EP0169076A2
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Method of surveying the earth's subsurface formations
Assignee: BP Corp North America Inc
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Filing: 1985-07-19
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Granted: —
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Expires: 2005-07-19
Abstract
Abstract Polarized shear wave surveys are performed to determine azimuthal variations in the earth's subsurface caused by fracture orientation and density. The surveys may be done by using the same polarization (either horizontal or vertical) shear waves along two different seismic lines of profile, or by using different polarization shear waves along one common line of profile. The survey data are then processed and compared; any differences constitute a measure of fracture orientation and density. Subsurface zones of high fracture density, once identified, have been found to afford a higher likelihood of successful well completion.
Inventors
- 👤 Richard Martin Alford
- 👤 Heloise Bloxson Lynn
- 👤 Leon Arthur Thomsen
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-05 06:33
CPC Classifications
G; G01; G01V; G01V1/00; G01V1/28; G01V1/284; G01V2210/00; G01V2210/60; G01V2210/62; G01V2210/626
Claims Analysis
Total Claims: 31
Claim 1
Independent Claim
101 words
A method of surveying the earth's subsurface formations comprising the steps of: (a) imparting into the earth shear wave seismic energy polarized in a first direction along a first seismic line of profile; (b) recording the reflected shear wave seismic energy with a first geophone having a matched polarization to produce a first shear wave record; (c) imparting into the earth shear wave seismic energy polarized in a second direction along a second seismic line of profile; and (d) recording the reflected shear wave seismic energy with a second geophone having a matched polarization to produce a second shear wave record.
Claim 2
Independent Claim
101 words
A method of surveying the earth's subsurface formations comprising the steps of: (a) imparting into the earth shear wave seismic energy polarized in a first direction along a first seismic line of profile; (b) recording the reflected shear wave seismic energy with a first geophone having a matched polarization to produce a first shear wave record; (c) imparting into the earth shear wave seismic energy polarized in a second direction along a second seismic line of profile; and (d) recording the reflected shear wave seismic energy with a second geophone having a matched polarization to produce a second shear wave record.
Claim 3
Dependent Claim
47 words
The method of Claim 1, further including the steps of: (a) processing the first and second shear wave records to produce a first and second shear wave section; and (b) comparing the first and second shear wave seismic sections to determine azimuthal variations in the earth's subsurface.
Claim 4
Dependent Claim
50 words
The method of Claim 1 or Claim 2 further including the steps of: (a) imparting into the earth shear wave seismic energy polarized perpendicular to the first seismic line of profile; and (b) imparting into the earth shear wave seismic energy polarized perpendicular to the second seismic line of profile.
Claim 5
Dependent Claim
50 words
The method of Claim 1 or Claim 2, further including the steps of: (a) imparting into the earth shear wave seismic energy polarized parallel to the first seismic line of profile; and (b) imparting into the earth shear wave seismic energy polarized parallel to the second seismic line of profile.
Claim 6
Independent Claim
19 words
The method of any one of the preceding claims, wherein the first and second seismic lines of profile cross.
Claim 7
Dependent Claim
17 words
The method of Claim 5, wherein the first and second seismic lines of profile are substantially orthogonal.
Claim 8
Independent Claim
22 words
The method of any one of Claims 1 to 4 wherein the first and second seismic lines of profile are substantially collinear.
Claim 9
Dependent Claim
16 words
The method of Claim 7 wherein the first and second seismic lines of profile are coincident.
Claim 10
Dependent Claim
20 words
The method of Claim 7 or Claim 8 wherein the first and second shear wave seismic energy polarizations are orthogonal.
Claim 11
Dependent Claim
26 words
The method of Claim 9 wherein the first and second shear wave seismic energy polarizations are mutually orthogonal with respect to the seismic lines of profile.
Claim 12
Independent Claim
69 words
The method of any one of the preceding claims wherein each step of imparting into the earth shear wave seismic energy comprises the step of imparting shear wave seismic energy at selected points along the associated seismic line of profile and wherein each step of recording reflected shear wave energy comprises the step of recording reflected shear wave energy at selected points on the associated seismic line of profile.
Claim 13
Independent Claim
29 words
The method of any one of the preceding claims, further including the step of conducting a compressional wave seismic survey along the first and second seismic lines of profile.
Claim 14
Dependent Claim
129 words
The method of Claim 12 wherein the step of conducting a compressional wave seismic survey comprises the steps of: (a) imparting compressional wave seismic energy at selected points along the first seismic line of profile into the earth; (b) recording the response of the earth formations to the compressional wave seismic energy at selected points on the first seismic line of profile; (c) imparting compressional wave seismic energy at selected points along the second seismic line of profile into the earth; (d) recording the response of the earth formations to the compressional wave seismic energy at selected points on the second seismic line of profile; and (e) processing the recorded responses to form a compressional wave seismic section for each of the first and second seismic lines of profile.
Claim 15
Dependent Claim
24 words
The method of Claim 13 wherein the step of processing both recorded responses includes determining the presence of fractures and their orientation and density.
Claim 16
Independent Claim
26 words
The method of any one of Claims 2 to 14 further comprising the step of determining fracture density from the azimuthal variations in the earth's subsurface.
Claim 17
Independent Claim
56 words
The method of any one of Claims 2 to 15 wherein: (a) said step of processing the first and second shear wave records includes determining the arrival times of the shear waves; and (b) said step of comparing the first and second seismic sections includes determining difference in arrival times in the two shear wave sections.
Claim 18
Independent Claim
58 words
The method of any one of Claims 2 to 16 wherein: (a) said step of processing the first and second shear wave records includes determining reflection amplitudes for events in the shear wave sections; (b) said step of comparing the first and second seismic sections includes comparing reflection amplitudes for corresponding events in the two shear wave sections.
Claim 19
Independent Claim
24 words
The method of any one of the preceding claims, further including the step of locating regions of oriented fractures within the earth's subsurface formations.
Claim 20
Dependent Claim
27 words
The method of Claim 18 further including the step of locating one of the seismic lines of profile substantially parallel to the orientation of the oriented fractures.
Claim 21
Dependent Claim
27 words
The method of Claim 18 further including the step of locating one of the seismic lines of profile substantially perpendicular to the orientation of the oriented fractures.
Claim 22
Independent Claim
30 words
The method of any one of Claims 18 to 20 further comprising the step of arranging for distinct seismic lines of profile to intersect in the region of oriented fractures.
Claim 23
Independent Claim
29 words
The method of any one of Claims 2 to 21 wherein the processing step includes determining the presence of fractures and their orientation and density in the subsurface formations.
Claim 24
Independent Claim
165 words
A method of surveying subsurface earth formations along two crossing seismic lines to investigate for fractures and their orientations and density in subsurface formations, comprising the steps of: (a) imparting compressional wave seismic energy at selected points along the first seismic line of profile into the earth; (b) recording the response of the earth's formations to the compressional wave seismic energy at selected points on the first seismic line of profile; (c) imparting compressional wave seismic energy at selected points along the second seismic line of profile into the earth; (d) recording the response of the earth's formations to the compressional wave seismic energy at selected points on the second seismic line of profile; (e) processing the recorded responses to form a compressional wave seismic section for each of the first and second seismic lines of profile; and (f) comparing the recorded responses of both the first and second lines of profile at large angles of incidence to determine azimuthal differences attributable to oriented fractures.
Claim 25
Independent Claim
165 words
A method of surveying subsurface earth formations along two crossing seismic lines to investigate for fractures and their orientations and density in subsurface formations, comprising the steps of: (a) imparting compressional wave seismic energy at selected points along the first seismic line of profile into the earth; (b) recording the response of the earth's formations to the compressional wave seismic energy at selected points on the first seismic line of profile; (c) imparting compressional wave seismic energy at selected points along the second seismic line of profile into the earth; (d) recording the response of the earth's formations to the compressional wave seismic energy at selected points on the second seismic line of profile; (e) processing the recorded responses to form a compressional wave seismic section for each of the first and second seismic lines of profile; and (f) comparing the recorded responses of both the first and second lines of profile at large angles of incidence to determine azimuthal differences attributable to oriented fractures.
Claim 26
Dependent Claim
17 words
The method of Claim 23 wherein the first and second seismic lines of profile are substantially orthogonal.
Claim 27
Dependent Claim
26 words
The method of Claim 23 or Claim 24 wherein one of the seismic lines of profile is substantially perpendicular to the suspected orientation of the fractures.
Claim 28
Dependent Claim
26 words
The method of Claim 23 or Claim 24 wherein one of the seismic lines of profile is substantially parallel to the suspected orientation of the fractures.
Claim 29
Independent Claim
119 words
A method for determining azimuthal variations in the earth's subsurface comprising the steps of: (a) displaying a first record of shear wave seismic energy imparted into the earth by a shear wave seismic source polarized in a first direction along a first seismic line of profile and received by a first geophone having a matched polarization; (b) displaying a second record of shear wave seismic energy imparted into the earth by a shear wave seismic source polarized in a second direction along a second seismic line of profile and received by a second geophone having a matched polarization; and (c) comparing the first and second record of shear wave seismic energy to determine azimuthal variations in the earth's subsurface.
Claim 30
Independent Claim
119 words
A method for determining azimuthal variations in the earth's subsurface comprising the steps of: (a) displaying a first record of shear wave seismic energy imparted into the earth by a shear wave seismic source polarized in a first direction along a first seismic line of profile and received by a first geophone having a matched polarization; (b) displaying a second record of shear wave seismic energy imparted into the earth by a shear wave seismic source polarized in a second direction along a second seismic line of profile and received by a second geophone having a matched polarization; and (c) comparing the first and second record of shear wave seismic energy to determine azimuthal variations in the earth's subsurface.
Claim 31
Dependent Claim
16 words
The method of Claim 27 wherein the first and second seismic lines of profile are coincident.
References Cited (Backward Citations)
No citation records indexed.
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