section at Silver Bluff on the Savannah River in Aiken County, South Carolina, as dark, laminated clay containing belemnites, overlain by clays, sand, marl, and a shelly bed containing numerous oysters. There are now no known occurrences of marine megafossils in outcrops along the Savannah in Aiken County. The wording of Bartram's description of Cretaceous outcrops along the Cape Fear River in North Carolina indicates that the lower part of the Silver Bluff section was described from notes made on the Cape Fear and from his father's diary. The description of the upper beds at Silver Bluff may have been transferred from the Cape Fear, where fossiliferous Pliocene beds overlie the Cretaceous. It is probable, however, that it was from notes made at an Eocene locality in Georgia, most likely Shell Bluff on the Savannah River.
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Burley, Jon Bryan. "A vegetation productivity equation for reclaiming surface mines in Clay County, Minnesota." International Journal of Surface Mining, Reclamation and Environment 5, no. 1 (January 1991): 1–6. http://dx.doi.org/10.1080/09208119108944279.
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Hower, James C., Debora Berti, Michael F. Hochella, and Sarah M. Mardon. "Rare earth minerals in a “no tonstein” section of the Dean (Fire Clay) coal, Knox County, Kentucky." International Journal of Coal Geology 193 (June 2018): 73–86. http://dx.doi.org/10.1016/j.coal.2018.05.001.
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Sakulpitakphon, Tanaporn, James C. Hower, William H. Schram, and Colin R. Ward. "Tracking mercury from the mine to the power plant: geochemistry of the Manchester coal bed, Clay County, Kentucky." International Journal of Coal Geology 57, no. 2 (February 2004): 127–41. http://dx.doi.org/10.1016/j.coal.2003.09.004.
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Burley, J. B., and C. H. Thomsen. "Application of an agricultural soil productivity equation for reclaiming surface mines: Clay County, Minnesota." International Journal of Surface Mining, Reclamation and Environment 4, no. 3 (January 1990): 139–44. http://dx.doi.org/10.1080/09208119008944181.
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Medina, Daniel Alonso, and David Budd. "Critical Diagenetic Features Controlling Intergranular Flow Paths and Matrix Permeability in the Codell Sandstone, Northeastern Colorado." Mountain Geologist 57, no. 2 (April 1, 2020): 95–120. http://dx.doi.org/10.31582/rmag.mg.57.2.95.
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The Codell Sandstone is a hydrocarbon-bearing, tight sand (permeability <0.1 mD) that is an active target for unconventional hydrocarbon production in the Denver-Julesburg Basin. In northeastern Colorado, the intergranular microporous drainage network within this clay-rich sandstone is poorly understood, with a strong diagenetic control suggested by the lack of correlation between permeability and depositional facies. Core samples from the Wattenberg Field and Redtail areas in Weld County were used to identify which diagenetic processes were most important in developing a connected pore network. Thirteen diagenetic features were defined using thin-section petrography and electron microprobe mineralogical phase mapping, and skeletonized flow paths were delineated by epifluorescence imaging. Quartz overgrowths, mechanical compaction, and clay cements (illite, chlorite, and kaolinite) are better developed in the laminated facies than the burrowed facies. Authigenic calcite and pyrite, and dissolution of framework grains are equally developed in both types of facies. Cumulative 2D flow-path lengths positively co-vary with permeability, indicating that the skeletonized paths capture the features that control permeability. The longest flow paths in high permeability (≥0.09 mD) samples follow micropores created along the periphery of framework grains where the discontinuous quartz overgrowths abut clays. Micropores within intergranular clay masses (detrital, pore-filling cements, and authigenic replacements) associate with shorter flow paths that dominate in low permeability (≤ 0.01 mD) samples and feed the longer paths in high permeability samples. While compaction and all types of cements had a negative impact on the original pore network, the development of long contacts between quartz overgrowths and mechanically juxtaposed grains eventually became beneficial to the drainage system. The increased surface area along those contacts increased the continuity of the flow paths developed along grain surfaces. All observations indicate that the minute quartz overgrowths, and the high authigenic rugosity they created along grain boundaries, were a key diagenetic event in creating the most efficient drainage networks that now facilitate the movement of hydrocarbons at the core-plug scale.
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Doser, Diane I., Marc A. Ornelas, Isaac Martinez, Lixin Jin, Anna Ortiz, and Galen M. Kaip. "Using Geophysics to Investigate Texture and Salinity of Agricultural Soils and Their Impact on Crop Growth in El Paso County, Texas." Journal of Environmental and Engineering Geophysics 24, no. 3 (September 2019): 465–77. http://dx.doi.org/10.2113/jeeg24.3.465.
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Soil properties within the Rio Grande valley near El Paso are strongly linked to the types of fluvial deposits that serve as parent material. We used four geophysical techniques (DC resistivity, ground conductivity, capacitively coupled resistivity and magnetics) to distinguish between soil units in an alfalfa field. We combined these observations with geochemical characterization and particle size analysis in order to determine how these soils and irrigation practices influence salt buildup and water availability, and thus crop growth. Soils mapped at the site were derived from crevasse splay and flood plain deposits. Results of our investigation showed that the alfalfa grew better in soils with a 1.25 m thick unit of 40-70% sand that fined into a silty-clay (<20% sand) at greater depths. Poorer growth occurred in soils where a 0.8 m thick silty-clay (<20% sand) was underlain by a less than 2 m thick sand unit (>90% sand) we interpret as an abandoned river channel. The DC resistivity, capacitively coupled resistivity and conductivity surveys were all responsive to the major grain size changes in the upper 3 meters of soil and were able to distinguish the buried river channel. The magnetics survey was not as successful at detecting the channel, but was able to characterize near-surface grain size variability and hence distinguish between the major soil units found at the site. We believe that similar geophysical techniques could be used to rapidly evaluate soil characteristics in other regions where soils are derived from fluvial parent material.
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Matteson, A., J. P. Tomanic, M. M. Herron, D. F. Allen, and W. E. Kenyon. "NMR Relaxation of Clay/Brine Mixtures." SPE Reservoir Evaluation & Engineering 3, no. 05 (October 1, 2000): 408–13. http://dx.doi.org/10.2118/66185-pa.
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Summary Effective interpretation of nuclear magnetic resonance (NMR) logs in shaly sands requires an understanding of the NMR contribution of clays. Of particular importance is the role of clays in the rapidly relaxing part of the NMR signal. In this study we measured the transverse relaxation time spectrum T2 of brine mixed with four clays (illite, smectite, kaolinite and glauconite) as a function of compaction. The Larmor frequency was 2 MHz and the echo spacing 0.16 ms. Mild compaction was achieved by centrifuging the clay slurry at three successive pressures ranging from 1 to 125 psi. Highly compacted samples were produced in a uniaxial press at six sequential pressures ranging from 500 to 16,000 psi. Each clay/brine slurry and its associated compacted sample showed a single peak in the T2 distribution spectrum. A second peak, which could be interpreted as the "clay-bound water," was never observed. The T2 peak position shifted to faster relaxation times as compaction increased, in proportion to the pore volume-to-surface ratio, Vp/As. The single peak and Vp/As proportionality are consistent with fast diffusion between the pore water and the monolayer of water on the clay surface. Surface relaxivity varied among the four clay minerals; glauconite, the clay with the highest magnetic susceptibility and iron content had the largest surface relaxivity. These results have important implications for the interpretation of NMR logs in shaly sands. Because of the effects of compaction and to a lesser extent the iron content on a clay's T2 peak position, it is not possible to independently determine clay type from some characteristic relaxation time. These data also imply that it is not feasible to estimate the cation exchange capacity from a single time cutoff of the T2 distribution without additional information such as laboratory measurements or other log data. Introduction Nuclear magnetic resonance logging has become an important tool in evaluating a formation's petrophysical properties. The unique and valuable advantage that NMR provides is pore size distribution information. No other logging method provides these data, which are the key component of log-based estimates of capillary-bound water volume, and permeability to flow.1 It has been proposed that NMR logging can be extended to estimate clay-bound water volumes, and identify clay minerals. Clay-bound water volume, important in determining water saturation from resistivity, has been correlated with the short-T2 less than 3 ms, porosity of 45 oilfield sandstones.2 Prammer et al.'s3 NMR clay/brine study found that the T2 distribution of clay-bound water associated with kaolinite and chlorite was greater than 3 ms, for illite it ranged between 1 and 2 ms and for smectite it was less than 1 ms. Observed T2 's were then used as an indicator of cation exchange capacity (CEC) because the number of available exchange sites is proportional to a clay's specific surface area. CEC is fundamental to converting bulk resistivity measurements into water saturation. The ability to estimate clay-bound water, and to identify the clay type, from NMR T2 distributions is not compatible with the ability to determine pore size distribution from the same data. In the first two cases the molecular diffusion rate of water in the pores must be slow, whereas in the latter case it is assumed to be fast. For example, consider a monolayer of water on the surface of room-dry clay. The monolayer has a short relaxation time, less than a millisecond, because of its interaction with the solid rock. Now fill the void space between the clay particles with water and consider the two extreme cases. In the first case, there is no molecular diffusion (exchange) between the surface-monolayer water and bulk water. Thus, the T2 spectrum will contain two separate peaks, one associated with the surface-monolayer water at less than a millisecond and one associated with the bulk water. In the opposite case, molecular diffusion is highly effective, and both the surface monolayer and bulk water have a common relaxation time, a single peak in the T2 spectrum with time constant: 1 T 2 = ρ s ( A s V p ) . ( 1 ) In this equation, which provides the fundamental connection between T2 and pore size, the term ?2 is the surface relaxivity parameter that indicates the capacity of the rock to cause the decay of magnetization in the water. Fig. 1 is a conceptual drawing of a T2 distribution for a sandstone that includes fluid in small pores that are typically associated with clays, capillary-bound and producible fluid. The objective of this study was to determine whether it is possible to infer a clay-bound water volume (peak or T2 cutoff), or clay type, and a pore size distribution from a NMR distribution spectrum. To achieve this goal we designed a set of experiments that examined the NMR relaxation of clay/brine mixtures at various compaction states. In contrast to shaly sands, the clay/brine mixtures provided the means to minimize the pore volume-to-surface ratio, so that any water-monolayer-related signal might be detected. The pore volume-to-surface ratio was easily varied through compaction, and the monomineralic samples enable the NMR response of individual clay types to be evaluated. We chose to study four clays commonly found in oil-bearing sedimentary environments: kaolinite, illite, smectite and glauconite. Experimental Procedures Samples of illite and glauconite were obtained from Wards Natural Science Establishment. Kaolinite and smectite (Ca Montmorillonite) were procured from ECC Intl., Georgia Kaolin Co. and the Source Clay Minerals Repository, respectively. Various physical properties of the clays were measured. Prior to the surface area and magnetic susceptibility measurements, the clays were dried overnight in a vacuum oven at 100°C. Surface area measurements were collected using the Micromeritics Gemini 2360 with nitrogen gas as adsorbate, and magnetic susceptibilities were measured on a Johnson Matthey MSB-AUTO magnetic susceptibility balance. CEC measurements were taken using the ammonium acetate/ammonium ion-specific electrode method by David K. Davies & Assoc., Inc. Table 1 is a summary of clay type, clay origin and clay physical properties. The samples were analyzed for mineralogy using dual-range Fourier transform infrared (FTIR) spectroscopy.4 In addition, the samples were sent to X-Ray Assay Laboratories for chemical analyses (Table 2). The mineralogy data indicate the presence of quartz in the illite sample. Consequently, a <2 ?m fraction of the sample was extracted by centrifuging the illite and drying the supernatant. The physical properties for these clays are in good agreement with those in the literature.5 The clay samples used for the room-dry and clay/brine mixture NMR experiments were kept at room temperature and at typical laboratory humidity conditions of 50%. To evaluate whether clay samples have a measurable NMR signal at room-dry conditions, samples were prepared by placing the clay in a test tube and sealing it off with a stopper and Teflon tape.
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Hughes, Larry J. "Mapping contaminant-transport structures in karst bedrock with ground-penetrating radar." GEOPHYSICS 74, no. 6 (November 2009): B197—B208. http://dx.doi.org/10.1190/1.3223312.
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Ammonium perchlorate, a risk to human health, was used formerly to manufacture rocket fuel at the Naval Weapons Industrial Reserve Plant (NWIRP) McGregor, McLennon County, Texas. Perchlorate exists in several groundwater contaminant plumes, whose geometries were suspected to be influenced by transmissive bedrock structures. To identify these possible contaminant-transport pathways, a towed-array ground-penetrating radar (GPR) system was used to acquire 118 line-km of data across [Formula: see text] of the property. The shallow geology consists of bedrock limestone overlain by [Formula: see text] of clay soil. For the [Formula: see text] antennas used, the conductive clay limits depth penetration to less than [Formula: see text] and yields a [Formula: see text] wavelength, reducing lateral and vertical resolution. Nevertheless, GPR data resolved the top of bedrock in many areas. Linear discontinuities in bedrock were interpreted as weathered fracture zones, and linear areas of signal loss were attributed to deeper clay weathering along fracture zones. GPR-interpreted fractures have orientations corresponding to known lineament and fault trends, appear to control plume geometries, and tend to have higher hydraulic transmissivities. GPR results led to a more complete contaminant-transport model and were used to optimize the positions of monitoring wells needed to define the extent of contamination. This reduced the cost and time required for an environmental investigation at the site. GPR was helpful also in positioning remedial trenches across contaminated structures, resulting in plume containment at the property boundaries.
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Yang, Ping, Yi-Qun Tang, Nian-Qing Zhou, Jian-Xiu Wang, Tian-Yu She, and Xiao-Hui Zhang. "Characteristics of red clay creep in karst caves and loss leakage of soil in the karst rocky desertification area of Puding County, Guizhou, China." Environmental Earth Sciences 63, no. 3 (September 9, 2010): 543–49. http://dx.doi.org/10.1007/s12665-010-0721-1.
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Morris, T. F., and R. I. Kelly. "Origin and physical and chemical characteristics of glacial overburden in Essex and Kent counties, southwestern Ontario." Canadian Journal of Earth Sciences 34, no. 3 (March 1, 1997): 233–46. http://dx.doi.org/10.1139/e17-022.
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The overburden of Essex and Kent counties, southwestern Ontario, has been described as consisting of a clayey silt to silty clay till overlying a gravelly unit resting on bedrock. Recent Quaternary geology mapping has identified additional materials and redefined the origin of others by determining the stratigraphic position and physical and geochemical properties of materials encountered in a sonic drilling program and field mapping. Catfish Creek Till was deposited on the bedrock surface during the Nissouri Stadial as ice advanced south over the area. As ice retreated during the Erie Interstade, fine-grained glaciolacustrine material was deposited in glacial Lake Leverett and overlay Catfish Creek Till. Tavistock Till was deposited over glacial Lake Leverett material as the Huron lobe readvanced south during the Port Bruce Stadial. As the Huron lobe retreated north, coarse-grained glaciolacustrine materials were deposited in the Leamington area. Ice from the Erie lobe deposited the Port Stanley Till along the north shore of Lake Erie in Kent County and deflected meltwater southward from the Huron lobe in the Blenheim area. A series of recessional moraines were deposited by the Huron lobe as it retreated north. The area is capped by a fine-grained glaciolacustrine deposit.
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Williams, G. M., A. Stuart, and P. Coulter. "Planning and engineering in relation to waste disposal: a case study of the Alkerton landfill." Geological Society, London, Engineering Geology Special Publications 4, no. 1 (1987): 495–502. http://dx.doi.org/10.1144/gsl.eng.1987.004.01.60.
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AbstractThe integration of planning with geology and engineering is essential in the successful location and development of landfill sites, particularly in areas which are not intrinsically safe for waste disposal without engineering improvements. Although technical matters often form the primary basis for site selection, planning constraints and political factors can be as important and yet may receive less emphasis by the developers. Selection of a site can arouse concern amongst local people who consider that they will be adversely affected, despite assurances from the developer, and the formation of local action groups employing specialist expertise to oppose development of landfill sites, is now common-place. Landfill developers must therefore address technical, planning and public acceptability matters equally and effectively, in an integrated way, and must ensure that prediction of the impact of the landfill on the environment and its affect on the community proves to be accurate to maintain the credibility of the developer and the planning authorities.Recently, Oxfordshire County Council faced co-ordinated oppostion to their proposals to develop a landfill near the picturesque village of Alkerton, near Banbury. Because of the risk of pollution to nearby springs perceived by the local community, the Council created a containment site by constructing a clay trench through the vestigial ironstone, keyed into the relatively impermeable underlying silts and clays. The landfill has been operated to reduced infiltration and leachate production, and regular monitoring of environmental conditions has been carried out in conjunction with representatives from the Parish Council.This paper describes the interplay between planning, technical and political factors on which the decision to approve the development was based. The results of subsequent monitoring and the long term implications for site operations as a result of the engineering solution adopted, are also discussed.
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Glassmeyer, Michael P., and Abdul Shakoor. "Factors Contributing to Landslide Susceptibility of the Kope Formation, Cincinnati, Ohio." Environmental and Engineering Geoscience 27, no. 3 (March 11, 2021): 307–18. http://dx.doi.org/10.2113/eeg-d-20-00077.
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ABSTRACT The objective of this study was to evaluate the factors that contribute to the high frequency of landslides in the Kope Formation and the overlying colluvial soil present in the Cincinnati area, southwestern Ohio. The Kope Formation consists of approximately 80 percent shale inter-bedded with 20 percent limestone. The colluvium that forms from the weathering of the shale bedrock consists of a low-plasticity clay. Based on field observations, LiDAR data, and information gathered from city and county agencies, we created a landslide inventory map for the Cincinnati area, identifying 842 landslides. From the inventory map, we selected 10 landslides that included seven rotational and three translational slides for detailed investigations. Representative samples were collected from the landslide sites for determining natural water content, Atterberg limits, grain size distribution, shear strength parameters, and slake durability index. For the translational landslides, strength parameters were determined along the contact between the bedrock and the overlying colluvium. The results of the study indicate that multiple factors contribute to landslide susceptibility of the Kope Formation and the overlying colluvium, including low shear strength of the colluvial soil, development of porewater pressure within the slope, human activity such as loading the top or cutting the toe of a slope, low to very low durability of the bedrock that allows rapid disintegration of the bedrock and accumulation of colluvial soil, undercutting of the slope toe by stream water, and steepness of the slopes.
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Johnson, Rebecca, Mark Longman, and Brian Ruskin. "Petrographic and Petrophysical Characteristics of the Upper Devonian Three Forks Formation, Southern Nesson Anticline, North Dakota." Mountain Geologist 54, no. 3 (July 2017): 181–201. http://dx.doi.org/10.31582/rmag.mg.54.3.181.
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The Three Forks Formation, which is about 230 ft thick along the southern Nesson Anticline (McKenzie County, ND), has four “benches” with distinct petrographic and petrophysical characteristics that impact reservoir quality. These relatively clean benches are separated by slightly more illitic (higher gamma-ray) intervals that range in thickness from 10 to 20 ft. Here we compare pore sizes observed in scanning electron microscope (SEM) images of the benches to the total porosity calculated from binned precession decay times from a suite of 13 nuclear magnetic resonance (NMR) logs in the study area as well as the logarithmic mean of the relaxation decay time (T2 Log Mean) from these NMR logs. The results show that the NMR log is a valid tool for quantifying pore sizes and pore size distributions in the Three Forks Formation and that the T2 Log Mean can be correlated to a range of pore sizes within each bench of the Three Forks Formation. The first (shallowest) bench of the Three Forks is about 35 ft thick and consists of tan to green silty and shaly laminated dolomite mudstones. It has good reservoir characteristics in part because it was affected by organic acids and received the highest oil charge from the overlying lower Bakken black shale source rocks. The 13 NMR logs from the study area show that it has an average of 7.5% total porosity (compared to 8% measured core porosity), and ranges from 5% to 10%. SEM study shows that both intercrystalline pores and secondary moldic pores formed by selective partial dissolution of some grains are present. The intercrystalline pores are typically triangular and occur between euhedral dolomite rhombs that range in size from 10 to 20 microns. The dolomite crystals have distinct iron-rich (ferroan) rims. Many of the intercrystalline pores are partly filled with fibrous authigenic illite, but overall pore size typically ranges from 1 to 5 microns. As expected, the first bench has the highest oil saturations in the Three Forks Formation, averaging 50% with a range from 30% to 70%. The second bench is also about 35 ft thick and consists of silty and shaly dolomite mudstones and rip-up clast breccias with euhedral dolomite crystals that range in size from 10 to 25 microns. Its color is quite variable, ranging from green to tan to red. The reservoir quality of the second bench data set appears to change based on proximity to the Nesson anticline. In the wells off the southeast flank of the Nesson anticline, the water saturation averages 75%, ranging from 64% to 91%. On the crest of the Nesson anticline, the water saturation averages 55%, ranging from 40% to 70%. NMR porosity is consistent across the entire area of interest - averaging 7.3% and ranging from 5% to 9%. Porosity observed from samples collected on the southeast flank of the Nesson Anticline is mainly as intercrystalline pores that have been extensively filled with chlorite clay platelets. In the water saturated southeastern Nesson Anticline, this bench contains few or no secondary pores and the iron-rich rims on the dolomite crystals are less developed than those in the first bench. The chlorite platelets in the intercrystalline pores reduce average pore size to 500 to 800 nanometers. The third bench is about 55 ft thick and is the most calcareous of the Three Forks benches with 20 to 40% calcite and a proportionate reduction in dolomite content near its top. It is also quite silty and shaly with a distinct reddish color. Its dolomite crystals are 20 to 50 microns in size and partly abraded and dissolved. Ferroan dolomite rims are absent. This interval averages 7.1% porosity and ranges from 5% to 9%, but the pores average just 200 nanometers in size and occur mainly as microinterparticle pores between illite flakes in intracrystalline pores in the dolomite crystals. This interval has little or no oil saturation on the southern Nesson Anticline. Unlike other porosity tools, the NMR tool is a lithology independent measurement. The alignment of hydrogen nuclei to the applied magnetic field and the subsequent return to incoherence are described by two decay time constants, longitudinal relaxation time (T1) and transverse relaxation time (T2). T2 is essentially the rate at which hydrogen nuclei lose alignment to the external magnetic field. The logarithmic mean of T2 (T2 Log Mean) has been correlated to pore-size distribution. In this study, we show that the assumption that T2 Log Mean can be used as a proxy for pore-size distribution changes is valid in the Three Forks Formation. While the NMR total porosity from T2 remains relatively consistent in the three benches of the Three Forks, there are significant changes in the T2 Log Mean from bench to bench. There is a positive correlation between changes in T2 Log Mean and average pore size measured on SEM samples. Study of a “type” well, QEP’s Ernie 7-2-11 BHD (Sec. 11, T149N, R95W, McKenzie County), shows that the 1- to 5-micron pores in the first bench have a T2 Log Mean relaxation time of 10.2 msec, whereas the 500- to 800-nanometer pores in the chlorite-filled intercrystalline pores in the second bench have a T2 Log Mean of 4.96 msec. This compares with a T2 Log Mean of 2.86 msec in 3rd bench where pores average just 200 nanometers in size. These data suggest that the NMR log is a useful tool for quantifying average pore size in the various benches of the Three Forks Formation.
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Handoo, Z. A., A. M. Skantar, and R. P. Mulrooney. "First Report of the Sting Nematode Belonolaimus longicaudatus on Soybean in Delaware." Plant Disease 94, no. 1 (January 2010): 133. http://dx.doi.org/10.1094/pdis-94-1-0133b.
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In late July of 2005, several, large, irregular areas of severely chlorotic, stunted, and dead soybean plants were observed in two fields of soybean (Glycine max), 8.05 km apart, in sandy soil (94% sand, 2% silt, and 4% clay) in southwestern Sussex County, DE. The grower also had observed stunted corn the previous year in the same areas and thought the fields had a fertility problem. The morphology of adults and molecular analyses of the juveniles isolated from soil samples established the identity of the species as the sting nematode, Belonolaimus longicaudatus (1–4). The population density was 216 nematodes per 250 cm3 of soil. Morphological characters used for identification included female body, stylet and tail length, shape of head, stylet knobs, tail and tail terminus, number of lines in the lateral field, and vulva percentage in relation to body length. The male characters critical for identification were the following: body, stylet, spicule, and gubernaculum length; shape of head and stylet knobs; and number of lines in the lateral field. Measurements of females (n = 5) included body length (range = 2,035 to 2,120 μm, mean = 2,073.7, standard deviation [SD] = 37.0), stylet (117.0 to 127.5, 123.4, 4.5), V% (48.4 to 52.3, 50.6, 1.5), and tail (109 to 140, 120, 14.2). The lateral field had one incisure. Shape of head, stylet knobs, and tail were also consistent with B. longicaudatus. Males (n = 4) were characterized by the body length (range = 1,500 to 2,070 μm, mean = 1,753.3, SD = 290.2), stylet (117.0 to 127.5, 121.5, 5.4), spicules (41 to 50, 47, 5.2), and gubernaculum (17.0 to 18.5, 17.8, 0.8). Molecular diagnosis as B. longicaudatus was confirmed by sequencing two ribosomal DNA markers from three juveniles. Sequence of the internal transcribed spacer region ITS1 and 2 (GenBank Accession No. GQ896549) from this population was 99% identical to Florida isolate BlCi6 (DQ672368), and the 28S large ribosomal subunit D2-D3 expansion region (GQ896548) was 99% identical to Florida isolate BlCi4 (DQ672344). A high degree of similarity (>98%) was also shared by several other B. longicaudatus sequences (1). This detection represents a new state record in Delaware for B. longicaudatus. Since this detection in 2005, there have been no new reports of other observations of sting nematode or spread from these two fields tilled by the same farm operator in Delaware. Elsewhere, B. longicaudatus is known to occur in subtropical regions of the lower coastal plain, from Virginia to Florida and along the Gulf Coast into Texas. On the east coast, USDA Nematode Collection records document this nematode from Florida, Georgia, New Jersey, and South Carolina. Within Delaware, another sting nematode species, Belonolaimus maritimus, was detected on American beachgrass (Ammophila breviligulata) and bitter panicgrass (Panicum amarum var. amarulum) from Fenwick Island, near the Maryland border. Sting nematodes have also been reported in Burlington County, NJ. References: (1) U. Gozel et al. Nematropica 36:155, 2006. (2). H.-R. Han et al. Nematropica 36:37, 2006. (3) G. J. Rau. Proc. Helminthol. Soc. Wash. 25:95, 1958. (4) G. J. Rau. Proc. Helminthol. Soc. Wash. 30:119, 1963.
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Zhang, Zhenping, Xiaodong Fu, Qian Sheng, Dawei Yin, Yongqiang Zhou, and Juehao Huang. "Effect of Rainfall Pattern and Crack on the Stability of a Red Bed Slope: A Case Study in Yunnan Province." Advances in Civil Engineering 2021 (January 13, 2021): 1–21. http://dx.doi.org/10.1155/2021/6658211.
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Red bed slopes in the southwest of China are associated with a grant number of geological hazards, such as landslides, mud-rock flows, and rock blocks falling, which are vital problems in geotechnical engineering. The damage can be induced or triggered due to a series of human and environmental activities, such as excavation, concentrated or long-term rainfall, earthquake, and fluctuation of groundwater level. According to the field observations and geological exploration results, a small-scale landslide was observed on January 10, 2016, after excavation along XiaoMo highway in Yunnan Province. A numerical model in actual size using GeoStudio software based on this typical red bed engineering slope was established in this study. Back analyses and laboratory tests were used to obtain the mechanical parameters of the geomaterial inside the slope. The historic rainfall data of Mengla County from July to September in 2016 was utilized as the flux boundary in analyzing the seepage variation features and the stability of the engineering slope in the rainy season. One major tension crack was set in the shallow region of the silty clay according to the geology survey to perform the disturbance of excavation on the geomorphology of the slope. Attempts were made to establish the anisotropic permeability of the crack induced by the complex fillings, and differences in the hydraulic response between the cracking and completed slope during the rainfall process were discussed. The result shows that the factor of safety of the slope without crack before the rainfall is 1.076, and the slope is considered in the state of the critical limit equilibrium, which is in accordance with the previous state of the slope under real conditions. The pore water pressure variations of the monitor points in the shallow region of the completed slope present close compliance with the rainfall intensity subjected to different rainfall patterns, which also controls the distribution of the plastic zone in the slope after rainfall. The comparisons in the seepage field and plastic zone between the cracking and completed slope reveal that the crack can shorten the infiltration path effectively, and the higher the permeability coefficient in the vertical direction is, the larger the pore water pressure increasing zone is and the higher the underground water level is, which should be paid more attention in highway constructions.
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Grieser, William V., Robert F. Shelley, Bill J. Johnson, Eugene O. Fielder, James R. Heinze, and James R. Werline. "Data Analysis of Barnett Shale Completions." SPE Journal 13, no. 03 (September 1, 2008): 366–74. http://dx.doi.org/10.2118/100674-pa.
Full textAbstract:
Summary The north Texas Barnett shale illustrates the successful commercialization of an unconventional reservoir. However, it took 17 years to evolve from pumping crosslinked gel (XLG) carrying more than 1 million lbm of proppant per job to sand waterfracs (SWFs) consisting of large volumes of water with friction reducer and small quantities of sand. This transition to SWF stimulation opened the door for widespread development that has advanced the Newark East (Barnett shale) to the largest producing gas field in Texas. This paper investigates Barnett completion strategy from 1993 to 2002. The 393-well data set includes completion, reservoir, and production data. Unique data-evaluation tools and techniques were used to investigate various completion and reservoir parameters to determine their effects on production (Shelley and Stephenson 2000; Zangl and Hannerer 2003). We found that production results show a broad scattering when crossplotted with various completion and reservoir inputs. This result is not uncommon when analyzing field data. However, general trends were identified through comparisons of large numbers of wells. These trends were confirmed through the use of more-advanced data-mining techniques, which included self-organizing mapping (SOM) of data. The results show that SWF-type stimulation of the Barnett outperformed to varying degrees XLG treatments for the five reservoir types used in this evaluation. Geology The Barnett is a Mississippian marine shelf deposit. The Barnett shale ranges in thickness from 200 ft in the southwest region to 1,000 ft in the northeast near the Munster arch. The formation is described as a black, organic-rich (total organic content 4.5%) shale composed of fine-grained, nonsiliciclastic rocks with extremely low permeability (0.00007 to 0.005 md). The organic matter in the shale was first reported to contain 60 scf/ton but could be as high as 200 scf/ton (Montgomery et al. 2005). The Barnett is described as a "spent oil-prone source rock with porosity and permeability developed with thermal transformation of its organic matter from liquid to gas with resulting maturation-induced microfractures" (Jarvie et al. 2004). While the Barnett is classified as shale, it is complex and not homogeneous. In the core area (Denton and Wise counties), the Barnett is composed of two producing intervals notated as the upper and lower Barnett. These intervals are separated by the Forestburg lime, which varies in thickness from 20 ft to more than 150 ft. When production from the lower and upper Barnett is commingled, the lower Barnett contribution is 75-80% of the total. This value has been verified from production logs and from measuring production when isolating the intervals and producing them individually. The lower boundary (Viola/Simpson) pinches out west of the core area. The Ellenberger is a known water source, so stimulation of the lower Barnett without the Viola/Simpson can lead to high water production. Another potential for water production is the Viola, which in some areas has high water-production potential. Historical Completion Practices The first stimulation completion of the Barnett used nitrogen gas as the injection fluid. In early Barnett development, a concern about the high clay content in the shale led to precautions when using water-based fluids. An average mineral analysis from samples collected in Wise County, Texas, is given in Table 1. Early completion fluids tended to be foamed or gas-assisted. Our data set begins approximately 4 years before the first SWF was attempted. Reasons for this transition were predominately driven by economics. SWFs provided the operator with a substantial savings in stimulation costs; however, the ability to place high concentrations of proppant was eliminated. SWF began in 1997-98, and the assumption was that the Barnett would respond to a sand concentration of less than a monolayer and yield commercial production (Grieser et al. 2003). The lower Barnett was the only interval completed during the early development of the Barnett field using XLG-type treatments. The upper Barnett interval was added to the completion when the SWF era began. The addition of upper and lower net pay in the wells treated with SWF is the reason for the extra thickness. The cost savings that were realized with the evolution to the SWF enabled the additional expenditure for completing the upper Barnett. Stimulation treatment averages and production outcome are given in Table 2 for XLG fracs and SWF.
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Tomson, Mason B., Amy T. Kan, Gongmin Fu, Dong Shen, Hisham A. Nasr-El-Din, H. A. Saiari, and Musaed M. Al Thubaiti. "Mechanistic Understanding of Rock/Phosphonate Interactions and Effect of Metal Ions on Inhibitor Retention." SPE Journal 13, no. 03 (September 1, 2008): 325–36. http://dx.doi.org/10.2118/100494-pa.
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Summary This paper discusses the effects of Ca2+, Mg2+, and Fe2+ on inhibitor retention and release. Better understanding of phosphonate reactions during inhibitor squeeze treatments has direct implication on how to design and improve scale inhibitor squeeze treatments for optimum scale control. Putting various amounts of metal ions in the inhibitor pill adds another degree of freedom in squeeze design, especially in controlling return concentrations and squeeze life. Phosphonate reactions during squeeze treatments involve a series of self-regulating reactions with calcite and other minerals. However, excess calcite does not improve the retention of phosphonate due to the surface poisoning effect of Ca2+. The squeeze can be designed so that maximum squeeze life is achieved by forming a low solubility phase in the formation. Addition of Ca2+, Mg2+, and Fe2+ in the pill solution at 0.1 to 1 molar ratios significantly improves the retention of phosphonate. Alternatively, these metal ions can be dissolved from the formation while an acidic inhibitor pill is in contact with the formation minerals. Both BHPMP and DTPMP returns were significantly extended by the addition of metal ions (e.g., Ca2+ and Fe2+). The addition of Mg2+ may increase the long-term return concentration, which is important for some wells where a higher inhibitor return concentration is needed. The laboratory squeeze simulations were compared to return data obtained from squeeze treatments performed on two wells located in a sandstone reservoir in Saudi Arabia. The sandstone formation contains significant amounts of iron-bearing minerals. Introduction Mineral scale formation is a persistent problem in oil and gas production, especially in older reservoirs with increased water production and drawdown. Inhibitor squeezes are commonly used to deposit a suitable scale inhibitor in the formation. During an inhibitor squeeze treatment, a predetermined volume of the inhibitor solution is pumped into the formation and followed by injecting another volume of brine or diesel to place the inhibitor further away from the wellbore and allowing it to react with the existing rock. During production following a squeeze treatment, the inhibitor is slowly desorbed or dissolved into the formation water. Earlier efforts have focused on describing what happens and when to resqueeze (Hong and Shuler 1988; Rogers et al. 1990). More recent papers have advanced the knowledge of inhibitor reactions under various production conditions (Benton et al. 1993; Sweeney and Cooper 1993; Lawless et al. 1993; Sorbie et al. 1994; Jordan et al. 1994; Jordan et al. 1995; Jordan et al. 1997; Lawless and Smith 1998; Smith et al. 2000; Collins 2003). The primary conclusions from several previous studies (Al-Thubaiti et al. 2004; Kan et al. 2004a; Kan et al. 2004b; Tomson et al. 2006) of NTMP(aminotri(methylene phosphonic acid))-calcite reaction are:The extent of NTMP retention by carbonate-rich formation rock is limited by the amount of calcite that can dissolve prior to inhibitor-induced surface poisoning;calcite-surface poisoning effect is observed after approximately 20 molecular layers of phosphonate surface coverage that retards further calcite dissolution; andthe consequence of retarded calcite dissolution is that less basic ion, CO2-3, is released into solution, leaving the solution more acidic; therefore, more soluble calcium phosphonate solid phases form. The inhibitor return concentration can be altered by changing the inhibitor concentration in the pill. The ability to control the high inhibitor return may be useful in initial water breakthrough where high inhibitor return is desired. Kan et al. (2005) also compared the retention of NTMP, DTPMP (diethylenetriamine penta (methylene phosphonic acid)), BHPMP (bis-hexamethylenetriamine penta (methylene phosphonic acid)), and PPCA (phosphinopolycarboxylic acid) with pure calcite, a calcite-rich chalk rock, a calcite and clay-rich formation rock from Guerra Ranch, McAllen, Texas, and a quartz sandstone with very little calcite from Frio formation, Galveston County, Texas. Similar inhibitor returns were observed in both calcite-rich and low-calcite rock, suggesting that calcite is the primary solid responsible for phosphonate retention. Clays or other minerals play a secondary role in phosphonate retention. The retention of the polymer-based inhibitors is much lower than phosphonates. The data show that BHPMP provides the highest squeeze life at MIC > 50 mg/L. DTPMP is the preferred inhibitor at MIC between 1 and 50 mg/L and NTMP is the preferred inhibitor at MIC < 0.3 mg/L. Calcium ion (Ca2+) is the predominant divalent metal ion in most oilfield produced waters. Previously, several reports indicated that Ca2+ and Mg2+ have a strong effect on inhibition of barite by common inhibitors (Fernandez-Diaz et al. 1990; Boak et al. 1999; Collins 1999). Collins (1999) observed a clear change in crystal habit between barite growth in the presence and absence of Ca. Xiao et al. (2001) noted that Ca significantly enhanced the inhibitor efficiency; however, Ca had no effect on barite nucleation time in the absence of scale inhibitor. Collins (1999) reported a similar effect of Ca with polyaspartate as a barite inhibitor. The enhanced inhibition efficiency may be attributed to the reduction of net negative charge of the polyion due to complexation of the polyaspartate with divalent cations (Tomson et al. 2003). In the present paper, the influence of metal ions, e.g., Ca2+, Mg2+, and Fe2+ on the inhibitor retention and release was evaluated in both laboratory simulation and field case studies. These metal ions were either originally added to the inhibitor pill solutions or generated in-situ because of the dissolution of reservoir minerals by acidic inhibitors.
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Gregory N. Bonn, David M. Patrick. "Clay Mineral Variations in Marginal Deltaic Plain, Coastal Hancock County, Mississippi: ABSTRACT." AAPG Bulletin 71 (1987). http://dx.doi.org/10.1306/703c7f43-1707-11d7-8645000102c1865d.
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Gregory McCrae, Jesse O. Snowden. "Clay-Mineral Segregation by Differential Flocculation: Jourdan River-St. Louis Bay Estuary, Hancock County, Mississippi: ABSTRACT." AAPG Bulletin 72 (1988). http://dx.doi.org/10.1306/703c98a2-1707-11d7-8645000102c1865d.
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Steven K. Henderson. "Clay Mineralogy and Reservoir Implications Within the Pennsylvanian Cross Cut Sandstone: TWP Field, Runnels County, Texas: ABSTRACT." AAPG Bulletin 79 (1995). http://dx.doi.org/10.1306/8d2b1d04-171e-11d7-8645000102c1865d.
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Tim W. Munson. "Clay Mineralogy and Its Controls on Production, Pennsylvanian Upper Morrow Sandstone, Farnsworth Field, Ochiltree County, Texas: ABSTRACT." AAPG Bulletin 73 (1989). http://dx.doi.org/10.1306/44b4aa7d-170a-11d7-8645000102c1865d.
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Michael M. Herron, James A. Grau. "Clay and Framework Mineralogy, Cation Exchange Capacity, Matrix Density, and Porosity from Geochemical Well Logging in Kern County, California: ABSTRACT." AAPG Bulletin 71 (1987). http://dx.doi.org/10.1306/948872c6-1704-11d7-8645000102c1865d.
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