The Analysis Of Wave Filed Separation Of Microsismic Singal

The technology of microseismic monitoring is geophysical technology which used of monitoring the waves of the rock producing fractures to obtain the distribution of fractures, the flow of fluid and the trend of stress. It has been widely used in petroleum engineering, environmental and public safety, mining engineering, civil engineering and other fields. In the oil and gas field, The technology of microseismic monitoring is monitoring technology which determining the microseismic source location by microseismic signals that produced the fractured rock when hydraulic fracturing, oil and gas recovery or conventional water injection, gas injection, thermal driving oil and petroleum engineering work, lead to changes of underground stress field, It is different seismic signals obtained with the signals of conventional seismic exploration microseismic source location, origin time and the source strength is unknown, These factors determine precisely the primary task of technology of microseismic monitoring.This technology has unique advantages in judgment fracturing effect, adjust hydraulic fracturing plan and other aspects,it’s a effective mean to improve the effectiveness of unconventional reservoir development. The theoretical basis of technology of microseismic monitoring is acoustic emission and seismology. The study of key technology includes data acquisition, signal processing, automatic picking of microseismic events, focal imaging and fine inversion. The technology started lately in China, With the advent of unconventional oil and gas fields of the key technologies of high-yielding (horizontal drilling and fracturing reservoir stimulation)。The technology has been rapid development, but There is still a considerable distance to meet our requirements.This paper explains the formation mechanism of microseismic, introduces the development process of microseismic monitoring technology, the acquisition methods of microseismic monitoring data and the integral part of microseismic monitoring system;Discusses the particle vibration mode of the microseismic phases, micro-seismic signals and interference characteristics, preprocessing methods of microseismic signal:inclination and azimuth correction, spectral analysis, frequency filtering, channel equalization, median filtering;and Describes the polarization filtering, fk filtering, prediction filtering and other separation method of microseismic wave.Application matlab language of inclination and azimuth correction, frequency filtering, channel equalization, principal component analysis, polarization filtering, fk filtering, prediction filtering and other programs processes the data of microseismic cllested on the site. The results showed that:(1)frequency filtering and principal component analysis has little good effect on picking the beginning time of the P wave.(2) The effect of prediction filtering in time domain is better, P wave and S wave can be clearly shown, the filter have a depressing effect on multiple waves and guide wave, the effect of prediction filter in Radon domain is worse than the effect of prediction filter in time domain, because of the data of microseismic event missing the distance information of source to detector, so the Radon transform is limited.(3)The polarization filter can be used to distinguish linearly polarized waves and nonlinear polarization wave, but the requirements of polarization filter is microseismic signals with high signal to noise ratio;(4) By attenuating noise to highlight P-wave and S-wave in micro-seismic events is convenient to real-time imaging for fractures, if the P-wave and S-wave is separated into two records, from a program perspective is inconvenient;(5) The core issues of real-time monitoring of microseismic signal is automatically detected, because the origin time is unknown, determining the microseismic source location in real time to time by the beginning time of the P wave may affect the accuracy of fractures imaging;If the beginning time of P wave as the time of microseismic occurred, the beginning time of S-wave is used for determining the microseismic source location in real time to time, the ability to improve the accuracy of imaging fractures need model validation, The application conditions of this idea is that S waves is shown in microseismic events, if S wave does not exist or is severely attenuated, this idea will lose its significance.