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US4486836A
Expired / Lapsed
US
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Well logging: utilizing superposition of step-profile responses of logging tools to improve logs
Assignee: Schlumberger Technology Corp
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Filing: 1981-12-22
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Granted: 1984-12-04
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Expires: 2001-12-22
Abstract
Abstract Disclosed is a method of improving well logs, such as induction logs and LATEROLOGS, by taking into account the effect on a log measurement both of the particular bed in which it is taken and of one or more other beds. In one example the process starts with an original induction log and a provisional layered formation which is based thereon and is characterized by bed boundaries and constant induction log levels within a bed. A provisional reconstructed log is built up by applying the tool response to the layered formation by a new technique which makes this expedient enough to be practicable. The reconstructed log is matched against the original log, and the layered formation is refined accordingly, by adding and/or shifting boundaries and/or by changing the measurement levels within beds, until the match is satisfactory. The original log is then converted to an improved log on the basis of the latest layered formation. Modifications include use of LATEROLOG measurements to improve LATEROLOGS and to improve induction logs.
Inventors
- 👤 Philippe J. Lacour-Gayet
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-29 19:20
CPC Classifications
G; G01; G01V; G01V3/00; G01V3/38
Claims Analysis
Total Claims: 15
Claim 1
Independent Claim
211 words
A well logging process comprising the following machine-implemented steps: deriving an original resistivity log produced by a resistivity tool passed through a borehole and exploring same with a sheet of current sent into the adjacent formation 1aterally of the borehole; finding, from said resistivity log, provisional bed boundary depth levels and bed resistivities of a provisional layered formation traversed by the borehole, said provisional bed boundaries and bed resistivities defining a provisional layered formation traversed by the borehole; producing, from said provisional boundary depth levels and bed resistivities, a provisional reconstructed resistivity log by linearly superposing respective known step profile responses of the tool to resistivity step profiles consistent with respective ones of said provisional boundaries and bed conductivities, wherein said step profile responses are selected to produce an accurate reconstructed measurement at a selected intermediate part of a bed squeezed between two shoulder beds having resistivities significantly different from that of the squeezed bed; matching the original log and the reconstructed log and refining the provisional bed resistivities and/or bed boundaries on the basis thereof until the match based on the most recent refinement meets selected criteria; and producing a tangible representation of an improved resistivity log based on the most recent set of refined bed boundaries and bed resistivities.
Claim 2
Dependent Claim
211 words
A well logging process comprising the following machine-implemented steps: deriving an original resistivity log produced by a resistivity tool passed through a borehole and exploring same with a sheet of current sent into the adjacent formation 1aterally of the borehole; finding, from said resistivity log, provisional bed boundary depth levels and bed resistivities of a provisional layered formation traversed by the borehole, said provisional bed boundaries and bed resistivities defining a provisional layered formation traversed by the borehole; producing, from said provisional boundary depth levels and bed resistivities, a provisional reconstructed resistivity log by linearly superposing respective known step profile responses of the tool to resistivity step profiles consistent with respective ones of said provisional boundaries and bed conductivities, wherein said step profile responses are selected to produce an accurate reconstructed measurement at a selected intermediate part of a bed squeezed between two shoulder beds having resistivities significantly different from that of the squeezed bed; matching the original log and the reconstructed log and refining the provisional bed resistivities and/or bed boundaries on the basis thereof until the match based on the most recent refinement meets selected criteria; and producing a tangible representation of an improved resistivity log based on the most recent set of refined bed boundaries and bed resistivities.
Claim 3
Dependent Claim
26 words
A well logging process as in claim 1 in which said tangible representation comprises a rectangularized log of the subsurface conductivity versus depth in the borehole.
Claim 4
Dependent Claim
35 words
A well logging process as in claim 1 in which said tangible representation comprises a non-rectangularized, improved resistivity log characterized by higher vertical resolution, including sharper response to thin beds, than the original resistivity log.
Claim 5
Dependent Claim
24 words
A well logging process as in claim 1 or 2 in which said tangible representation is a visible log trace on a record medium.
Claim 6
Dependent Claim
156 words
A well logging process comprising the following machine-implemented steps: passing an resistivity tool through a borehole to derive an original resistivity log thereof; finding, from a log of the same borehole or subsurface formation which can be said original resistivity log, provisional bed boundary depth levels and bed conductivities of a provisional layered formation traversed by the borehole; producing, from said provisional boundary depth levels and bed conductivities, a provisional reconstructed resistivity log by linearly superposing respective known step profile responses of the resistivity tool to conductivity step profiles consistent with respective ones of said provisional boundaries and bed conductivities; matching the original log and the reconstructed log and refining the provisional bed conductivities and/or bed boundaries on the basis thereof until the match based on the most recent refinement meets selected criteria; and producing a tangible representation of an improved resistivity log based on the most recent set of refined bed boundaries and bed conductivities.
Claim 7
Dependent Claim
156 words
A well logging process comprising the following machine-implemented steps: passing an resistivity tool through a borehole to derive an original resistivity log thereof; finding, from a log of the same borehole or subsurface formation which can be said original resistivity log, provisional bed boundary depth levels and bed conductivities of a provisional layered formation traversed by the borehole; producing, from said provisional boundary depth levels and bed conductivities, a provisional reconstructed resistivity log by linearly superposing respective known step profile responses of the resistivity tool to conductivity step profiles consistent with respective ones of said provisional boundaries and bed conductivities; matching the original log and the reconstructed log and refining the provisional bed conductivities and/or bed boundaries on the basis thereof until the match based on the most recent refinement meets selected criteria; and producing a tangible representation of an improved resistivity log based on the most recent set of refined bed boundaries and bed conductivities.
Claim 8
Dependent Claim
26 words
A well logging process as in claim 5 in which said tangible representation comprises a rectangularized log of the subsurface conductivity versus depth in the borehole.
Claim 9
Dependent Claim
35 words
A well logging process as in claim 5 in which said tangible representation comprises a non-rectangularized, improved resistivity log characterized by higher vertical resolution, including sharper response to thin beds, than the original resistivity log.
Claim 10
Dependent Claim
24 words
A well logging process as in claim 5 or 6 in which said tangible representation is a visible log trace on a record medium.
Claim 11
Dependent Claim
149 words
A well logging system comprising: means for deriving an original resistivity log produced by an resistivity tool passed through a borehole; and means for finding, from a log of the same borehole or subsurface formation which can be said original resistivity log, provisional bed boundary depth levels and bed conductivities of a provisional layered formation traversed by the borehole, producing therefrom a provisional reconstructed resistivity log by linearly superposing respective known step profile responses of the resistivity tool to conductivity step profiles consistent with respective ones of said provisional boundaries and bed conductivities, matching the original log and the reconstructed log and refining the provisional bed conductivities and/or bed boundaries on the basis thereof until the match based on the most recent refinement meets selected criteria, and producing a tangible representation of an improved resistivity log based on the most recent set of refined bed boundaries and bed conductivities.
Claim 12
Dependent Claim
149 words
A well logging system comprising: means for deriving an original resistivity log produced by an resistivity tool passed through a borehole; and means for finding, from a log of the same borehole or subsurface formation which can be said original resistivity log, provisional bed boundary depth levels and bed conductivities of a provisional layered formation traversed by the borehole, producing therefrom a provisional reconstructed resistivity log by linearly superposing respective known step profile responses of the resistivity tool to conductivity step profiles consistent with respective ones of said provisional boundaries and bed conductivities, matching the original log and the reconstructed log and refining the provisional bed conductivities and/or bed boundaries on the basis thereof until the match based on the most recent refinement meets selected criteria, and producing a tangible representation of an improved resistivity log based on the most recent set of refined bed boundaries and bed conductivities.
Claim 13
Dependent Claim
26 words
A well logging system as in claim 9 in which said tangible representation comprises a rectangularized log of the subsurface conductivity versus depth in the borehole.
Claim 14
Dependent Claim
35 words
A well logging system as in claim 9 in which said tangible representation comprises a non-rectangularized, improved resistivity log characterized by higher vertical resolution, including sharper response to thin beds, than the original resistivity log.
Claim 15
Dependent Claim
24 words
A well logging system as in claim 9 or 10 in which said tangible representation is a visible log trace on a record medium.
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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) | 1987-12-04 | 1988-06-04 | 1988-12-04 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1991-12-04 | 1992-06-04 | 1992-12-04 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1995-12-04 | 1996-06-04 | 1996-12-04 | $7700.00 | Window Closed / Lapsed |