US-12618321-B2 - Calibration method for logging-while-drilling device

US12618321B2US 12618321 B2US12618321 B2US 12618321B2US-12618321-B2

Abstract

The present application discloses a calibration method for a logging-while-drilling device, which is used for measuring data on the sea level and comprises the following steps: horizontally suspending the logging-while-drilling device; measuring amplitudes and phases at different heights; horizontally rotating the logging-while-drilling device for multiple times, and measuring amplitudes and phases at different heights after each horizontal rotation; and when the sum of angles of the multiple horizontal rotations is greater than 360 degrees, calculating an azimuth correction factor according to the measured amplitudes and phases. As the calibration method for the logging-while-drilling device according to the present application is carried out on a wide seawater interface, the influence of the boundary effect can be eliminated; the uniform medium attributes of air and seawater can be simplified into a one-dimensional double-layer medium model.

Inventors

Xinghan LI
Wenxiu ZHANG
Wenxuan CHEN
Jian Zheng
Wenqiang YUAN
Yali Zhang
Hong Li

Assignees

INSTITUTE OF GEOLOGY AND GEOPHYSICS, CHINESE ACADEMY OF SCIENCES

Dates

Publication Date: 20260505
Application Date: 20230208
Priority Date: 20220601

Claims (4)

1 . A calibration method of a logging while drilling device, wherein measurement data is taken beginning at sea level, and the calibration method comprises: the logging while drilling device comprises a first transmitter, a second transmitter, a third transmitter, a fourth transmitter, a first receiver and a second receiver; the first transmitter, the second transmitter, the third transmitter and the fourth transmitter are sequentially arranged on the logging while drilling device in a well-entering direction; the first receiver is arranged between the first transmitter and the second transmitter, and the first receiver is configured to receive signals transmitted by the third transmitter and the fourth transmitter; the second receiver is arranged between the third transmitter and the fourth transmitter, and the second receiver is configured to receive signals transmitted by the first transmitter and the second transmitter; and suspending the logging while drilling device horizontally; and the logging while drilling device measures amplitudes and phases at different heights; the amplitudes and phases measured comprise: sequentially measuring the amplitudes and phases of signals transmitted by the first emitter, the fourth emitter, the second emitter and the third emitter by using the logging while drilling; the logging while drilling device measures both in the initial floating position and after being rotated position; rotating the logging while drilling device multiple times horizontally, and measuring amplitudes and phases at different heights after each horizontal rotation; when the sum of the angles of multiple horizontal rotations is greater than 360 degrees, and a azimuth correction factor is calculated according to the amplitudes and phases; and the amplitudes and phases measured at different heights comprise: the amplitudes and phases measured once every 0.5 m between 1.5 and 8 m above sea level to obtain first measurement results; the amplitudes and phases measured once every 0.3 m between 0.3 and 1.5 m above sea level to obtain second measurement results; the first measurement results and the second measurement results are first data; a plurality of the first data are converted into real parts and imaginary parts, and a phase shift factor and an amplitude reduction factor are calculated through the real parts and the imaginary parts.
2 . The calibration method according to claim 1 , wherein the first transmitter, the second transmitter, the third transmitter and the fourth transmitter transmit signals of 0.4 MHz for the first receiver and 2 MHz for the second receiver to receive signals.
3 . The calibration method according to claim 1 , wherein the angle of horizontal rotation is 45 degrees.
4 . The calibration method according to claim 1 , wherein four sets of data are measured for each height.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS This application is a bypass continuation application of PCT application no.: PCT/CN2019/097583. This application claims priorities from PCT Application PCT/CN2019/097583, filed Jul. 24, 2019, and from Chinese patent application 202210621327.5, filed on Jun. 1, 2022, the contents of which are incorporated herein in the entirety by reference. TECHNICAL FIELD The present disclosure relates to the field of structure detection technologies, and in particular, to a calibration method for a logging-while-drilling device. BACKGROUND ART An azimuthal electromagnetic wave resistivity logging-while-drilling tool possesses a capability of detecting the stratigraphic boundary by adding inclined or horizontal antennas. The stratigraphic information at different depths can be detected in combination with characteristics of multiple frequencies and multiple receiver-to-transmitter spaces (Wang, 2007). Currently. Schlumberger achieves azimuth detection by using a remote inclined antenna for receiving, with the signal transmission frequencies being 2 MHz, 400 KHz and 100 kHz (Li et al., 2005; Omeragic et al., 2005); Halliburton achieves azimuth detection by three inclined receiver coils, with the signal transmission frequencies being 2 MHZ, 500k Hz and 125 kHz (Bittar et al., 2009); and Baker Hughes achieves azimuth detection by a set of horizontal antennas, with the signal transmission frequencies being 400 kHz and 2 MHz (Wang, 2006; Meyer et al., 2008). The horizontal antenna structure adopted by Baker Hughes avoids the effect of directly-coupling signals, such that signals received by the azimuth antenna can fully reflect the stratigraphic boundary information. For traditional methods, the calibration is implemented by a water tank. However, the radius of the water tank is limited, and the calibration with the water tank is affected by the edge effect, which greatly attenuates the azimuth signal. Further, the model is complex, and the measurement environment can hardly be fully recovered, which seriously suppresses the calibration results, causes errors to the azimuth signal, and thus leads to deviations in the final backward modeling results. SUMMARY An object of the present disclosure is to provide a calibration method for a logging-while-drilling device to solve the technical problem in the prior art that a calibration method using a water tank has larger errors. To solve the above problem, the present disclosure provides a calibration method for a logging-while-drilling device, which is used for measuring data on the sea level and includes the following steps: horizontally suspending the logging-while-drilling device; measuring amplitudes and phases at different heights; horizontally rotating the logging-while-drilling device for multiple times, and measuring amplitudes and phases at different heights after each horizontal rotation; and when the sum of angles of the multiple horizontal rotations is greater than 360 degrees, calculating an azimuth correction factor according to the measured amplitudes and phases. As the calibration method for the logging-while-drilling device according to the present disclosure is carried out on a wide seawater interface, the influence of the boundary effect can be eliminated; the uniform medium attributes of air and seawater can be simplified into a one-dimensional double-layer medium model, and meanwhile, the air-seawater environment ensures the consistency between a forward modeling model and an actual measurement environment; and the high air-seawater conductivity contrast can enhance the azimuth signal intensity. In addition, through multi-angle measurement at different heights, the calibration accuracy can be greatly improved. BRIEF DESCRIPTION OF THE DRAWINGS One or more embodiments are exemplarily described by a figure in the corresponding accompanying drawings. Unless otherwise specified, the figures in the accompanying drawings do not constitute a scale limitation. FIG. 1 is a flowchart for a calibration method for a logging-while-drilling device according to an embodiment of the present disclosure; FIG. 2 is a calibration state diagram for a calibration method for a logging-while-drilling device according to an embodiment of the present disclosure; FIG. 3 is a schematic diagram for a logging-while-drilling device according to an embodiment of the present disclosure; FIG. 4 is a schematic diagram for a logging-while-drilling device according to another embodiment of the present disclosure; FIGS. 5A-5B are signal trend diagrams for water tanks with different radiuses in a calibration method for a logging-while-drilling device according to the prior art; and FIGS. 6A-6D are signal trend diagrams of a calibration method for a logging-while-drilling device according to another embodiment of the present disclosure. In FIG. 2. dashed lines indicate the sea level. In FIG. 3, T1 refers to a first transmitter;T2 refers to a second transmitter;T