US3739871A
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Mapping of earth fractures induced by hydrafracturing
Assignee: SENTURION SCIENCES Inc
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Filing: 1971-07-30
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Granted: 1973-06-19
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Expires: 1991-07-30
Abstract
Abstract In the process of inducing fractures in the earth in the vicinity of a bore hole, fluid under high pressure is pumped down the well bore, and a portion of the wall of the well bore is exposed to this pressure at a known position in the earth. As the fluid pressure is increased, the rock will part, or rupture, and form a fracture. As the fluid rapidly flows into this fracture the pressure sharply falls, and this drop in pressure is transmitted to the surface, where at some time later, the pressure in the well fluid at the surface will show a corresponding drop. Sensors are placed in the earth around the well bore to receive the seismic wave that is generated by the rock fracture. The times of arrival of the seismic wave can be determined from a display, and the average velocity of seismic waves in the earth can be determined. As the flow of fluid continues, the pressurized fluid flows into the fracture, causing it to widen and extend to greater distances from the well bore. This extension is discontinuous and intermittent, involving additional rock fractures and corresponding seismic signals. The times of arrival of the later fracture signals are determined. From these determinations and the previously determined velocity of seismic waves, the position in the earth of the successive fractures are determined.
Inventors
- 👤 J Bailey
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-27 20:26
CPC Classifications
G; G01; G01V; G01V1/00; G01V1/40; G01V1/42; E; E21; E21B; E21B43/00; E21B43/25; E21B43/26; E21B47/00; E21B47/02; E21B47/12; E21B47/14; G01V2210/00; G01V2210/10; G01V2210/16; G01V2210/161
Claims Analysis
Total Claims: 22
Claim 1
Independent Claim
165 words
In the process of fracturing earth rock formations by pumping under pressure a selected fluid into a bore hole to a depth selected to induce said fracture, the position in the earth of the point of application of pressure being known, the method of mapping the fracture induced in the rocks in the vicinity of said point application, comprising the steps of: a. placing a plurality of sensors in the earth in a pattern around said point of application, said sensors adapted to detect and transduce vibrations of the earth, caused by said inducement of said fracture, to corresponding electrical signals; b. pumping said fluid under pressure into said bore hole to induce a first fracture of the rock at said point of application of said fluid pressure; c. amplifying said electrical signals; d. recording as a function of time said amplified signals; and e. continue pumping said fluid under pressure to induce a second fracture of said rock and repeating steps (c) and (d).
Claim 2
Dependent Claim
165 words
In the process of fracturing earth rock formations by pumping under pressure a selected fluid into a bore hole to a depth selected to induce said fracture, the position in the earth of the point of application of pressure being known, the method of mapping the fracture induced in the rocks in the vicinity of said point application, comprising the steps of: a. placing a plurality of sensors in the earth in a pattern around said point of application, said sensors adapted to detect and transduce vibrations of the earth, caused by said inducement of said fracture, to corresponding electrical signals; b. pumping said fluid under pressure into said bore hole to induce a first fracture of the rock at said point of application of said fluid pressure; c. amplifying said electrical signals; d. recording as a function of time said amplified signals; and e. continue pumping said fluid under pressure to induce a second fracture of said rock and repeating steps (c) and (d).
Claim 3
Dependent Claim
30 words
The method as in claim 1 including the additional step of recording as a function of time the pressure in said pressurized fluid at the top of said bore hole.
Claim 4
Dependent Claim
36 words
The method as in claim 2 including the additional step of determining from said recorded pressure the time of occurrence of a sharp pressure drop corresponding to the time of fracturing, at said point of application.
Claim 5
Dependent Claim
60 words
The method as in claim 3 including the step of determining from the known length of bore hole from the top of the bore hole to the point of application of pressure, the time of travel of the rarefaction wave from said fracture initiation to the surface pressure gauge, whereby the time of the first fracture initiation can be determined.
Claim 6
Dependent Claim
40 words
The method as in claim 4 including the step, from the known position and known time of the first fracture, of determining the average velocity of propagation of seismic waves in the earth in the vicinity of said well bore.
Claim 7
Dependent Claim
35 words
The method as in claim 5 including the step, from the known average seismic velocity, and the times of arrival of seismic signals from a second fracture, of determining the position of said second fracture.
Claim 8
Dependent Claim
53 words
The method as in claim 2 in which the pressurized fluid is transmitted to the formation by means of tubing in the bore hole, and including the additional step of creating a sudden release of pressure at the bottom end of the tubing, while recording the amplified transduced signals and the surface pressure.
Claim 9
Dependent Claim
16 words
The method as in claim 1 wherein the sensors as at the surface of the earth.
Claim 10
Dependent Claim
17 words
The method as in claim 1 wherein the sensors are buried below the surface of the earth.
Claim 11
Dependent Claim
24 words
The method as in claim 1 wherein at least part of the sensors are positioned in deep bore holes surrounding the pressurized bore hole.
Claim 12
Dependent Claim
13 words
The method as in claim 1 wherein the sensors are vertical component geophones.
Claim 13
Dependent Claim
17 words
The method as in claim 1 wherein at least part of the sensors are horizontal component geophones.
Claim 14
Dependent Claim
30 words
The method as in claim 1 wherein the surface of the earth at the bore hole has an overlying layer of water and the sensors are positioned in the water.
Claim 15
Dependent Claim
28 words
The method as in claim 1 wherein the horizontal dimension of the pattern of sensors is at least as great as the depth of said point of application.
Claim 16
Dependent Claim
28 words
The method as in claim 1 including the additional step of closing the well bore under the pressure of the pressurized fluid and continuing to record said signals.
Claim 17
Dependent Claim
28 words
The method as in claim 1 including the additional step of determining the pattern of the times of arrival of the fracture initiation at each of the sensors.
Claim 18
Dependent Claim
18 words
The method as in claim 16 including the step of correlating each of the recorded traces in pairs.
Claim 19
Dependent Claim
39 words
The method as in claim 1 including the additional steps of making an harmonic analysis of the received signals, determining the characteristic frequency of said signals, and filtering said recorder traces with a band-pass filter including said characteristic frequency.
Claim 20
Dependent Claim
43 words
The method as in claim 16 including the steps of shifting each of a plurality traces in accordance with said pattern so that all of the signals on said traces are in coincidence, and adding said shifted traces to provide a sum trace.
Claim 21
Dependent Claim
96 words
The method as in claim 1 including the additional steps of: a. selecting a time of fracture at said first fracture; b. from the known distances from the point of first fracture to each of said sensors and the times of arrival of said vibrations at said sensors calculating the average velocity of propagation of said vibrations through the earth; c. comparing the values of average velocity for each of the paths to each sensor; and d. repeating steps (a), (b) and (c) until said calculated average velocity is substantially the same for each said path.
Claim 22
Dependent Claim
80 words
The method as in claim 20 including the additional steps of: a. selecting a time of fracture at said second fracture; b. from the known average velocity and the known times of arrival of said vibrations at said sensors calculating the distance from each of said sensors to the position of said second fracture; c. determining the position of said second fracture; and d. repeating steps (a), (b), and (c) until sequential values of said position are substantially the same.
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) | 1976-06-18 | 1976-12-18 | 1977-06-19 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-06-18 | 1980-12-18 | 1981-06-19 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-06-18 | 1984-12-18 | 1985-06-19 | $7700.00 | Window Closed / Lapsed |