US5345819A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method and apparatus for wellbore stability analysis
Assignee: Chevron USA Inc
•
Filing: 1990-10-22
•
Granted: 1994-09-13
•
Expires: 2010-10-22
Abstract
Abstract Method and apparatus for the nondestructive testing of rock samples as a function of time are disclosed. A rock sample is placed in a sample vessel which simulates in-situ wellbore conditions of pressure, temperature and fluid effects. Ultrasonic signals are transmitted through the sample and the transit time is measured. The measurements are repetitively performed and the time history of the development of strength is recorded in order to determine when the rock sample begins to weaken.
Inventors
- 👤 Harry L. Dearing, Jr.
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-08 21:12
CPC Classifications
G; G01; G01N; G01N29/00; G01N29/04; G01N29/07; G01N29/22; G01N29/227; G01N29/228; G01N33/00; G01N33/24; G01N2291/00; G01N2291/02; G01N2291/024; G01N2291/02441; G01N2291/10; G01N2291/102
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
128 words
An apparatus for determining wellbore stability comprising: a. means for housing a prismatic shaped rock sample and for controlling the pressure and temperature of the sample, and means for exposing a face of said sample that is not subject to axial loading to a drilling fluid; b. means for generating an ultrasonic signal coupled to said rock sample; c. means for measuring the transit time of said ultrasonic signal to travel through said rock sample over a period of time and for generating a measurement signal representative thereof while said sample is exposed to said drilling fluid; and d. means, responsive to said measurement signal, for generating according to a predetermined relationship relating said transit time to strength, a signal representative of said strength of said rock sample.
Claim 2
Independent Claim
128 words
An apparatus for determining wellbore stability comprising: a. means for housing a prismatic shaped rock sample and for controlling the pressure and temperature of the sample, and means for exposing a face of said sample that is not subject to axial loading to a drilling fluid; b. means for generating an ultrasonic signal coupled to said rock sample; c. means for measuring the transit time of said ultrasonic signal to travel through said rock sample over a period of time and for generating a measurement signal representative thereof while said sample is exposed to said drilling fluid; and d. means, responsive to said measurement signal, for generating according to a predetermined relationship relating said transit time to strength, a signal representative of said strength of said rock sample.
Claim 3
Dependent Claim
64 words
The apparatus of claim 1 and further comprising; a. control means for controlling said means for generating said ultrasonic signal and said measurement means to repetitively perform measurements of transit time and strength; and b. means for recording said repetitive measurements of said strength representative signal as a function of time, thereby to provide a time history of the strength of said rock sample.
Claim 4
Dependent Claim
26 words
The apparatus of claim 1 wherein said means for generating an ultrasonic signal through the rock sample comprises ultrasonic transducers on opposite sides of said sample.
Claim 5
Independent Claim
91 words
A method for non-destructively measuring the strength of a rock sample having at least one face, comprising the steps of: a. maintaining a rock sample at a controlled temperature and pressure and passing a drilling fluid over one face of said sample; b. transmitting an ultrasonic signal through the sample; c. detecting said ultrasonic signal subsequent to its transiting the sample and measuring the time required for said signal to transit the sample; and d. determining, according to a predetermined relationship relating transit time to strength, the strength of the sample.
Claim 6
Independent Claim
91 words
A method for non-destructively measuring the strength of a rock sample having at least one face, comprising the steps of: a. maintaining a rock sample at a controlled temperature and pressure and passing a drilling fluid over one face of said sample; b. transmitting an ultrasonic signal through the sample; c. detecting said ultrasonic signal subsequent to its transiting the sample and measuring the time required for said signal to transit the sample; and d. determining, according to a predetermined relationship relating transit time to strength, the strength of the sample.
Claim 7
Dependent Claim
12 words
A method according to claim 4 wherein the rock sample is shale.
Claim 8
Dependent Claim
23 words
A method according to claim 4 wherein the pressure is an axial load of 1,000-10,000 psi and a confining stress of 500-9,000 psi.
Claim 9
Dependent Claim
12 words
A method according to claim 4 wherein said drilling fluid is mud.
Claim 10
Dependent Claim
12 words
A method according to claim 4 wherein said rock sample is prismatic-shaped.
References Cited (Backward Citations)
US2531083A
Cited
US3139747A
Cited
US4380930A
Cited
US4486714A
Cited
US4487056A
Cited
US4561289A
Cited
US4753107A
Cited
US5025668A
Cited
US4907448A
Cited
US5069065A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1997-09-12 | 1998-03-14 | 1998-09-13 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2001-09-12 | 2002-03-14 | 2002-09-13 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2005-09-12 | 2006-03-14 | 2006-09-13 | $7700.00 | Window Closed / Lapsed |