Automatic positioning and interpreting instrument and method adopting natural gamma rays of formations and used for down-hole strings

Abstract

The invention relates to an automatic positioning and interpreting instrument and method adopting natural gamma rays of formations and used for down-hole strings, and mainly solves the problem of large depth measuring error during test of a conventional magnetic locator. The automatic positioning and interpreting instrument is characterized in that a magnetic positioning tester (2) and a gamma ray curve tester (3) are connected to the lower part of an upper joint (1) sequentially, a centralizer (4) is connected to the bottom of the gamma ray curve tester (3), a weight bar (5) is connected to the bottom of the centralizer (4), a steel wire rope is connected to the upper part of the upper joint (1) and is connected to a double-drum winch (7) after bypassing a top sheave (6). Errors caused by cable stretching can be avoided when the instrument is adopted to measure the depth, cable depth correction is not required, and a result is more accurate.

Description

technical field [0001] The invention relates to the field of oil fields, in particular to an automatic positioning and interpretation instrument and method for downhole pipe strings using formation natural gamma ray. Background technique [0002] In the oil field testing technology, the armored wire cable is run into the magnetic locator for testing. During the downhole positioning process, the magnetic positioning curve is obtained by inducing the change of the magnetic flux. However, due to the elastic stretch of the cable and the use of a professional test vehicle, it has its limitations, and the test cost is high, so it cannot be tested in a large area. Among them, the cable will stretch more than 1,000 meters underground due to gravity, which will cause errors in the depth measurement. In order to reduce this stretching error, it is necessary to correct the test results. The current correction method is to use cable marks. Depth calibration, that is, to reduce this err...

AI Technical Summary

Problems solved by technology

However, due to the elastic stretch of the cable and the use of a professional test vehicle, it has its limitations, and the test cost is high, so it cannot be tested in a large area.

Among them, the cable will stretch more than 1,000 meters underground due to gravity, which will cause errors in the depth measurement. In order to reduce this stretching error, it is necessary to correct the test results. The current correction method is to use cable marks. Depth calibration, that is, to reduce this error by marking the corresponding depth on the cable through the standard depth well. This method corrects the elastic error through the position-elongation coefficient, and cannot completely avoid the elastic error, so the measurement error cannot be completely eliminated.

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