US 12,222,461 B2
Antenna calibration in an EM logging tool
Kong Hauw Sarwa Bakti Tan, Sugar Land, TX (US); Qingyan He, Pearland, TX (US); Qing Zhang, Sugar Land, TX (US); Desheng Zhang, Sugar Land, TX (US); Kent Harms, Richmond, TX (US); and Daniel Fernandez, Sugar Land, TX (US)
Assigned to Schlumberger Technology Corporation, Sugar Land, TX (US)
Appl. No. 17/999,067
Filed by Schlumberger Technology Corporation, Sugar Land, TX (US)
PCT Filed Jun. 21, 2021, PCT No. PCT/US2021/038233
§ 371(c)(1), (2) Date Nov. 17, 2022,
PCT Pub. No. WO2021/258047, PCT Pub. Date Dec. 13, 2021.
Claims priority of provisional application 62/705,271, filed on Jun. 19, 2020.
Prior Publication US 2023/0184991 A1, Jun. 15, 2023
Int. Cl. G01V 13/00 (2006.01); G01V 3/28 (2006.01); H01Q 1/04 (2006.01)
CPC G01V 13/00 (2013.01) [G01V 3/28 (2013.01); H01Q 1/04 (2013.01)] 19 Claims
OG exemplary drawing
 
1. 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.