US4432078A
Expired / Lapsed
US
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Method and apparatus for fracturing a deep borehole and determining the fracture azimuth
Assignee: Western Atlas International Inc
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Filing: 1981-01-21
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Granted: 1984-02-14
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Expires: 2001-01-21
Abstract
Abstract A method of fracturing a deep borehole to form a vertical fracture, and of determining the azimuth of the resulting fracture, comprising pumping a pressurized fracture fluid into said well through a pipe from the surface, to provide a bottom hole pressure P which is less than the normal fracturing press (NFP), and generating a series of sharp pressure pulses (SPP) of selected magnitude, such that when added to the pressure P, provide pressure peaks greater than the NFP. By providing arrays of seismic sensors at the surface and determining the direction of propagation of the seismic waves generated by the SPP, the azimuth of the fracture can be determined.
Inventors
- 👤 Daniel Silverman
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-01 14:00
CPC Classifications
G; G01; G01V; G01V1/00; G01V1/40; G01V1/42; G01V1/02; G01V1/133; G01V1/52
Claims Analysis
Total Claims: 28
Claim 1
Independent Claim
198 words
A method of creating a deep vertical fracture in an earth formation into which a deep borehole passes, comprising the steps of: (a) Inserting into said borehole from the surface a long pipe, and packing off a selected section, at a selected depth in said borehole, between said pipe and the wall of said borehole, so that the fluid in said pipe can flow to the wall of said borehole within said section. (b) pumping a selected fracturing fluid down said pipe to said section, at a selected average bottom hole pressure PA, where the average pressure PA is less than the normal fracturing pressure (NFP), normally required to fracture the rock in said borehole at said depth; while simultaneously (c) exposing the fluid in said section to a sequential plurality of closely spaced sharp pulses of positive shock pressure (SPPSP) of such magnitude that when superimposed on said bottom hole, average pressure PA will be higher than said (NPF), and high enough to cause incipient fractures in the rock wall of said borehole; whereby said borehole will be fractured at a lower average pressure than said NFP, normally required to fracture said borehole in the conventional manner.
Claim 2
Independent Claim
198 words
A method of creating a deep vertical fracture in an earth formation into which a deep borehole passes, comprising the steps of: (a) Inserting into said borehole from the surface a long pipe, and packing off a selected section, at a selected depth in said borehole, between said pipe and the wall of said borehole, so that the fluid in said pipe can flow to the wall of said borehole within said section. (b) pumping a selected fracturing fluid down said pipe to said section, at a selected average bottom hole pressure PA, where the average pressure PA is less than the normal fracturing pressure (NFP), normally required to fracture the rock in said borehole at said depth; while simultaneously (c) exposing the fluid in said section to a sequential plurality of closely spaced sharp pulses of positive shock pressure (SPPSP) of such magnitude that when superimposed on said bottom hole, average pressure PA will be higher than said (NPF), and high enough to cause incipient fractures in the rock wall of said borehole; whereby said borehole will be fractured at a lower average pressure than said NFP, normally required to fracture said borehole in the conventional manner.
Claim 3
Dependent Claim
50 words
The method as in claim 1 and including the steps of positioning, at at least three spaced points, at selected positions on or below the surface of the earth in the vicinity of said borehole, vibrational seismic sensors for detecting the seismic waves generated by said SPPSPs in said borehole.
Claim 4
Dependent Claim
33 words
The method as in claim 2 including the steps of detecting at said at least three points the horizontal shear seismic waves resulting from said pressure pulses; and determining their direction of propagation.
Claim 5
Dependent Claim
29 words
The method as in claim 2 including at least a part of a circular array of sensors centered at said borehole, and at a selected radius from said well.
Claim 6
Dependent Claim
19 words
The method as in claim 4 in which at least some of said sensors are compressional wave seismic sensors.
Claim 7
Dependent Claim
20 words
The method as in claim 4 in which said at least some of said sensors are shear wave seismic sensors.
Claim 8
Dependent Claim
36 words
The method as in claim 4 in which two of said circular array parts are superimposed with one compressional, and at least one shear sensor positioned at each of the points of at least two arrays.
Claim 9
Dependent Claim
32 words
The method as in claim 7 in which the detected signals from at least two sets of said sensors are compared with each other, at each of the points of an array.
Claim 10
Dependent Claim
57 words
The method as in claim 1 in which said at least one sharp pulse of fluid pressure is generated by the steps of (a) momentarily closing off at least a portion of the flow of said fluid in said pipe, near said section; and (b) after a selected short time interval again initiating the previous full flow.
Claim 11
Dependent Claim
32 words
The method as in claim 9 in which said step of closing off comprises the step of closing off a selected portion of the complete flow of said fluid through said pipe.
Claim 12
Dependent Claim
45 words
The method as in claim 5 in which at least two horizontal component compressional geophones are provided at each sensor point, and in which one component lies in a plane through the axis of said well, and the other component is perpendicular to that plane.
Claim 13
Dependent Claim
45 words
The method as in claim 5 in which said sensors at each of said points comprise two horizontal shear wave detectors, with their axes orthogonal to each other, in a horizontal plane, with the axis of one sensor in a radial plane to said borehole.
Claim 14
Dependent Claim
57 words
The method as in claim 5 in which said at least two points are part of a plurality of points arranged in two orthogonal straight lines, and in which a radial plane through the borehole passes through the junction between said two lines, and makes a selected angle with each of the vertical planes through said lines.
Claim 15
Dependent Claim
27 words
The method as in claim 1, including the step of continuing pumping of said fluid, and continuing said SPPSP's, whereby said fracture will be extended in length.
Claim 16
Dependent Claim
55 words
The method as in claim 14 and including the steps of detecting at a plurality of sensors, arranged at or near the surface of the earth in the vicinity of said well bore, in a two-dimensional array, the seismic waves set up at said fracture by said series of SPPSP's, and providing corresponding electrical signals.
Claim 17
Dependent Claim
21 words
The method as in claim 15 including the step of detecting by comparison of said electrical signals the directions of propagation.
Claim 18
Dependent Claim
34 words
The method as in claim 16 including the step of determining from said directions of arrival the time pattern of wave propagation from said fracture, and the azimuth and length of said vertical fracture.
Claim 19
Dependent Claim
21 words
The method as in claim 15 including the step of temporarily storing said received electrical signals, and stacking said electrical signals.
Claim 20
Dependent Claim
22 words
The method as in claim 18 including the step of determining from said stacked signals the direction of propagation of said waves.
Claim 21
Dependent Claim
26 words
The method as in claim 16 including the step of comparing said directions of propagation at successive spaced time intervals after the initiation of said fracture.
Claim 22
Independent Claim
79 words
The method of detecting the azimuth of a deep liquid-filled open fracture or fissure in the earth, comprising the steps of: (a) creating in said liquid in said fracture or fissure a plurality of sharp positive pulses of shock pressure (SPPSP); while (b) detecting at the surface, by means of a two-dimensional pattern of selected seismic sensors the pattern of seismic wave motion at or below the surface resulting from said plurality of sharp positive pulses of shock pressure.
Claim 23
Independent Claim
79 words
The method of detecting the azimuth of a deep liquid-filled open fracture or fissure in the earth, comprising the steps of: (a) creating in said liquid in said fracture or fissure a plurality of sharp positive pulses of shock pressure (SPPSP); while (b) detecting at the surface, by means of a two-dimensional pattern of selected seismic sensors the pattern of seismic wave motion at or below the surface resulting from said plurality of sharp positive pulses of shock pressure.
Claim 24
Dependent Claim
27 words
The method as in claim 21 including the additional step of determining the direction of arrival at at least two spaced sensors of said seismic wave motion.
Claim 25
Dependent Claim
20 words
The method as in claim 21 including the step of providing an increased hydrostatic pressure in said liquid-filled open fracture.
Claim 26
Dependent Claim
116 words
In a deep well drilled to a geological formation in which a vertical fracture has been formed and propped open, the method of determining the azimuth of said fracture comprising the steps of: (a) at each of a plurality of points spaced around said well at or near the surface of the earth, positioning at least one vibrational seismic sensor capable of detecting seismic waves in the earth, and generating corresponding electric signals; (b) creating at the bottom of said well a plurality of sharp positive pulses of shock pressure, capable of generating seismic waves in the earth; (c) recording the electrical signals from said sensors and determining the direction of propagation of said seismic waves.
Claim 27
Dependent Claim
116 words
In a deep well drilled to a geological formation in which a vertical fracture has been formed and propped open, the method of determining the azimuth of said fracture comprising the steps of: (a) at each of a plurality of points spaced around said well at or near the surface of the earth, positioning at least one vibrational seismic sensor capable of detecting seismic waves in the earth, and generating corresponding electric signals; (b) creating at the bottom of said well a plurality of sharp positive pulses of shock pressure, capable of generating seismic waves in the earth; (c) recording the electrical signals from said sensors and determining the direction of propagation of said seismic waves.
Claim 28
Dependent Claim
32 words
The method as in claim 24 including the additional step after step (a) and before step (b) of injecting a selected fluid at a selected pressure into the bottom of said well.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1987-02-13 | 1987-08-15 | 1988-02-14 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1991-02-13 | 1991-08-15 | 1992-02-14 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1995-02-13 | 1995-08-15 | 1996-02-14 | $7700.00 | Window Closed / Lapsed |