US4372380A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method for determination of fracture closure pressure
Assignee: BP Corp North America Inc
•
Filing: 1981-02-27
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Granted: 1983-02-08
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Expires: 2001-02-27
Abstract
Abstract A method of determining the minimum in-situ stress of an underground formation penetrated by a well. The method includes injecting a fluid at a certain rate into the formation to produce fractures in the formation, backflowing the injected fluid from the well at a rate less than the injection rate, and measuring the well fluid pressure decrease during the backflow to establish the pressure at which the fractures close.
Inventors
- 👤 Michael B. Smith
- 👤 Kenneth G. Nolte
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-29 00:30
CPC Classifications
E; E21; E21B; E21B49/00; E21B49/008; E21B43/00; E21B43/25; E21B43/26; E21B47/00; E21B47/06; E21B49/006
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
65 words
A method of determining the minimum in-situ stress of an underground formation penetrated by a well, comprising: (a) injecting fluid at a certain rate into the formation to open fractures in the formation; (b) backflowing the injected fluid at a rate less than the injection rate; and (c) monitoring the well fluid pressure during step (b) to establish the pressure at which the fractures close.
Claim 2
Independent Claim
65 words
A method of determining the minimum in-situ stress of an underground formation penetrated by a well, comprising: (a) injecting fluid at a certain rate into the formation to open fractures in the formation; (b) backflowing the injected fluid at a rate less than the injection rate; and (c) monitoring the well fluid pressure during step (b) to establish the pressure at which the fractures close.
Claim 3
Dependent Claim
14 words
A method as in claim 1 wherein the injection fluid is well fracturing fluid.
Claim 4
Dependent Claim
17 words
A method as in claim 1 wherein the backflow rate is approximately 10% of the injection rate.
Claim 5
Dependent Claim
15 words
A method as in claim 1 wherein the well fluid pressure is the bottomhole pressure.
Claim 6
Dependent Claim
30 words
A method as in claim 1 wherein the decrease in well fluid pressure is monitored to establish a point of pressure rate change which indicates the closure of the fractures.
Claim 7
Dependent Claim
73 words
An improved method for determining the fracture closure pressure for waterflood control, comprising: injecting fluid at a certain rate into the formation to positively open fractures in the formation; shutting in the well; backflowing the injected liquid from the well at a rate less than the injection rate; and monitoring the rate of decrease in the well fluid pressure to determine a point of pressure rate change indicating the closure of the fractures.
Claim 8
Dependent Claim
73 words
An improved method for determining the fracture closure pressure for waterflood control, comprising: injecting fluid at a certain rate into the formation to positively open fractures in the formation; shutting in the well; backflowing the injected liquid from the well at a rate less than the injection rate; and monitoring the rate of decrease in the well fluid pressure to determine a point of pressure rate change indicating the closure of the fractures.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1986-02-07 | 1986-08-09 | 1987-02-08 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1990-02-07 | 1990-08-09 | 1991-02-08 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1994-02-07 | 1994-08-09 | 1995-02-08 | $7700.00 | Window Closed / Lapsed |