US4779200A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method for estimating porosity and/or permeability
Assignee: Schlumberger Technology Corp
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Filing: 1985-07-16
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Granted: 1988-10-18
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Expires: 2005-07-16
Abstract
Abstract In a drill stem test, a packer is set in the well bore to isolate a potential producing zone. A drill pipe with a down hole valve is fitted through the packer. The pipe is usually partially filled with a liquid column prior to commencement of the test, which essentially comprises opening the valve so that formation fluids can flow into the drill pipe and measuring various parameters associated with the fluid transfer. A method for estimating porosity and/or permeability includes the steps of setting up such a drill stem test wherein flow of formation fluid to a drill pipe may be controlled by a down hole valve, opening the valve to establish a flow, recording flow parameters, and analyzing oscillatory transients in the flow to compute therefrom estimates of porosity and permeability.
Inventors
- 👤 Leslie J. S. Bradbury
- 👤 David B. White
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-31 12:21
CPC Classifications
E; E21; E21B; E21B49/00; E21B49/008
Claims Analysis
Total Claims: 20
Claim 1
Independent Claim
120 words
A method for investigating the oil producing potential of a subsurface formation zone surrounding a well bore, said method comprising the steps of: (a) installing in proximity to said subsurface formation zone, drill stem test equipment capable of controlling the flow of formation fluid out of the formation zone; (b) establishing by the operation of said drill stem test equipment, a downhole flow condition in which formation fluids flow out of the formation zone while exhibiting an initial, naturally damped oscillatory behavior dependent on characteristics of said formation; (c) detecting a time varying characteristic of said initial, naturally damped oscillatory behavior and generating a signal indicative thereof; and (d) in response to said signal, determining a characteristic of said formation.
Claim 2
Independent Claim
120 words
A method for investigating the oil producing potential of a subsurface formation zone surrounding a well bore, said method comprising the steps of: (a) installing in proximity to said subsurface formation zone, drill stem test equipment capable of controlling the flow of formation fluid out of the formation zone; (b) establishing by the operation of said drill stem test equipment, a downhole flow condition in which formation fluids flow out of the formation zone while exhibiting an initial, naturally damped oscillatory behavior dependent on characteristics of said formation; (c) detecting a time varying characteristic of said initial, naturally damped oscillatory behavior and generating a signal indicative thereof; and (d) in response to said signal, determining a characteristic of said formation.
Claim 3
Dependent Claim
24 words
A method as claimed in claim 1, wherein said characteristic of said formation is the product of porosity and the permeability of the formation.
Claim 4
Dependent Claim
23 words
A method as claimed in claim 2, wherein said determining step includes determining the frequency of oscillation of said naturally damped oscillatory behavior.
Claim 5
Dependent Claim
30 words
A method as claimed in claim 3, wherein the permeability-porosity product is estimated from the formula ##EQU7## where n, n o , ε, k and φ are as hereinbefore defined.
Claim 6
Dependent Claim
21 words
A method as claimed in claim 2, wherein said determining step includes determining the damping of said naturally damped oscillatory behavior.
Claim 7
Dependent Claim
26 words
A method as claimed in claim 5, wherein the permeability-porosity product is estimated from the formula ##EQU8## where c, k and φ are as hereinbefore defined.
Claim 8
Dependent Claim
14 words
A method as claimed in claim 1, wherein said detecting step includes measuring pressure.
Claim 9
Dependent Claim
15 words
A method as claimed in claim 1, wherein said determining step includes measuring flow velocity.
Claim 10
Dependent Claim
22 words
A method as claimed in claim 8, wherein said computing step comprises determining the peak oscillatory flow velocity and estimating porosity therefrom.
Claim 11
Dependent Claim
39 words
A method as claimed in claim 9, wherein porosity is estimated from the formula ##EQU9## where V osc , p i , ρ, g, L o , A, r w , h, φ and c are as hereinbefore defined.
Claim 12
Dependent Claim
27 words
A method as claimed in claim 8, wherein said determining step further comprises determining the peak non-oscillatory flow velocity and estimating the permeability of the formation therefrom.
Claim 13
Dependent Claim
36 words
A method as claimed in claim 11, wherein permeability is estimated from the formula ##EQU10## where V s , k, μ, p i , ρ, g, L o , A and h are as hereinbefore defined.
Claim 14
Dependent Claim
16 words
The method as claimed in claim 1 wherein said characteristic of said formation relates to permeability.
Claim 15
Dependent Claim
19 words
A method as claimed in claim 13, wherein said determining step includes determining the frequency of said oscillatory transients.
Claim 16
Dependent Claim
19 words
A method as claimed in claim 13, wherein said determining step includes determining the damping of said oscillatory transient.
Claim 17
Dependent Claim
14 words
A method as claimed in claim 13, wherein said detecting step includes measuring pressure.
Claim 18
Dependent Claim
15 words
A method as claimed in claim 13, wherein said detecting step includes measuring flow velocity.
Claim 19
Dependent Claim
22 words
A method as claimed in claim 17, wherein said determining step comprises determining the peak non-oscillatory flow velocity and estimating permeability therefrom.
Claim 20
Dependent Claim
36 words
A method as claimed in claim 18, wherein permeability is estimated from the formula ##EQU11## where V s , k, μ, p i , ρ, g, L o , A and h are as hereinbefore defined.
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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) | 1991-10-18 | 1992-04-18 | 1992-10-18 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1995-10-18 | 1996-04-18 | 1996-10-18 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1999-10-18 | 2000-04-18 | 2000-10-18 | $7700.00 | Window Closed / Lapsed |