Underground magnetic field detection while drilling device

Abstract

The invention provides an underground magnetic field detection while drilling device. The device outputs PWM signals to a fluxgate drive circuit through a DSP and controls an FPGA to synchronously sample waveform data, the fluxgate drive circuit excites a fluxgate sensor to sense X-axis, Y-axis and Z-axis magnetic fluxes and converts the magnetic fluxes into voltage signals, a voltage signal sequentially passes through a band-pass filter, a gain circuit and a first analog-to-digital converter and is converted into sampling waveform data to be stored in the FPGA, the DSP reads the sampling waveform data in the FPGA, digital band-pass filtering is carried out on the sampling waveform data, digital phase-sensitive detection is carried out on a filtering signal obtained through digital band-pass filtering, the sampling waveform data are stored in the FPGA, digital integration is carried out on waveform data obtained after digital phase-sensitive detection, digital low-pass filtering and amplitude extraction are carried out on the waveform data obtained after digital integration to obtain the magnetic field intensity, the magnetic field intensity is sent to a central control communication circuit, and detection while drilling of the magnetic field intensity in an underground complex environment is achieved.

Description

technical field

[0001] The invention relates to the technical field of drilling and exploration engineering, in particular to an underground magnetic field detection device while drilling. Background technique

[0002] During the drilling process, the metal substances around the well drilling (for example, the ferromagnetic casing in the well drilling) will generate a magnetized magnetic field, which will cause geomagnetic anomalies near the metal substances, and the detection of geomagnetic anomalies during drilling can be positive. Provide technical support for the distance and orientation of metal substances near the drilling location.

[0003] In the prior art, the method of collecting magnetic signals is to use a fluxgate to convert the external magnetic field into a voltage signal containing a second harmonic through a high-frequency drive circuit. The amplitude of the second harmonic is related to the strength of the external magnetic field, and then filtered The cir...

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