US4981037A
Expired / Lapsed
US
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Method for determining pore pressure and horizontal effective stress from overburden and effective vertical stresses
Assignee: Halliburton Energy Services Inc
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Filing: 1986-05-28
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Granted: 1991-01-01
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Expires: 2006-05-28
Abstract
Abstract The porosity-effective stress relationship, which is a fuction of lithology, is used to calculate total overburden stress, vertical effective stress, horizontal effective stress and pore pressure using well log data. The log data can be either real time data derived from measurement-while-drilling equipment or open hole wireline logging equipment.
Inventors
- 👤 Phil Holbrook
- 👤 Homer A. Robertson
- 👤 Michael L. Hauck
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-02 16:30
CPC Classifications
E; E21; E21B; E21B47/00; E21B47/06; E21B49/00; E21B49/006
Claims Analysis
Total Claims: 5
Claim 1
Independent Claim
153 words
A method for determining pore pressure in an in situ subsurface formation, comprising the steps of: causing a well logging tool to traverse an earth borehole between the earth's surface and said subsurface formation; determining the total overburden stress resulting from the integrated weight of material overlying said subsurface formation between the earth's surface and said subsurface formation, said overburden stress determining step being a function of the density of the solid rock portion and of the density of the fluid filling the pore spaces in the said overlying materials as measured, at least in part, by said well logging tool; determining the vertical effective stress in said subsurface formation from porosity logs, said porosity logs being generated by said well logging tool as said tool traverses said earth borehole through said subsurface formation; and generating a pore pressure log indicative of the difference between said overburden stress and said vertical effective stress.
Claim 2
Independent Claim
153 words
A method for determining pore pressure in an in situ subsurface formation, comprising the steps of: causing a well logging tool to traverse an earth borehole between the earth's surface and said subsurface formation; determining the total overburden stress resulting from the integrated weight of material overlying said subsurface formation between the earth's surface and said subsurface formation, said overburden stress determining step being a function of the density of the solid rock portion and of the density of the fluid filling the pore spaces in the said overlying materials as measured, at least in part, by said well logging tool; determining the vertical effective stress in said subsurface formation from porosity logs, said porosity logs being generated by said well logging tool as said tool traverses said earth borehole through said subsurface formation; and generating a pore pressure log indicative of the difference between said overburden stress and said vertical effective stress.
Claim 3
Dependent Claim
44 words
The method according to claim 1 wherein said vertical effective stress is determined from σ v = σ max .sup.(1-φ) 1+α, where σ v =vertical effective stress, σ max =theoretical maximum vertical effective stress, φ=fluid filled porosity, and α=compaction exponent relating stress to strain.
Claim 4
Dependent Claim
32 words
The method according to claim 2 wherein said σ max is determined from lithology logs generating by said well logging tool as said tool traverse said earth borehole through said subsurface formation.
Claim 5
Dependent Claim
47 words
The method according to claim 1, being characterized further by the additional step of determining the effective horizontal stress at said subsurface formation using lithology logs generated, at least in part, by said well logging tool as said tool traverses said earth borehole through said subsurface formation.
References Cited (Backward Citations)
US3907034A
Cited
US4635719A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1993-12-31 | 1994-07-02 | 1995-01-01 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1997-12-31 | 1998-07-02 | 1999-01-01 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2001-12-31 | 2002-07-02 | 2003-01-01 | $7700.00 | Window Closed / Lapsed |