US4473800A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method for detecting magnetotelluric subsurface anomalies
Assignee: Mobil Oil AS
•
Filing: 1982-09-21
•
Granted: 1984-09-25
•
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 05:53
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.
References Cited (Backward Citations)
US2034447A
Cited
US2140798A
Cited
US2284990A
Cited
US2586667A
Cited
US3188559A
Cited
US3309607A
Cited
US3496768A
Cited
US3778701A
Cited
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 |