US3766994A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Abnormal pressure detection during drilling of a well
Assignee: ConocoPhillips Co
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Filing: 1971-10-01
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Granted: 1973-10-23
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Expires: 1991-10-01
Abstract
Abstract An early warning detection method for predicting abnormal formation pressure in subterranean rock strata before it is drilled. The technique is to measure the concentration of sulfate or carbonate ions in the formation being drilled, while the well is being drilled in the normally pressured rock strata existing above the abnormally pressured formations. When variations are observed in the degree of change of the amount of sulfate or carbonate ions present with depth, drilling procedures are altered to meet the requirements of the formation which is about to be penetrated by the drill bit.
Inventors
- 👤 W Fertl
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-01 01:03
CPC Classifications
E; E21; E21B; E21B49/00; E21B49/005
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
113 words
A method for detecting the approach of an underlying abnormally pressured zone while drilling a well in normally pressured zones of a subterranean strata comprising: a. drilling the normally pressured zones with a drilling fluid whose pressure is balanced against the subterranean strata pressure, b. monitoring the concentration of the sulfate ion or the carbonate ion in the subterranean strata being drilled, c. when the rate of change of concentration of the sulfate ion or the carbonate ion with depth begins to change, instituting controlled drilling procedures, and d. when the abnormally pressured zone is penetrated, adjusting the drilling fluid pressure to balance the same against the pressure in the abnormally pressured zone.
Claim 2
Independent Claim
113 words
A method for detecting the approach of an underlying abnormally pressured zone while drilling a well in normally pressured zones of a subterranean strata comprising: a. drilling the normally pressured zones with a drilling fluid whose pressure is balanced against the subterranean strata pressure, b. monitoring the concentration of the sulfate ion or the carbonate ion in the subterranean strata being drilled, c. when the rate of change of concentration of the sulfate ion or the carbonate ion with depth begins to change, instituting controlled drilling procedures, and d. when the abnormally pressured zone is penetrated, adjusting the drilling fluid pressure to balance the same against the pressure in the abnormally pressured zone.
Claim 3
Dependent Claim
27 words
The method of claim 1 wherein the controlled drilling procedures instituted comprise keeping a constant rotary speed and weight on the bit while monitoring the penetration rate.
Claim 4
Dependent Claim
25 words
The method of claim 1 wherein the concentration of sulfate ion or carbonate ion is measured continually on samples of formation circulated from the well.
Claim 5
Independent Claim
113 words
A method for detecting the approach of an underlying geopressure zone while drilling normally pressured subterranean strata comprising: a. drilling the normally pressured subterranean strata with a drilling fluid whose pressure is balanced against the subterranean strata pressure, b. monitoring the concentration of the sulfate ion or the carbonate ion in the subterranean strata being drilled, c. when the concentration of sulfate ion or carbonate ion in the subterranean strata begins to change rapidly with change in depth, instituting controlled drilling procedures, and d. when the controlled drilling procedures indicate that a geopressured zone has been penetrated, increasing the drilling fluid pressure to balance the same against the pressure in the geopressured zone.
Claim 6
Independent Claim
113 words
A method for detecting the approach of an underlying geopressure zone while drilling normally pressured subterranean strata comprising: a. drilling the normally pressured subterranean strata with a drilling fluid whose pressure is balanced against the subterranean strata pressure, b. monitoring the concentration of the sulfate ion or the carbonate ion in the subterranean strata being drilled, c. when the concentration of sulfate ion or carbonate ion in the subterranean strata begins to change rapidly with change in depth, instituting controlled drilling procedures, and d. when the controlled drilling procedures indicate that a geopressured zone has been penetrated, increasing the drilling fluid pressure to balance the same against the pressure in the geopressured zone.
Claim 7
Dependent Claim
27 words
The method of claim 4 wherein the controlled drilling procedures instituted comprise keeping a constant rotary speed and weight on the bit while monitoring the penetration rate.
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) | 1976-10-22 | 1977-04-23 | 1977-10-23 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-10-22 | 1981-04-23 | 1981-10-23 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-10-22 | 1985-04-23 | 1985-10-23 | $7700.00 | Window Closed / Lapsed |