Research On Acquisition And Data Processing Of Seismic Electric Signal While Drilling

Energy is an important driving force for economic development.Countries have been committed to research and development of scientific and effective energy exploration and mining equipment.Since the discovery of the seismoelectric effect,countries have conducted in-depth research on its principles and applications.Among them,the application of seismoelectric effects in the field of logging while drilling,especially in the search for petroleum,has become a research hotspot.Compared with the traditional logging-while-drilling technology,the seismic-electric effect provides a new research direction in the field of logging.And experiments prove that the seismic electricity effect has great potential in oil and water resources exploration and exploitation.When an elastic wave propagates in a porous medium,it will excite a seismic electrical signal at the solid-liquid interface.Seismic signals can analyze formation geological characteristics.Based on this principle,a signal acquisition and processing system for seismic logging while drilling is proposed.This is mainly divided into five parts: acquisition system,communication system,host computer software,wavelet threshold denoising,and slow time-related algorithms.The acquisition system and communication system use FPGA as the core chip and carry other peripherals,which are mainly used to realize the functions of acquisition,processing,storage,and transmission of seismic signals.In this system,there are eight acquisition boards,which constitute eight independent acquisition channels.After the trigger signal is triggered,the eight acquisition boards simultaneously perform operations such as acquisition,filtering,and storage of seismic signals.There is only one communication board.By continuously detecting the status of eight acquisition boards,the sampling data stored on the acquisition boards is uploaded to the PC in a time-sharing manner.The inter-board communication method between the acquisition board and the communication board uses the SPI protocol.The communication method between the communication board and the PC uses serial communication.The host computer is located on a PC and is written in C #.Mainly can achieve serial port reception,accumulation average,waveform display,data storage and other functions.The original data of the seismoelectric signal saved by the host computer needs to be threshold denoised by wavelet transform method,and then the slow time correlation algorithm is performed.Through this algorithm,the wave velocity of each mode in the seismic signal can be analyzed.The wave velocity reflects the formation parameters,such as porosity and permeability.The system has undergone joint testing of software and hardware.The experimental results show that the circuit system can complete the collection,processing,and transmission of weak seismic electrical signals,and the host computer runs stably,and can realize functions such as serial port reception,waveform display,and cumulative averaging.Through the test and analysis of laboratory porous rock samples,the results are good,the wave velocity of the seismic signal can be extracted,and it can be applied to real wells for field testing.