Study On Waveform Inversion Method Of Microseismic Source Parameters

Hydraulic fracturing,as the key technology of exploiting tight oil and gas reservoir,can effectively improve oil and gas production rate.In the process of hydraulic fracturing,the fracturing effect can be evaluated by microseismic monitoring,and in the process of microseismic monitoring,it is mainly to monitor the source of microseismic,therefore,the inversion of microseismic source can effectively evaluate the fracturing effect in the process of production,which is of great significance for oil and gas production.In microseismic source inversion,travel time information is easily affected by low signal-to-noise ratio microseismic records,but waveform information is less affected by low signal-to-noise ratio.In this paper,there are two methods for inversion of microseismic source parameters based on waveform information.The first method is wave field inverse time-delay extension method,the imaging conditions and the positioning method of the elastic medium are studied respectively,according to the characteristics of the existing imaging conditions,an optimized imaging condition is proposed and kurtosis value is used as the evaluation standard,In the inverse time localization of elastic wave,the elastic wave field in the process of back propagation is decoupled,and the localization effect before and after decoupling is compared and analyzed,and the imaging focus function is introduced to improve the imaging resolution;The second method is full waveform inversion of microseismic source parameters,on the basis of inverse time location,the source parameters can be obtained by full waveform inversion,in the process of research,according to the characteristics of microseismic source,a spectral projection gradient inversion method based on group sparsity constraint is proposed,which can effectively inverse the temporal and spatial information of the source.The results show that,In the process of acoustic inverse time positioning,according to kurtosis value as the evaluation standard,the optimized imaging conditions can effectively improve the positioning imaging resolution;In the process of elastic wave inverse time positioning,the result of decoupled back propagation field is better than that of uncoupled back propagation field,and the resolution of imaging result can be further improved by using imaging focus function;In the process of full waveform inversion of source parameters,the proposed group sparse constrained spectral projection gradient inversion can effectively adapt to the source characteristics of microseismic,and can better inverse the source position information,wavelet information,and can help update the velocity model.