Benmadi Milad - Academia.edu (original) (raw)

Papers by Benmadi Milad

Energy & fuels, Jun 18, 2024

Interpretation, Nov 1, 2018

Understanding and predicting the impact of lithofacies changes and structural effects on fracture... more Understanding and predicting the impact of lithofacies changes and structural effects on fracture distributions is vitally important to optimize a drilling location and orientation. To evaluate and model fracture intensity of the Late Ordovician-Silurian-Early Devonian Hunton Group carbonates in Oklahoma, natural fractures were studied at different scales using borehole images, three outcrops (two horizontally bedded outcrops and one anticline outcrop), and seismic data. Natural fractures identified from eight horizontal well borehole images include conductive (open), partially open, mineralized (closed), and induced fractures. Four fracture sets were identified from borehole images and from the two horizontally bedded outcrops. A 3D fracture intensity model was populated, from the fracture intensity logs at the boreholes, and compared with a 3D lithofacies model. Principal component analysis from lithology logs produced input to a self-organizing map to classify and cluster electrofacies. Thin sections and borehole images corroborate the electrofacies around the wellbores, whereas 3D seismic data were used as constraints to build a 3D lithofacies model. A 3D lithofacies model resulted from the extrapolation of the lithofacies from the well scale to the regional seismic scale. In this study area, lithofacies and structure are interrelated and control fracture distributions. Lithofacies is the primary control, whereas structure is the secondary control. Three lithofacies (wackestone, mudstone, and mud-dominated wackestone) were identified. A positive relationship between the fracture intensity and the presence of wackestone was observed at well locations and in the mapped subsurface area. The other two lithofacies do not exhibit high fracture abundance. Structural effects influence fracture distributions near faults and positive curvature areas in the subsurface measured on the 3D seismic data. For the Hunton Anticline outcrop exposure, there was a positive linear relationship between fracture intensity and changes in curvature for the mudstone and mud-dominated wackestone and an exponential relationship for the wackestone textures. The integration of lithology and structure from multidisciplinary, multiscalar data (i.e., outcrops, image logs, and 3D seismic) helps to identify and predict the fractured zones in the Hunton carbonates and can be used for horizontal well planning as well as stimulation programs. More importantly, this study proposes a generic model to predict the variability of fractures at different scales of curvatures combined with lithology changes and can be used for other carbonate reservoirs.

Energies, Apr 1, 2020

Optimal upscaling of a high-resolution static geologic model that reflects the flow performance o... more Optimal upscaling of a high-resolution static geologic model that reflects the flow performance of the reservoir is important for reasons such as time and calculation efficiency. In this study, we demonstrate that honoring reservoir heterogeneity is critical in predicting accurate production and reducing the time and cost of running reservoir flow simulations for the Hunton Group carbonate. We integrated three-dimensional (3D) seismic data, well logs, thin sections, outcrops, multiscale fracture studies, discrete fracture networks, and geostatistical methods to create a 100 × 150 × 1 ft gridded representative geologic model. We calibrated our gridded porosity and permeability parameters, including the evaluation of fractures, by history matching the simulated production rate and cumulative production volumes from a baseline fine-scale model generated from petrophysical and production data obtained from five wells. We subsequently reperformed the simulations using a suite of coarser grids to validate our property upscaling workflow. Compared to our baseline history matching, increasing the horizontal grid cell sizes (i.e., horizontal upscaling) by factors of 2, 4, 8, and 16 results in cumulative production errors ranging from +0.5% for two time (2×) coarser to +74.22% for 16× coarser. The errors associated with vertical upscaling were significantly less, i.e., ranging from +0.5% for 2× coarser to +10.8% for 16× coarser. We observed higher production history matching errors associated with natural fracture size. Results indicate that greater connectivity provided by natural fracture length has a larger effect on production compared to the higher permeability provided by larger apertures. We also estimated the trade-off between accuracy and run times using two methods: (a) using progressively larger grid cell sizes; (b) applying 1, 5, 10, and 20 parallel processes. Computation time reduction in both scenarios may be described by simple power law equations. Observations made from our case study and upscaling workflow may be applicable to other carbonate reservoirs.

Energy in Data Conference, Austin, Texas, 20–23 February 2022

Much of the oil and gas production in Oklahoma, U.S.A., is from carbonates and shales, such as th... more Much of the oil and gas production in Oklahoma, U.S.A., is from carbonates and shales, such as the Viola Limestone, Sylvan Shale, Hunton Limestone, and Woodford Shales. Karsting is a common feature of carbonate environments, which causes topographic irregularities on an unconformity surface. In parts of the Cherokee platform (Central Oklahoma), the Hunton Limestone lies beneath the Woodford Shale and it might have controlled Woodford deposition. The study is undertaken to 1) understand the impact of karsting on the natural fractures in the Hunton Limestone, 2) study the effect of the unconformity karst surface on the overlying Woodford Shale, 3) evaluate the hardness of the Hunton Limestone and the Woodford Shale for artificial fracture stimulation, 4) determine the geomechanical properties, such as young's modulus, poisson's ratios, and brittleness index from well logs, and 5) describe the lithology and nature of the boundary contact between the Hunton Carbonate and the Woodford Shale. To accomplish this study, we used thin sections, core, outcrop, well logs, and a 3-D seismic survey data. A 3-D seismic survey and well logs were used to map the structure and thickness of the Viola Limestone, Sylvan Shale, Hunton Limestone, and the overlying Woodford Shale. The Hunton unconformity in Central Oklahoma are affected by karst features, such as collapse and sinkholes on the Hunton unconformity surface. These karst features are prominent factors controlling the paleotopography and deposition of the Woodford Shale, as was observed from 3D structural maps. Sinkhole features in 3-D structural maps range in diameter from 1150 to 2300 ft. and extend vertically to almost 300 ft. These sinkholes have a potential effect on the deposition of the overlaying Woodford Shale. Similarly, there might have been a potential effect of the Viola Limestone karstification on the overlying Sylvan Shale. The thickness variations of the Woodford Shale are controlled by paleotopography of the underlying Hunton Group where thicker Woodford is observed in the karst lows (sinkholes). Additionally, the structural maps show an inverse correlation between the thickness of limestones (Viola and Hunton) and shales (Sylvan and Woodford). We quantified the fracture intensity and apertures manually using comparator and hand lens at core site as well as using Image J software TM. Fractures in the Hunton core are affected by the karstification on the Hunton unconformity. Core data reveals that fractures exist only in the

Marine and Petroleum Geology, 2020

This is a PDF file of an article that has undergone enhancements after acceptance, such as the ad... more This is a PDF file of an article that has undergone enhancements after acceptance, such as the addition of a cover page and metadata, and formatting for readability, but it is not yet the definitive version of record. This version will undergo additional copyediting, typesetting and review before it is published in its final form, but we are providing this version to give early visibility of the article. Please note that, during the production process, errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.

Interpretation, 2018

Understanding and predicting the impact of lithofacies changes and structural effects on fracture... more Understanding and predicting the impact of lithofacies changes and structural effects on fracture distributions is vitally important to optimize a drilling location and orientation. To evaluate and model fracture intensity of the Late Ordovician-Silurian-Early Devonian Hunton Group carbonates in Oklahoma, natural fractures were studied at different scales using borehole images, three outcrops (two horizontally bedded outcrops and one anticline outcrop), and seismic data. Natural fractures identified from eight horizontal well borehole images include conductive (open), partially open, mineralized (closed), and induced fractures. Four fracture sets were identified from borehole images and from the two horizontally bedded outcrops. A 3D fracture intensity model was populated, from the fracture intensity logs at the boreholes, and compared with a 3D lithofacies model. Principal component analysis from lithology logs produced input to a self-organizing map to classify and cluster electro...

Unconventional Resources Technology Conference, Denver, Colorado, 12-14 August 2013, 2013

SPE Unconventional Resources Conference, 2014

A practical simulation model is developed and demonstrated with applications for accurate charact... more A practical simulation model is developed and demonstrated with applications for accurate characterization of production rate and pressure behavior with time in shale-gas reservoirs featuring horizontal wells intersected with multi-stages of hydraulic fractures. The model determines the contribution of each fracture stage to the overall production and predicts the pressure changes occurring in the fracture and matrix zones by a compartmental simulation approach. Various flow regimes of drawdown test are investigated for fracture diagnosis with different fracture permeability values to determine the external boundary effect. Our practical mathematical modeling, coupling the wellbore and reservoir hydraulics, is solved numerically by an iterative method to determine the flow rates coming into the horizontal well from multiple hydraulic fractures like the commingled layers intersected by a vertical well. This approach provides a reasonable description of behavior of multiple stages in ...

Journal of Sedimentary Research

Upper Devonian and Lower–Middle Mississippian strata of the North American midcontinent are ubiqu... more Upper Devonian and Lower–Middle Mississippian strata of the North American midcontinent are ubiquitously fine-grained and silt-rich, comprising both so-called shale as well as argillaceous limestone (or calcareous siltstone) that accumulated in the Laurentian epeiric sea. Although long recognized as recording marine deposition, the origin and transport of the fine-grained siliciclastic material in these units remains enigmatic because they do not connect to any proximal deltaic feeder systems. Here, we present new data on grain size, whole-rock geochemistry, mineralogy, and U-Pb detrital-zircon geochronology from units across Oklahoma; we then integrate these data with models of surface wind circulation, refined paleogeographic reconstructions, and correlations from the greater midcontinent to test the hypothesis that wind transported the siliciclastic fraction to the marine system. The exclusively very fine silt to very fine sand grain size, clear detrital origin, widespread distri...

Geological Society of America Abstracts with Programs

Highly variable porosity and lithology within Hunton Group Limestones contributes to highly heter... more Highly variable porosity and lithology within Hunton Group Limestones contributes to highly heterogeneous production. Apart from depositional circumstances, variable rock and petrophysical properties may arise from diagenetic and structural phenomena related to karsting and resulting collapse breccia. To investigate this effect, two horizontally bedded outcrops of the non-brecciated Chimneyhill Subgroup in Southern Oklahoma were studied for natural fracture orientation, aperture, and spacing. In the outcrops, three to four stratabound macrofracture (opening displacement > 0.05 mm) sets, i.e., N-S (175° azimuth), E-W (95° azimuth), NW-SE (300–320° azimuth), and NE-SW (40–70° azimuth), were identified. Fracture aperture and spacing generally exhibit a characteristic, i.e., exponential and lognormal, distribution. For comparison, we described a partly-brecciated core of the Chimneyhill Subgroup of the Hunton Group from the Pottawatomie County in Oklahoma. The core was used for petro...

Proceedings of the 7th Unconventional Resources Technology Conference, 2019

Energy & fuels, Jun 18, 2024

Interpretation, Nov 1, 2018

Understanding and predicting the impact of lithofacies changes and structural effects on fracture... more Understanding and predicting the impact of lithofacies changes and structural effects on fracture distributions is vitally important to optimize a drilling location and orientation. To evaluate and model fracture intensity of the Late Ordovician-Silurian-Early Devonian Hunton Group carbonates in Oklahoma, natural fractures were studied at different scales using borehole images, three outcrops (two horizontally bedded outcrops and one anticline outcrop), and seismic data. Natural fractures identified from eight horizontal well borehole images include conductive (open), partially open, mineralized (closed), and induced fractures. Four fracture sets were identified from borehole images and from the two horizontally bedded outcrops. A 3D fracture intensity model was populated, from the fracture intensity logs at the boreholes, and compared with a 3D lithofacies model. Principal component analysis from lithology logs produced input to a self-organizing map to classify and cluster electrofacies. Thin sections and borehole images corroborate the electrofacies around the wellbores, whereas 3D seismic data were used as constraints to build a 3D lithofacies model. A 3D lithofacies model resulted from the extrapolation of the lithofacies from the well scale to the regional seismic scale. In this study area, lithofacies and structure are interrelated and control fracture distributions. Lithofacies is the primary control, whereas structure is the secondary control. Three lithofacies (wackestone, mudstone, and mud-dominated wackestone) were identified. A positive relationship between the fracture intensity and the presence of wackestone was observed at well locations and in the mapped subsurface area. The other two lithofacies do not exhibit high fracture abundance. Structural effects influence fracture distributions near faults and positive curvature areas in the subsurface measured on the 3D seismic data. For the Hunton Anticline outcrop exposure, there was a positive linear relationship between fracture intensity and changes in curvature for the mudstone and mud-dominated wackestone and an exponential relationship for the wackestone textures. The integration of lithology and structure from multidisciplinary, multiscalar data (i.e., outcrops, image logs, and 3D seismic) helps to identify and predict the fractured zones in the Hunton carbonates and can be used for horizontal well planning as well as stimulation programs. More importantly, this study proposes a generic model to predict the variability of fractures at different scales of curvatures combined with lithology changes and can be used for other carbonate reservoirs.

Energies, Apr 1, 2020

Optimal upscaling of a high-resolution static geologic model that reflects the flow performance o... more Optimal upscaling of a high-resolution static geologic model that reflects the flow performance of the reservoir is important for reasons such as time and calculation efficiency. In this study, we demonstrate that honoring reservoir heterogeneity is critical in predicting accurate production and reducing the time and cost of running reservoir flow simulations for the Hunton Group carbonate. We integrated three-dimensional (3D) seismic data, well logs, thin sections, outcrops, multiscale fracture studies, discrete fracture networks, and geostatistical methods to create a 100 × 150 × 1 ft gridded representative geologic model. We calibrated our gridded porosity and permeability parameters, including the evaluation of fractures, by history matching the simulated production rate and cumulative production volumes from a baseline fine-scale model generated from petrophysical and production data obtained from five wells. We subsequently reperformed the simulations using a suite of coarser grids to validate our property upscaling workflow. Compared to our baseline history matching, increasing the horizontal grid cell sizes (i.e., horizontal upscaling) by factors of 2, 4, 8, and 16 results in cumulative production errors ranging from +0.5% for two time (2×) coarser to +74.22% for 16× coarser. The errors associated with vertical upscaling were significantly less, i.e., ranging from +0.5% for 2× coarser to +10.8% for 16× coarser. We observed higher production history matching errors associated with natural fracture size. Results indicate that greater connectivity provided by natural fracture length has a larger effect on production compared to the higher permeability provided by larger apertures. We also estimated the trade-off between accuracy and run times using two methods: (a) using progressively larger grid cell sizes; (b) applying 1, 5, 10, and 20 parallel processes. Computation time reduction in both scenarios may be described by simple power law equations. Observations made from our case study and upscaling workflow may be applicable to other carbonate reservoirs.

Energy in Data Conference, Austin, Texas, 20–23 February 2022

Much of the oil and gas production in Oklahoma, U.S.A., is from carbonates and shales, such as th... more Much of the oil and gas production in Oklahoma, U.S.A., is from carbonates and shales, such as the Viola Limestone, Sylvan Shale, Hunton Limestone, and Woodford Shales. Karsting is a common feature of carbonate environments, which causes topographic irregularities on an unconformity surface. In parts of the Cherokee platform (Central Oklahoma), the Hunton Limestone lies beneath the Woodford Shale and it might have controlled Woodford deposition. The study is undertaken to 1) understand the impact of karsting on the natural fractures in the Hunton Limestone, 2) study the effect of the unconformity karst surface on the overlying Woodford Shale, 3) evaluate the hardness of the Hunton Limestone and the Woodford Shale for artificial fracture stimulation, 4) determine the geomechanical properties, such as young's modulus, poisson's ratios, and brittleness index from well logs, and 5) describe the lithology and nature of the boundary contact between the Hunton Carbonate and the Woodford Shale. To accomplish this study, we used thin sections, core, outcrop, well logs, and a 3-D seismic survey data. A 3-D seismic survey and well logs were used to map the structure and thickness of the Viola Limestone, Sylvan Shale, Hunton Limestone, and the overlying Woodford Shale. The Hunton unconformity in Central Oklahoma are affected by karst features, such as collapse and sinkholes on the Hunton unconformity surface. These karst features are prominent factors controlling the paleotopography and deposition of the Woodford Shale, as was observed from 3D structural maps. Sinkhole features in 3-D structural maps range in diameter from 1150 to 2300 ft. and extend vertically to almost 300 ft. These sinkholes have a potential effect on the deposition of the overlaying Woodford Shale. Similarly, there might have been a potential effect of the Viola Limestone karstification on the overlying Sylvan Shale. The thickness variations of the Woodford Shale are controlled by paleotopography of the underlying Hunton Group where thicker Woodford is observed in the karst lows (sinkholes). Additionally, the structural maps show an inverse correlation between the thickness of limestones (Viola and Hunton) and shales (Sylvan and Woodford). We quantified the fracture intensity and apertures manually using comparator and hand lens at core site as well as using Image J software TM. Fractures in the Hunton core are affected by the karstification on the Hunton unconformity. Core data reveals that fractures exist only in the

Marine and Petroleum Geology, 2020

This is a PDF file of an article that has undergone enhancements after acceptance, such as the ad... more This is a PDF file of an article that has undergone enhancements after acceptance, such as the addition of a cover page and metadata, and formatting for readability, but it is not yet the definitive version of record. This version will undergo additional copyediting, typesetting and review before it is published in its final form, but we are providing this version to give early visibility of the article. Please note that, during the production process, errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.

Interpretation, 2018

Understanding and predicting the impact of lithofacies changes and structural effects on fracture... more Understanding and predicting the impact of lithofacies changes and structural effects on fracture distributions is vitally important to optimize a drilling location and orientation. To evaluate and model fracture intensity of the Late Ordovician-Silurian-Early Devonian Hunton Group carbonates in Oklahoma, natural fractures were studied at different scales using borehole images, three outcrops (two horizontally bedded outcrops and one anticline outcrop), and seismic data. Natural fractures identified from eight horizontal well borehole images include conductive (open), partially open, mineralized (closed), and induced fractures. Four fracture sets were identified from borehole images and from the two horizontally bedded outcrops. A 3D fracture intensity model was populated, from the fracture intensity logs at the boreholes, and compared with a 3D lithofacies model. Principal component analysis from lithology logs produced input to a self-organizing map to classify and cluster electro...

Unconventional Resources Technology Conference, Denver, Colorado, 12-14 August 2013, 2013

SPE Unconventional Resources Conference, 2014

A practical simulation model is developed and demonstrated with applications for accurate charact... more A practical simulation model is developed and demonstrated with applications for accurate characterization of production rate and pressure behavior with time in shale-gas reservoirs featuring horizontal wells intersected with multi-stages of hydraulic fractures. The model determines the contribution of each fracture stage to the overall production and predicts the pressure changes occurring in the fracture and matrix zones by a compartmental simulation approach. Various flow regimes of drawdown test are investigated for fracture diagnosis with different fracture permeability values to determine the external boundary effect. Our practical mathematical modeling, coupling the wellbore and reservoir hydraulics, is solved numerically by an iterative method to determine the flow rates coming into the horizontal well from multiple hydraulic fractures like the commingled layers intersected by a vertical well. This approach provides a reasonable description of behavior of multiple stages in ...

Journal of Sedimentary Research

Upper Devonian and Lower–Middle Mississippian strata of the North American midcontinent are ubiqu... more Upper Devonian and Lower–Middle Mississippian strata of the North American midcontinent are ubiquitously fine-grained and silt-rich, comprising both so-called shale as well as argillaceous limestone (or calcareous siltstone) that accumulated in the Laurentian epeiric sea. Although long recognized as recording marine deposition, the origin and transport of the fine-grained siliciclastic material in these units remains enigmatic because they do not connect to any proximal deltaic feeder systems. Here, we present new data on grain size, whole-rock geochemistry, mineralogy, and U-Pb detrital-zircon geochronology from units across Oklahoma; we then integrate these data with models of surface wind circulation, refined paleogeographic reconstructions, and correlations from the greater midcontinent to test the hypothesis that wind transported the siliciclastic fraction to the marine system. The exclusively very fine silt to very fine sand grain size, clear detrital origin, widespread distri...

Geological Society of America Abstracts with Programs

Highly variable porosity and lithology within Hunton Group Limestones contributes to highly heter... more Highly variable porosity and lithology within Hunton Group Limestones contributes to highly heterogeneous production. Apart from depositional circumstances, variable rock and petrophysical properties may arise from diagenetic and structural phenomena related to karsting and resulting collapse breccia. To investigate this effect, two horizontally bedded outcrops of the non-brecciated Chimneyhill Subgroup in Southern Oklahoma were studied for natural fracture orientation, aperture, and spacing. In the outcrops, three to four stratabound macrofracture (opening displacement > 0.05 mm) sets, i.e., N-S (175° azimuth), E-W (95° azimuth), NW-SE (300–320° azimuth), and NE-SW (40–70° azimuth), were identified. Fracture aperture and spacing generally exhibit a characteristic, i.e., exponential and lognormal, distribution. For comparison, we described a partly-brecciated core of the Chimneyhill Subgroup of the Hunton Group from the Pottawatomie County in Oklahoma. The core was used for petro...

Proceedings of the 7th Unconventional Resources Technology Conference, 2019

Much of the oil and gas production in Oklahoma, U.S.A., is from carbonates and shales, such as th... more Much of the oil and gas production in Oklahoma, U.S.A., is from carbonates and shales, such as the Viola Limestone, Sylvan Shale, Hunton Limestone, and Woodford Shales. Karsting is a common feature of carbonate environments, which causes topographic irregularities on an unconformity surface. In parts of the Cherokee platform (Central Oklahoma), the Hunton Limestone lies beneath the Woodford Shale and it might have controlled Woodford deposition. The study is undertaken to 1) understand the impact of karsting on the natural fractures in the Hunton Limestone, 2) study the effect of the unconformity karst surface on the overlying Woodford Shale, 3) evaluate the hardness of the Hunton Limestone and the Woodford Shale for artificial fracture stimulation, 4) determine the geomechanical properties, such as young's modulus, poisson's ratios, and brittleness index from well logs, and 5) describe the lithology and nature of the boundary contact between the Hunton Carbonate and the Woodford Shale. To accomplish this study, we used thin sections, core, outcrop, well logs, and a 3-D seismic survey data. A 3-D seismic survey and well logs were used to map the structure and thickness of the Viola Limestone, Sylvan Shale, Hunton Limestone, and the overlying Woodford Shale. The Hunton unconformity in Central Oklahoma are affected by karst features, such as collapse and sinkholes on the Hunton unconformity surface. These karst features are prominent factors controlling the paleotopography and deposition of the Woodford Shale, as was observed from 3D structural maps. Sinkhole features in 3-D structural maps range in diameter from 1150 to 2300 ft. and extend vertically to almost 300 ft. These sinkholes have a potential effect on the deposition of the overlaying Woodford Shale. Similarly, there might have been a potential effect of the Viola Limestone karstification on the overlying Sylvan Shale. The thickness variations of the Woodford Shale are controlled by paleotopography of the underlying Hunton Group where thicker Woodford is observed in the karst lows (sinkholes). Additionally, the structural maps show an inverse correlation between the thickness of limestones (Viola and Hunton) and shales (Sylvan and Woodford). We quantified the fracture intensity and apertures manually using comparator and hand lens at core site as well as using Image J software TM. Fractures in the Hunton core are affected by the karstification on the Hunton unconformity. Core data reveals that fractures exist only in the

Karsting is a common feature of carbonate environments that causes topographic irregularities on ... more Karsting is a common feature of carbonate environments that causes topographic irregularities on an unconformity surface. In parts of the Cherokee platform, Central Oklahoma, the Hunton Limestone underlies the Woodford Shale and might have controlled Woodford deposition. The main objectives of this study are to 1) understand the impact of karsting on the natural fractures in the Hunton Limestone 2) study the effect of the unconformity karst surface on the overlying Woodford Shale, and 3) evaluate the hardness of the Hunton Limestone and the Woodford Shale for artificial fracture stimulation. To achieve this understanding, we used a 3D seismic survey and well logs to map the structure and thickness of the Viola Limestone, Sylvan Shale, Hunton Limestone, and the overlying Woodford Shale. In addition, we used core analyses to quantify the fracture aperture and intensity, measure the hardness using a Rebound Hammer TM , and describe the lithology and nature of the boundary contact. The karst features, such as collapse and sinkholes on the Hunton unconformity surface are prominent factors controlling the paleotopography and deposition of the Woodford Shale, as was observed from 3D structural maps. Similarly, there might be a potential effect of the Viola Limestone karstification on the overlying Sylvan Shale. The thickness variations of the Woodford Shale are controlled by paleotopography of the underlying Hunton Group, where thicker Woodford is observed in the karst lows (sinkholes) (Infante et al, in press). Sinkhole features range in diameter from 1150 to 2300 ft. and extend vertically to almost 300 ft. Additionally, there is an inverse correlation between the thickness of limestones (Viola and Hunton) and shales (Sylvan and Woodford). Core data reveals that fractures exist only in the karstified section of the uppermost 15 ft. of the Hunton due to karstification. The fracture aperture (sealed) ranges from 0.003 to 0.01 in. and the fracture intensity ranges from 8 to 30 fractures/ ft. every 6 inches (on average) along the core length. The higher hardness measurements correspond to areas with higher fracture abundance due to more brittle rocks in the karsted zone. An erosional unconformity surface between the Hunton Limestone and the overlying Woodford shale, with possibly some Misener Sandstone occurs in one core. This study predicts the locations of thick Woodford Shale sections suggesting possible spots for landing horizontal wells in the Woodford Shale.