A Three-level Calibration Method for DC Weak Signal of Formation Water Resistivity Logging Tool

Abstract

The invention discloses a three-level calibration method for DC weak signals of a formation water resistivity logging instrument, which is characterized in that it includes instrument-level calibration, channel-level calibration and real-time period-level calibration; the instrument-level calibration is an instrument using an analog box calibration The constant DC power supply, the performance of the entire analog channel and the function of the digital channel; the channel-level scale is the use of a scale device to scale the performance of the entire analog channel and the function of the digital channel; the real-time cycle-level scale is transmitted through the DAC according to a predetermined timing A series of fixed positive and negative voltage values, control the scale relay to send the signal to the measurement channel, amplify and process through n different pre-amplification channels, and then after multi-channel gating switching and filtering, the ADC will collect according to the preset timing . The invention improves the accuracy of the formation water resistivity logging instrument for signal measurement and collection, and also improves the adaptability of the instrument to different well conditions.

Description

technical field [0001] The invention belongs to the technical field of petroleum well logging, and in particular relates to a three-level calibration method for DC weak signals of a formation water resistivity logging instrument, which is used for daily maintenance and detection of the instrument and real-time compensation of the instrument during the well logging process. Background technique [0002] In the field of domestic logging instruments, most self-emission logging instruments emit AC sine wave signals, while formation water resistivity logging instruments emit DC signals. The weak AC signal can be easily restored to the original measurement signal after amplification, filtering, acquisition and processing. At present, the AC signal in the logging instrument can realize the effective resolution and measurement acquisition of 100nV level or even smaller signals, while the weak DC signal is limited. Due to the power noise of the downhole system, the ground noise of th...

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Problems solved by technology

[0003] The purpose of the present invention is to provide a three-level calibration method for DC weak signals of the formation water resistivity logging instrument, so as to overcome the weak and small DC signal and the vulnerability of the logging signal fluctuations in the logging process of the existing formation water resistivity logging instrument The shortcoming of influence, the present invention improves formation water resistivity logging tool for the accuracy of signal measurement acquisition, plays a key role for the accurate measurement of formation water resistivity logging tool signal, also improves the automaticity of different well conditions of instrument adaptability

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