Compensated Tri-Axial Propagation Measurements
US-2015276967-A1 · Oct 1, 2015 · US
Gain compensated directional propagation measurements
US9448324B2 · US · B2
| Field | Value |
|---|---|
| Publication number | US-9448324-B2 |
| Application number | US-201414325797-A |
| Country | US |
| Kind code | B2 |
| Filing date | Jul 8, 2014 |
| Priority date | Mar 29, 2014 |
| Publication date | Sep 20, 2016 |
| Grant date | Sep 20, 2016 |
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Abstract
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A method for obtaining gain compensated electromagnetic logging while drilling propagation measurements includes rotating an electromagnetic logging while drilling tool having first and second transverse transmitter antennas whose moments are orthogonal to one another and first and second transverse receiver antennas whose moments are orthogonal to one another in a subterranean wellbore. Electromagnetic voltage measurements are acquired from the first and second transverse receiver antennas while rotating. The acquired voltage measurements are processed to compute harmonic voltage coefficients. Ratios of selected ones of the harmonic voltage coefficients are in turn processed to compute a gain compensated quantity including a transverse term.
First claim
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What is claimed is: 1. A method for making downhole electromagnetic logging while drilling measurements, the method comprising (a) rotating an electromagnetic logging while drilling tool in a subterranean wellbore, the logging tool including first and second transverse transmitter antennas whose moments are orthogonal to one another and first and second transverse receiver antennas whose moments are orthogonal to one another; (b) acquiring a plurality of electromagnetic voltage measurements from the first and second transverse receiver antennas while rotating in (a); (c) processing the voltage measurements acquired in (b) to compute harmonic voltage coefficients; (d) processing a ratio of the harmonic voltage coefficients to compute a gain compensated quantity including a transverse term, wherein the transverse term is one an xx direct coupling impedance, a yy direct coupling impedance, an xy cross coupling impedance and yx cross coupling impedance or a combination thereof. 2. The method of claim 1 , wherein the processing in (d) is performed by a downhole processor. 3. The method of claim 2 , further comprising: (e) transmitting the gain compensated quantity to a surface location; and (f) causing a surface computer to invert the gain compensated quantity to obtain one or more properties of a subterranean formation. 4. The method of claim 1 , further comprising: (e) processing the gain compensated quantity to compute a gain compensated phase shift and a gain compensated attenuation. 5. The method of claim 1 , wherein the harmonic voltage coefficients computed in (c) comprise DC, first order harmonic sine, first order harmonic cosine, second order harmonic sine, and second order harmonic cosine voltage coefficients. 6. The method of claim 1 , wherein the gain compensated quantity computed in (d) comprises at least one proportional to an xx coupling or a yy coupling. 7. The method of claim 6 , wherein the gain compensated quantity is computed using at least one of the following mathematical equations: CXX xx = ( V D C _ 12 xx + V SHC _ 12 xx ) ( V D C _ 21 xx + V SHC _ 21 xx ) ( V D C_ 11 xx + V SHC _ 11 xx ) ( V D C _ 22 xx +
Assignees
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Classifications
using induction coils · CPC title
specially adapted for well-logging · CPC title
operating with electromagnetic waves · CPC title
using several coupled or uncoupled coils (G01V3/101 takes precedence) · CPC title
- G01V3/38Primary
Processing data, e.g. for analysis, for interpretation, for correction · CPC title
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- What does patent US9448324B2 cover?
- A method for obtaining gain compensated electromagnetic logging while drilling propagation measurements includes rotating an electromagnetic logging while drilling tool having first and second transverse transmitter antennas whose moments are orthogonal to one another and first and second transverse receiver antennas whose moments are orthogonal to one another in a subterranean wellbore. Electr…
- Who is the assignee on this patent?
- Schlumberger Technology Corp
- What technology area does this patent fall under?
- Primary CPC classification G01V3/38. Mapped technology areas include Physics.
- When was this patent published?
- Publication date Tue Sep 20 2016 00:00:00 GMT+0000 (Coordinated Universal Time) (B2). Legal status and post-grant events are not shown on this page.
- What related patents are in patentsdb?
- We list 4 related publications on this page (citations in our corpus or others sharing the same primary CPC).