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US4473800A
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Method for detecting magnetotelluric subsurface anomalies
Assignee: Mobil Oil AS
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Filing: 1982-09-21
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Granted: 1984-09-25
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Expires: 2002-09-21
Abstract
Abstract A method for removing the effects of said subsurface anomalies in magnetotelluric survey data is disclosed wherein resistivity curves are compared and a correction factor is determined. Resistivity curves having a deviation from a mean are multiplied by this correction factor.
Inventors
- 👤 Barry N. Warner
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-09 06:12
CPC Classifications
G; G01; G01V; G01V3/00; G01V3/38; G01V3/08; G01V3/082
Claims Analysis
Total Claims: 5
Claim 1
Independent Claim
172 words
A method for detecting subsurface anomalies in vertical magnetotelluric surveys where a first pair and a second pair of electrodes in a perpendicular pattern at a single location are used to collect data where resistivity is plotted as a function of frequency and frequency may be correlated to depth, said method comprising the steps of: receiving a first set of data consisting of resistivity points as a function of frequency from the first pair of electrodes at a first location: receiving a second set of data consisting of resistivity points as a function of frequency from the second pair of electrodes at said first location; computing a difference between said first set of data and said second set of data to produce a difference set consisting of resistivity points as a function of frequency; displaying said difference set as a graphical plot; and; identifying a first subsurface anomaly whenever said plot of said difference set exceeds a predetermined amount and produces a DC like bias shifting said plot of said difference set.
Claim 2
Independent Claim
172 words
A method for detecting subsurface anomalies in vertical magnetotelluric surveys where a first pair and a second pair of electrodes in a perpendicular pattern at a single location are used to collect data where resistivity is plotted as a function of frequency and frequency may be correlated to depth, said method comprising the steps of: receiving a first set of data consisting of resistivity points as a function of frequency from the first pair of electrodes at a first location: receiving a second set of data consisting of resistivity points as a function of frequency from the second pair of electrodes at said first location; computing a difference between said first set of data and said second set of data to produce a difference set consisting of resistivity points as a function of frequency; displaying said difference set as a graphical plot; and; identifying a first subsurface anomaly whenever said plot of said difference set exceeds a predetermined amount and produces a DC like bias shifting said plot of said difference set.
Claim 3
Dependent Claim
31 words
The method according to claim 1 also including the step of: determining the depth of said first subsurface anomaly by correlating the frequency of the occurrence of said bias with depth.
Claim 4
Dependent Claim
39 words
The method according to claim 1 wherein said identifying step includes the step of: identifying a second subsurface anomaly whenever said plot of said difference set produces a second DC like bias shifting said plot of said difference set.
Claim 5
Dependent Claim
36 words
The method according to claim 3 also including the step of: determining the depth of said first subsurface anomaly and said second subsurface anomaly by correlating the frequency of the occurrence of said bias with depth.
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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) | 1987-09-25 | 1988-03-26 | 1988-09-25 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1991-09-25 | 1992-03-26 | 1992-09-25 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1995-09-25 | 1996-03-26 | 1996-09-25 | $7700.00 | Window Closed / Lapsed |