Patent US5095272A successfully refreshed from Google Patents.
US5095272A
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Methods for determining formation dip and strike using high frequency phase shift
Assignee: Halliburton Logging Services Inc
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Filing: 1990-03-23
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Granted: 1992-03-10
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Expires: 2010-03-23
Abstract
Abstract A dipmeter has a coil forming a medium frequency field (e.g., five megahertz); the field interacts with the formation to form induced currents in the formations dependent on resistivity. The formation boundaries create a phase shift contrasting with the shift occurring in the formation so that a pair of closely spaced coils on a shoe locates relative transition of a formation boundary. The boundary is located by the several dipmeter arms.
Inventors
- 👤 Paul Sinclair
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-09 16:01
CPC Classifications
G; G01; G01V; G01V3/00; G01V3/18; G01V3/26; G01V3/28; E; E21; E21B; E21B47/00; E21B47/02; E21B47/026
Claims Analysis
Total Claims: 13
Claim 1
Independent Claim
217 words
A method of determining bed boundary dip in a well borehole, comprising the steps of: (a) forming a moving AC field in the earth formations adjacent to a well borehole by causing an AC current flow in the megahertz frequency range through a transmitter coil wherein the field induces currents to flow in the formations adjacent to the well borehole wherein the phase shift of the induced currents are dependent on formation resistivity; (b) measuring phase shift at multiple azimuthal locations along the sidewall of the well borehole by moving along the sidewall of the well borehole at least three pair of longitudinally separated offset coil means each of which have field induced signals formed therein wherein the induced signals are compared to form at least three azimuthally separated phase shift signals; (c) signal processing said at least three phase shift signals by applying a normalized differential phase shift algorithm wherein a dimensionless quantity is computed for successive depth samples of phase shift at each of said at least three offset coil pairs for comparison and accurate correlation to determine dip and strike angles of bed boundaries versus depth; and (d) as a function of differential phase shift, determining movement of a bed boundary relative to each of said at least three pairs of said coil means.
Claim 2
Independent Claim
217 words
A method of determining bed boundary dip in a well borehole, comprising the steps of: (a) forming a moving AC field in the earth formations adjacent to a well borehole by causing an AC current flow in the megahertz frequency range through a transmitter coil wherein the field induces currents to flow in the formations adjacent to the well borehole wherein the phase shift of the induced currents are dependent on formation resistivity; (b) measuring phase shift at multiple azimuthal locations along the sidewall of the well borehole by moving along the sidewall of the well borehole at least three pair of longitudinally separated offset coil means each of which have field induced signals formed therein wherein the induced signals are compared to form at least three azimuthally separated phase shift signals; (c) signal processing said at least three phase shift signals by applying a normalized differential phase shift algorithm wherein a dimensionless quantity is computed for successive depth samples of phase shift at each of said at least three offset coil pairs for comparison and accurate correlation to determine dip and strike angles of bed boundaries versus depth; and (d) as a function of differential phase shift, determining movement of a bed boundary relative to each of said at least three pairs of said coil means.
Claim 3
Dependent Claim
18 words
The method of claim 1 including the step of observing differential phase shift increase to identify a boundary.
Claim 4
Dependent Claim
80 words
The method of claim 1 wherein the coil is centered in the well borehole on the axis thereof to form a field around the well borehole wherein the field is continuously formed along a portion of the well borehole, and positioning said offset coil means parallel to the well borehole axis to detect phase shift along the length of the well borehole so that relative movement of a formation boundary through the field forms a change in the phase shift.
Claim 5
Dependent Claim
23 words
The method of claim 3 including the step of offsetting said coil means by a distance along the axis of the well borehole.
Claim 6
Dependent Claim
14 words
The method of claim 4 wherein the offset distance is less than 0.5 inches.
Claim 7
Dependent Claim
15 words
The method of claim 1 wherein the phase shift is independent of the signal amplitude.
Claim 8
Dependent Claim
18 words
The method of claim 1 wherein the phase shift is measured at the frequency of the AC field.
Claim 9
Dependent Claim
39 words
The method of claim 1 wherein the offset coil means forms two separate signals, and including the steps of amplifying the two signals, and thereafter comparing the phase of the two signals to obtain a phase shift output signal.
Claim 10
Dependent Claim
40 words
The method of claim 8 including the step of mounting said offset coil means on an arm extending toward the sidewall of the well borehole, and further measuring additional differential phase shift signal at multiple locations around the well borehole.
Claim 11
Dependent Claim
30 words
The method of claim 1 wherein the offset coil means forms two separate signals and thereafter demodulating the phase of the two signals to obtain a phase shift output signal.
Claim 12
Dependent Claim
28 words
The method of claim 9 including the step of positioning said offset coil means in a sacrificial wear member for contact with the sidewall of the well borehole.
Claim 13
Dependent Claim
51 words
The method of claim 1 in which the algorithm includes taking the modulus of the difference between phase shift measured at two successive depths and dividing the result by the geometric mean of the two phase shifts, producing a dimensionless quantity indicative only of the spatial discontinuity of a bed boundary.
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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) | 1995-03-10 | 1995-09-09 | 1996-03-10 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1999-03-10 | 1999-09-09 | 2000-03-10 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2003-03-10 | 2003-09-09 | 2004-03-10 | $7700.00 | Window Closed / Lapsed |