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Correcting method of skin effect of induction log

A skin effect and induction logging technology, which is applied in the direction of measuring devices, earthwork drilling, borehole/well components, etc., can solve the problems of increasing the cost of induction logging instruments, and achieve the effect of improving error and accuracy

Inactive Publication Date: 2015-04-29
CNPC GREATWALL DRILLING ENG
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, in order to use the invention described in U.S. Patent No. 5,666,057 in practice, a series of in-phase component measurements are required to obtain a simple and practical spectrum, which greatly increases the cost of the induction logging tool

Method used

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  • Correcting method of skin effect of induction log
  • Correcting method of skin effect of induction log
  • Correcting method of skin effect of induction log

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Experimental program
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Embodiment Construction

[0045] The invention only uses the measured value of the in-phase signal to effectively correct the change of the apparent conductivity value and the geometric factor caused by the skin effect in the induction well logging.

[0046] In a simple isotropic formation, its conductivity is σ, then the induced signal value when there are only two coils can be expressed as:

[0047] ......(1)

[0048] ......(2)

[0049] in,

[0050] ω is the angular frequency;

[0051] mu is the magnetic permeability;

[0052] N T with N R are the turns of the transmitting coil and receiving coil, respectively;

[0053] S T with S R are the cross-sectional areas of the transmitting coil and receiving coil, respectively;

[0054] I T is the current intensity of the transmitting coil;

[0055] L is the distance between the transmitting coil and the receiving coil;

[0056] usually, p called the propagation cons...

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Abstract

The invention relates to a correcting method of the skin effect of an induction log. The correcting method adopts a measured value of an inphase signal to correct an apparent electrical conductivity value and the changes of geometric factors of electrical conductivity, caused by the skin effect of the induction log; wherein mathematical modeling and polynomial approximation are performed on the skin effect so as to construct a mathematical expression of the skin effect; further approximation and calculation are performed so as to determine the final electrical conductivity value and the final geometric factors of the electrical conductivity, which are corrected by the skin effect; and therefore, an error caused by the skin effect in a process of the induction log in the prior art is greatly improved, and besides, the accuracy of the geometric factors is improved.

Description

technical field [0001] The invention belongs to the field of induction logging, and relates to a method for correcting the skin effect that affects the measurement signal during the measurement process using an electromagnetic induction logging instrument. Background technique [0002] Well logging is the use of downhole instruments to perform various measurements on downhole formations in different ways. as attached figure 1 As shown, in the process of well logging operation, the downhole instrument is first lowered into the borehole; secondly, the surface system provides the downhole instrument with the power required for the well logging operation and sends commands to the downhole instrument through the cable and telemetry system; then, the downhole instrument Various formation data are collected during lifting or lowering, and these data are transmitted to the ground through the cable remote transmission system, and the ground system records, displays, analyzes and pro...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): E21B49/00G01V13/00
CPCE21B49/00G01V3/38
Inventor 肖加奇
Owner CNPC GREATWALL DRILLING ENG
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