US 12,222,461 B2Granted

Antenna calibration in an EM logging tool

AssigneeSchlumberger Technology Corporation

InventorsKong Hauw Sarwa Bakti Tan, Qingyan He, Qing Zhang, Desheng Zhang, Kent Harms, Daniel Fernandez

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Abstract

A method for calibrating an electromagnetic measurement tool includes deploying a test loop about a first antenna in the electromagnetic measurement tool and electromagnetically coupling the test loop and the first antenna and measuring a first voltage. The test loop is then deploying about a second antenna in the electromagnetic measurement tool and electromagnetic ally coupling the test loop and the second antenna and measuring a second voltage. A ratio of the first voltage to the second voltages is computed that can be used to calibrate the first antenna with respect to the second antenna.

Claims19

Dependent claims

A method of calibrating an electromagnetic measurement tool, the method comprising:

(a) deploying a test loop about a first antenna in the electromagnetic measurement tool;
(b) electromagnetically coupling the test loop and the first antenna;
(c) measuring a first voltage in the first antenna or in the test loop induced by the electromagnetically coupling the test loop and the first antenna;
(d) deploying the test loop about a second antenna in the electromagnetic measurement tool;
(e) electromagnetically coupling the test loop and the second antenna;
(f) measuring a second voltage in the second antenna or in the test loop induced by the electromagnetically coupling the test loop and the second antenna;
(g) computing a ratio of the first voltage to the second voltage;
and
(h) calibrating electromagnetic measurements made with the first antenna to electromagnetic measurements made with the second antenna using the computed ratio, wherein calibrating the electromagnetic measurements comprises:
(h1) storing the ratio to memory in the electromagnetic measurement tool;
(h2) deploying the electromagnetic measurement tool in a subterranean wellbore;
(h3) causing the electromagnetic measurement tool to make first electromagnetic measurements with the first antenna and second electromagnetic measurements with the second antenna while deployed in the wellbore;
and
(h4) multiplying the first electromagnetic measurements by the ratio to obtain calibrated first electromagnetic measurements.

11 more elements

A method of calibrating an electromagnetic measurement tool, the method comprising:

(a) deploying a test loop about a first antenna in the electromagnetic measurement tool;
(b) electromagnetically coupling the test loop and the first antenna, wherein electromagnetically coupling the test loop and the first antenna comprises applying a first alternating electric current to (i) the test loop or the first antenna and to (ii) a normalizing resistor that is in series with the test loop or the first antenna;
(c) measuring a first voltage in the first antenna or in the test loop induced by the electromagnetically coupling the test loop and the first antenna, wherein measuring the first voltage comprises measuring a first resistor voltage in the normalizing resistor caused by the applying the first alternating electric current to the normalizing resistor;
(d) deploying the test loop about a second antenna in the electromagnetic measurement tool;
(e) electromagnetically coupling the test loop and the second antenna, wherein electromagnetically coupling the test loop and second first antenna comprises applying a second alternating electric current to (i) the test loop or the second antenna and (ii) the normalizing resistor that is in series with the test loop or the second antenna;
(f) measuring a second voltage in the second antenna or in the test loop induced by the electromagnetically coupling the test loop and the second antenna, wherein measuring the second voltage comprises measuring a second resistor voltage in the normalizing resistor caused by the applying the second alternating electric current to the normalizing resistor;
and
(g) computing a ratio of the first voltage to the second voltage, wherein the ratio computed in (g) is a product of first, second, and third ratios, the first ratio being a ratio of the first voltage to the second voltage, the second ratio being a ratio of the second resistor voltage to the first resistor voltage, and the third ratio being a ratio of a function of a tilt angle of the first antenna and the function of a tilt angle of the second antenna.

5 more elements

Dependencies are inferred from the claim text.

Facts

Application: 17/999,067Filed 21 Jun 2021 · us provisional application
Priority: 19 Jun 2020
Published: US 2023/0184991 A115 Jun 2023
Granted: 11 Feb 2025
Term ends: Not estimatedThe source records don’t support an estimate.

Classification7 codes

G01V 13/00
Manufacturing, calibrating, cleaning, or repairing instruments or devices covered by groups g01v1/00
G01R 35/00
Testing or calibrating of apparatus covered by the other groups of this
G01V 3/28
Operating with magnetic or electric fields produced or modified either by the surrounding earth formation or by the detecting device: using…
H01Q 1/04
Details of, or arrangements associated with, antennas: adaptation for subterranean or subaqueous use

Family

Application62/705,271Us provisional application · filed 19 Jun 2020
US 2023/0184991 A1Pre-grant publication · published 15 Jun 2023
US 12,222,461 B2This patent

From the US filing history. Foreign family members aren’t listed.

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