The Experts below are selected from a list of 180 Experts worldwide ranked by ideXlab platform
Jack Dvorkin - One of the best experts on this subject based on the ideXlab platform.
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Measured and Calculated Horizontal Stresses in the Travis Peak Formation
Spe Formation Evaluation, 1994Co-Authors: Joel Walls, Jack DvorkinAbstract:This paper presents the results of an experimental program to determine in-situ horizontal Stress magnitudes from the dynamic mechanical properties of tight-gas sand cores. These measurements were made on 47 vertical plug samples from the Gas Research Institute (GRI) test wells, Staged Field Experiment (SFE) Wells 1 through 3. The wells were cored in the Travis Peak formation of east Texas from [approx]6,500 to [approx]9,500 ft deep. Vertical Overburden Stress Gradient was measured in one well using a downhole gravimeter. The core mechanical properties were used with the Anderson and Newberry equations to calculate in-situ horizontal Stress. Actual in-situ minimum horizontal Stress was determined from instantaneous shut-in pressures measured during minifracture and microfracture tests. The Newberry equation was found to give results that agreed best with measured horizontal Stress. A closer match was obtained between measured and calculated horizontal Stress values when the authors used dynamic Poisson's ratio from partially gas-saturated samples. The assumptions and limitations of the procedure are presented.
Joel Walls - One of the best experts on this subject based on the ideXlab platform.
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Measured and Calculated Horizontal Stresses in the Travis Peak Formation
Spe Formation Evaluation, 1994Co-Authors: Joel Walls, Jack DvorkinAbstract:This paper presents the results of an experimental program to determine in-situ horizontal Stress magnitudes from the dynamic mechanical properties of tight-gas sand cores. These measurements were made on 47 vertical plug samples from the Gas Research Institute (GRI) test wells, Staged Field Experiment (SFE) Wells 1 through 3. The wells were cored in the Travis Peak formation of east Texas from [approx]6,500 to [approx]9,500 ft deep. Vertical Overburden Stress Gradient was measured in one well using a downhole gravimeter. The core mechanical properties were used with the Anderson and Newberry equations to calculate in-situ horizontal Stress. Actual in-situ minimum horizontal Stress was determined from instantaneous shut-in pressures measured during minifracture and microfracture tests. The Newberry equation was found to give results that agreed best with measured horizontal Stress. A closer match was obtained between measured and calculated horizontal Stress values when the authors used dynamic Poisson's ratio from partially gas-saturated samples. The assumptions and limitations of the procedure are presented.
Scott D. Reynolds - One of the best experts on this subject based on the ideXlab platform.
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The Australian Stress map
Exploration Geophysics, 1998Co-Authors: Richard R. Hillis, Jeremy J. Meyer, Scott D. ReynoldsAbstract:The Australian Stress map project has compiled 357 quality ranked Stress orientation analyses for the Australian Continent (including New Guinea). Of these, 206 provide reliable Stress orientations, approximately doubling the number from the 1992 world Stress map compilation. Most new data are from borehole breakouts. Regionally, maximum horizontal Stress (sH) is oriented northeast-southwest from New Guinea along most of the North West Shelf, rotating to 100°N in the Carnarvon Basin. An 010°N?020°N sH orientation is observed in the Amadeus and Bowen Basins. However, in the southern half of the continent a broad east-west sH trend is observed in the Yilgarn Block, Cooper-Eromanga Basins, and from a number of isolated indicators. In the Otway and Gippsland Basins sH is oriented 130°N. The rotation of Stresses along the North West Shelf and from east-west in the Yilgarn Block to north-south in the Amadeus Basin can be explained in the context of the heterogeneous plate boundary forces acting along the convergent plate boundary to the north of Australia. However, plate boundary forces can not explain the rotation of sH from east-west in the cooper-Eromanga Basins to approximately north-south in the Amadeus Basin, which may be linked to second order influences on the Stress field. The vertical Stress (sV) Gradient in the Bonaparte and Cooper-Eromanga Basins increases with depth, and is around 20 MPa/km at 1000 m, attaining 23 MPa/km around 3 000 m. The Amadeus Basin displays an Overburden Gradient of 25 MPa/km that is little affected by depth. In situ measurements in hard rock terranes suggest a higher average Overburden Stress Gradient of 27 MPa/km. Leak-off pressures suggest that the minimum horizontal Stress (sH) is the least principal Stress (60?70% of sV) in the Bonaparte and Cooper-Eromanga Basins. Hence in'neither basin is the Stress regime one associated with reverse faulting (where sH > sh > sV). Consideration of the frictional limits to faulting suggests that, if in a state of incipient faulting, the Stress regime is approximately on the boundary between normal (sV >sh>sh) and strike-slip (sh >sV > sh) faulting environments in the Bonaparte Basin and strike-slip in the Cooper-Eromanga Basins. Applications of the Stress data include assessing both natural and induced fluid flow directions in the subsurface. For example, hydraulic fractures induced for geothermal exploitation of hot-dry-rock in the Cooper-Eromanga Basins would tend to be vertical, and not, as previously suggested horizontal.
Richard R. Hillis - One of the best experts on this subject based on the ideXlab platform.
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The Australian Stress map
Exploration Geophysics, 1998Co-Authors: Richard R. Hillis, Jeremy J. Meyer, Scott D. ReynoldsAbstract:The Australian Stress map project has compiled 357 quality ranked Stress orientation analyses for the Australian Continent (including New Guinea). Of these, 206 provide reliable Stress orientations, approximately doubling the number from the 1992 world Stress map compilation. Most new data are from borehole breakouts. Regionally, maximum horizontal Stress (sH) is oriented northeast-southwest from New Guinea along most of the North West Shelf, rotating to 100°N in the Carnarvon Basin. An 010°N?020°N sH orientation is observed in the Amadeus and Bowen Basins. However, in the southern half of the continent a broad east-west sH trend is observed in the Yilgarn Block, Cooper-Eromanga Basins, and from a number of isolated indicators. In the Otway and Gippsland Basins sH is oriented 130°N. The rotation of Stresses along the North West Shelf and from east-west in the Yilgarn Block to north-south in the Amadeus Basin can be explained in the context of the heterogeneous plate boundary forces acting along the convergent plate boundary to the north of Australia. However, plate boundary forces can not explain the rotation of sH from east-west in the cooper-Eromanga Basins to approximately north-south in the Amadeus Basin, which may be linked to second order influences on the Stress field. The vertical Stress (sV) Gradient in the Bonaparte and Cooper-Eromanga Basins increases with depth, and is around 20 MPa/km at 1000 m, attaining 23 MPa/km around 3 000 m. The Amadeus Basin displays an Overburden Gradient of 25 MPa/km that is little affected by depth. In situ measurements in hard rock terranes suggest a higher average Overburden Stress Gradient of 27 MPa/km. Leak-off pressures suggest that the minimum horizontal Stress (sH) is the least principal Stress (60?70% of sV) in the Bonaparte and Cooper-Eromanga Basins. Hence in'neither basin is the Stress regime one associated with reverse faulting (where sH > sh > sV). Consideration of the frictional limits to faulting suggests that, if in a state of incipient faulting, the Stress regime is approximately on the boundary between normal (sV >sh>sh) and strike-slip (sh >sV > sh) faulting environments in the Bonaparte Basin and strike-slip in the Cooper-Eromanga Basins. Applications of the Stress data include assessing both natural and induced fluid flow directions in the subsurface. For example, hydraulic fractures induced for geothermal exploitation of hot-dry-rock in the Cooper-Eromanga Basins would tend to be vertical, and not, as previously suggested horizontal.
Jeremy J. Meyer - One of the best experts on this subject based on the ideXlab platform.
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The Australian Stress map
Exploration Geophysics, 1998Co-Authors: Richard R. Hillis, Jeremy J. Meyer, Scott D. ReynoldsAbstract:The Australian Stress map project has compiled 357 quality ranked Stress orientation analyses for the Australian Continent (including New Guinea). Of these, 206 provide reliable Stress orientations, approximately doubling the number from the 1992 world Stress map compilation. Most new data are from borehole breakouts. Regionally, maximum horizontal Stress (sH) is oriented northeast-southwest from New Guinea along most of the North West Shelf, rotating to 100°N in the Carnarvon Basin. An 010°N?020°N sH orientation is observed in the Amadeus and Bowen Basins. However, in the southern half of the continent a broad east-west sH trend is observed in the Yilgarn Block, Cooper-Eromanga Basins, and from a number of isolated indicators. In the Otway and Gippsland Basins sH is oriented 130°N. The rotation of Stresses along the North West Shelf and from east-west in the Yilgarn Block to north-south in the Amadeus Basin can be explained in the context of the heterogeneous plate boundary forces acting along the convergent plate boundary to the north of Australia. However, plate boundary forces can not explain the rotation of sH from east-west in the cooper-Eromanga Basins to approximately north-south in the Amadeus Basin, which may be linked to second order influences on the Stress field. The vertical Stress (sV) Gradient in the Bonaparte and Cooper-Eromanga Basins increases with depth, and is around 20 MPa/km at 1000 m, attaining 23 MPa/km around 3 000 m. The Amadeus Basin displays an Overburden Gradient of 25 MPa/km that is little affected by depth. In situ measurements in hard rock terranes suggest a higher average Overburden Stress Gradient of 27 MPa/km. Leak-off pressures suggest that the minimum horizontal Stress (sH) is the least principal Stress (60?70% of sV) in the Bonaparte and Cooper-Eromanga Basins. Hence in'neither basin is the Stress regime one associated with reverse faulting (where sH > sh > sV). Consideration of the frictional limits to faulting suggests that, if in a state of incipient faulting, the Stress regime is approximately on the boundary between normal (sV >sh>sh) and strike-slip (sh >sV > sh) faulting environments in the Bonaparte Basin and strike-slip in the Cooper-Eromanga Basins. Applications of the Stress data include assessing both natural and induced fluid flow directions in the subsurface. For example, hydraulic fractures induced for geothermal exploitation of hot-dry-rock in the Cooper-Eromanga Basins would tend to be vertical, and not, as previously suggested horizontal.
