Patent EA-004261-B1 (EA)
Title: Method for detecting direction and relative magnitude of maximum horizontal stress in earth's crust
Inventor: DAVIDSON JOHN KENNETH
IPC: G01V11/00
Filed: 2001-05-18
Abstract: 1. A method of determining the direction of the maximum horizontal stress (SH) at a horizon within a prospect including the following steps: a) obtaining a plurality of seismic reflection lines within the prospect; b) selecting at least two seismic reflection lines which cross the prospect substantially in the direction of maximum dip; c) selecting at least one further seismic line which lies along a longitudinal axis of the prospect; d) identifying on the selected seismic lines at least one substantially vertical crust cutting fault; e) identifying on the selected seismic lines a plurality of horizons; f) determining and assigning the plurality of horizons with geological ages; g) identifying on the selected seismic lines at least one horizon produced during a compressional pulse period; h) selecting at least one horizon from step g which is cut by at least one of the identified crust cutting faults, i) mapping in plan the crust cutting fault at the horizon selected in step h, j) identifying at least one anticline within the horizon identified in step i, k) mapping in plan the anticline at the horizon identified in step j, l) selecting at least one mapped anticline which in plan view extends substantially parallel to the adjacent crust cutting faults mapped in step i; wherein SH is substantially perpendicular to the selected anticlines in that horizon. 2. A method of determining the direction of the maximum horizontal stress (SH) at a horizon within a prospect including the following steps: a) obtaining a plurality of seismic reflection lines within the prospect; b) selecting at least two seismic reflection lines which cross the prospect substantially in the direction of maximum dip; c) selecting at least one further seismic line which lies along a longitudinal axis of the prospect; d) identifying on the selected seismic lines at least one substantially vertical crust cutting fault; e) identifying on the selected seismic lines a plurality of horizons; f) determining and assigning the plurality of horizons with geological ages; g) identifying on the selected seismic lines at least one horizon produced during a compressional pulse period; h) selecting at least one horizon from step g which is cut by at least one of the identified crust cutting faults, i) mapping in plan the crust cutting fault at the horizon selected in step h, j) identifying at least one syncline within the horizon identified in step i, k) mapping in plan the syncline at the horizon identified in step j, l) selecting at least one mapped syncline which in plan view extends substantially parallel to the adjacent crust cutting faults mapped in step i; wherein SH is substantially perpendicular to the selected syncline in that horizon. 3. A method of determining the direction of the maximum horizontal stress (SH) at a horizon within a prospect including the following steps: a) obtaining a plurality of seismic reflection lines within the prospect; b) selecting at least two seismic reflection lines which cross the prospect substantially in the direction of maximum dip; c) selecting at least one further seismic line which lies along a longitudinal axis of the prospect; d) identifying on the selected seismic lines at least one substantially vertical crust cutting fault; e) identifying on the selected seismic lines a plurality of horizons; f) determining and assigning the plurality of horizons with geological ages; g) identifying on the selected seismic lines at least one horizon produced during a compressional pulse period; h) selecting at least one horizon from step g which is cut by at least one of the identified crust cutting faults, i) mapping in plan the crust cutting fault at the horizon selected in step h, j) identifying at least one reverse fault within the horizon identified in step i, k) mapping in plan the reverse fault at the horizon identified in step j, l) selecting at least one mapped reverse fault which in plan view extends substantially parallel to the adjacent crust cutting faults mapped in step i; wherein SH is substantially perpendicular to the selected reverse fault in that horizon. 4. A method of determining the direction of the maximum horizontal stress (SH) at a horizon within a prospect including the following steps: a) obtaining a plurality of seismic reflection lines within the prospect; b) selecting at least two seismic reflection lines which cross the prospect substantially in the direction of maximum dip; c) selecting at least one further seismic line which lies along a longitudinal axis of the prospect; d) identifying on the selected seismic lines at least one substantially vertical crust cutting fault; e) identifying on the selected seismic lines a plurality of horizons; f) determining and assigning the plurality of horizons with geological ages; g) identifying on the selected seismic lines at least one horizon produced during a compressional pulse period; h) selecting at least one horizon from step g which is cut by at least one of the identified crust cutting faults, i) mapping in plan the crust cutting fault at the horizon selected in step h, j) identifying at least one non crust cutting normal fault within the horizon identified in step i, k) mapping in plan the non crust cutting normal fault at the horizon identified in step j, l) selecting at least one mapped non crust cutting normal fault which in plan view extends substantially perpendicular to the adjacent crust cutting faults mapped in step i; wherein SH is substantially parallel to the selected non crust cutting normal faults in that horizon. 5. A method of determining the direction of the maximum horizontal stress (SH) at a horizon within a prospect including the following steps: a) obtaining a plurality of seismic reflection lines within the prospect; b) selecting at least two seismic reflection lines which cross the prospect substantially in the direction of maximum dip; c) selecting at least one further seismic line which lies along a longitudinal axis of the prospect; d) identifying on the selected seismic lines at least one substantially vertical crust cutting fault; e) identifying on the selected seismic lines a plurality of horizons; f) determining and assigning the plurality of horizons with geological ages; g) identifying on the selected seismic lines at least one horizon produced during a compressional pulse period; h) selecting at least one horizon from step g which is cut by at least one of the identified crust cutting faults, i) mapping in plan the crust cutting fault at the horizon selected in step h, j) identifying at least one non crust cutting strike slip fault with a right or dextral sense of offset and a second non crust cutting strike slip fault with a left or sinistral sense of offset within the horizon steps, k) mapping in plan the non crust cutting strike slip faults at the horizon identified in step j, l) selecting those mapped non crust cutting strike slip faults which in plan view extend substantially perpendicularly to the adjacent crust cutting faults mapped in step l; wherein SH is substantially parallel with the opposing approaching sectors formed by the selected dextral and sinistral non crust cutting strike slip faults in that horizon. 6. A method according to any one of claims 2 to 5 including: m1) identifying at least one anticline within the horizon identified in step i, n1) mapping in plan the anticline at the horizon identified in step m1, o1) selecting at least one mapped anticline which in plan view extends substantially parallel to the adjacent crust cutting faults mapped in step i; wherein SH is substantially perpendicular to the selected anticlines in that horizon. 7. A method according to any one of claims 1, or 3 to 6 including: m2) identifying at least one syncline within the horizon identified in step i, n2) mapping in plan the syncline at the horizon identified in step m2, o2) selecting at least one mapped syncline which in plan view extends substantially parallel to the adjacent crust cutting faults mapped in step i; wherein SH is substantially perpendicular to the selected syncline in that horizon. 8. A method according to any one of claims 1, 2 or 4 to 7 including: m3) identifying at least one reverse fault within the horizon identified in step i, n3) mapping in plan the reverse fault at the horizon identified in step m3, o3) selecting at least one mapped reverse fault which in plan view extends substantially parallel to the adjacent crust cutting faults mapped in step i; wherein SH is substantially perpendicular to the selected reverse fault in that horizon. 9. A method according to any one of claims 1 to 3, or 5 to 8 including: m4) identifying at least one non crust cutting normal fault within the horizon identified in step i, n4) mapping in plan the non crust cutting normal fault at the horizon identified in step m4, o4) selecting at least one mapped non crust cutting normal fault which in plan view extends substantially perpendicular to the adjacent crust cutting faults mapped in step i; wherein SH is substantially parallel to the selected non crust cutting normal faults in that horizon. 10. A method according to any one of claims 1 to 4 or 6 to 9 including: m5) identifying at least one non crust cutting strike slip fault with a right or dextral sense of offset and a second non crust cutting strike slip fault with a left or sinistral sense of offset within the horizon identified in step l, n5) mapping in plan the strike slip faults at the horizon identified in step m5, o5) selecting those mapped strike slip faults which in plan view extend substantially perpendicularly to the adjacent crust cutting faults mapped in step i, wherein SH is substantially parallel with the opposing approaching sectors formed by the selected dextral and sinistral non crust cutting strike slip faults in that horizon. 11. A method according to any one of the preceding claims including: p1) repeating step g for at least one differ