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Patent US4663593A successfully refreshed from Google Patents.
US4663593A
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Method of electromagnetic exploration
Assignee: BP Corp North America Inc
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Filing: 1985-03-15
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Granted: 1987-05-05
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Expires: 2005-03-15
Abstract
Abstract A method of electromagnetic geophysical exploration of the earth's subterranean formations wherein an array of magnetometers are deployed at reference sites to obtain a measure of horizontal components of the earth's electromagnetic field and magnetometers are simultaneously deployed at a plurality of exploratory sites within a region of interest to obtain a measure of the vertical component of the earth's electromagnetic field. Resultant correlations of the horizontal and vertical components of the electromagnetic field can provide a multidimensional representation of the earth's resistivity structure.
Inventors
- 👤 Anthony G. Nekut, Jr.
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-03 08:41
CPC Classifications
G; G01; G01V; G01V3/00; G01V3/08; G01V3/082
Claims Analysis
Total Claims: 14
Claim 1
Independent Claim
73 words
A method of electromagnetic exploration comprising the following steps: (a) obtaining measures of two horizontal components of the earth's magnetic field at each of a plurality of reference sites; (b) obtaining a measure of the vertical component of the earth's magnetic field for at least one exploratory site; and (c) determining a measure of a multidimensional earth resistivity structure by correlating the measures of horizontal and vertical components of the earth's magnetic field.
Claim 2
Independent Claim
73 words
A method of electromagnetic exploration comprising the following steps: (a) obtaining measures of two horizontal components of the earth's magnetic field at each of a plurality of reference sites; (b) obtaining a measure of the vertical component of the earth's magnetic field for at least one exploratory site; and (c) determining a measure of a multidimensional earth resistivity structure by correlating the measures of horizontal and vertical components of the earth's magnetic field.
Claim 3
Dependent Claim
26 words
The method of claim 1 wherein at least three reference sites are employed to obtain a measure of the horizontal components of the earth's magnetic field.
Claim 4
Dependent Claim
27 words
The method of claim 1 wherein the spacing of reference sites from the exploratory sites, is a distance less than the wave length of the magnetic field.
Claim 5
Dependent Claim
30 words
The method of claim 1 wherein the spacing of the reference sites from the exploratory sites, is a distance greater than the depth of investigation into the earth's subterranean formations.
Claim 6
Dependent Claim
109 words
The method of claim 1 wherein the steps of determining a measure of a multidimensional earth resistivity structure includes: (a) obtaining a measure of a regional magnetic field from the measures of the horizontal components of the earth's magnetic field obtained at a plurality of reference sites; (b) obtaining a measure of regional field gradients from the measures of the horizontal components of the earth's magnetic field obtained at a plurality of reference sites; and (c) simultaneously Fourier transforming the regional horizontal magnetic field and field gradient measurements with the measurements of the vertical component of the magnetic field to obtain a measure of a multidimensional earth resistivity structure.
Claim 7
Dependent Claim
73 words
The method of claim 1 wherein the step (c) comprises correlating the regional magnetic field and field gradient measurements with the measurements of the vertical component of the magnetic field according to: ##EQU8## where <H x (ω)> and <H y (ω)> are measures of the horizontal components of the regional magnetic field; ##EQU9## are measures of the field gradients; and α's are transfer coefficients providing a multidimensional measure of the earth's resistivity structure.
Claim 8
Dependent Claim
19 words
The method of claim 1 further including the step of plotting the measures of the multidimensional earth resistivity structure.
Claim 9
Dependent Claim
53 words
The method of claim 1 wherein: as few as two fixed reference sites are employed to obtain a measure of the horizontal components of the earth's magnetic field; and the measurements of the vertical and horizontal components of the earth's magnetic field are at exploratory sites noncollinear with the fixed two reference sites.
Claim 10
Dependent Claim
30 words
The method of claim 6 wherein the transfer coefficients α x and α y provide a measure of the departure of the earth resistivity structure from a one dimensional condition.
Claim 11
Dependent Claim
26 words
The method of claim 6 wherein the transfer coefficients α xx , α yy and α xy provide a measure of the magnetic field penetration depth.
Claim 12
Dependent Claim
36 words
The method of claim 10 wherein the rate of change of transfer coefficients α xx , α yy and α xy with frequency provides a measure of the earth's resistivity at the magnetic field penetration depth.
Claim 13
Dependent Claim
26 words
The method of claim 6 further including plotting the magnitude of the transfer coefficient α x and α y as a function of location and frequency.
Claim 14
Dependent Claim
26 words
The method of claim 6 further including plotting the magnitude of the transfer coefficient α xx and α yy as a function of location and frequency.
References Cited (Backward Citations)
US4349781A
Cited
US4473800A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1990-05-04 | 1990-11-03 | 1991-05-05 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1994-05-04 | 1994-11-03 | 1995-05-05 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1998-05-04 | 1998-11-03 | 1999-05-05 | $7700.00 | Window Closed / Lapsed |