Series acoustic wave storage variable density logging unit

Abstract

The invention relates to an oil field underground logging unit, in particular to a series acoustic wave storage variable density logging unit. The logging unit is characterized in that the logging unit comprises at least a group of upper acoustic detection units (1), a group of lower acoustic detection units (2), a magnetic positioning unit (3) and a detection processing unit (4); the detection processing unit (4) is respectively electrically connected with emission control ports of the upper acoustic detection units (1) and the lower acoustic detection units (2) through I / O interfaces; acoustic detection circuits of the upper acoustic detection units (1) and the lower acoustic detection units (2) transmit the detected signals to an amplification processing circuit, the digital signals converted by the amplification processing circuit are transmitted to the I / O interface of the detection processing unit (4), and the detection processing unit (4) stores the processed signals on a memory card (5). The transmission error of acoustic signals caused by the poor frequency characteristic of direct-read type cable in prior arts is avoided, and thus the measuring curve resolution and the precision are improved.

Description

technical field [0001] The invention relates to an oil field downhole acoustic wave logging instrument, in particular to a series of stored acoustic wave variable density logging instruments. Background technique [0002] The storage acoustic logging tool is the first product of our company in China. Based on the functions of the original direct-reading acoustic amplitude logging tool, it realizes two working modes of storage and direct reading of downhole acoustic logging data. [0003] The conventional single-engine double-receiver direct-reading acoustic variable density logging tool is used to detect the cement bond quality of cased wells. The instrument measures four parameters: casing collar (CCL for short), natural gamma ray (GR for short), sound amplitude (CBL for short ), variable density (VDL for short), the casing collar measures the connection point of two casings downhole, the measurement principle is that when the probe passes through the collar, the fixed magn...

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Problems solved by technology

[0004] In terms of structure, in addition to the above-mentioned single-engine and double-receipt methods, there are also single-engine and four-receive methods, double-engine and double-receive methods, and double-engine and eight-receive methods in conventional acoustic logging tools. processing and transmission, which have technically insurmountable shortcomings in conventional non-storage acoustic logging tools

[0005] The frequency of the acoustic signal used by the conventional direct-reading acoustic logging tool is generally 20KHZ, and the acoustic signal transmission adopts a single-core cable or a multi-core cable. The response frequency of the conventional cable is only a dozen KHZ, so when the acoustic signal is transmitted to the ground There will be distortion, which will cause errors in the measurement resolution and accuracy of the instrument, and the transmission errors of the acoustic signal for different types of cables with different lengths are different, so this measurement error is unavoidable in the application of traditional acoustic wave variable density logging tools of

[0006] To solve this problem, the current technical method is to convert the acoustic signal through underground analog-to-digital conversion, and use digital signal for high-speed remote transmission. The cost of hardware equipment and cost is very high; another method is to replace it with a special cable that meets the transmission frequency characteristics. , its price is several times that of conventional circuits, which is very expensive and not conducive to field promotion

[0007] However, in horizontal wells, highly deviated wells and other well conditions where the cable cannot lower the instrument, the conventional acoustic amplitude variable density instrument cannot realize its logging function, and there is an urgent need for a battery-powered logging instrument.

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