Inversion Positioning Method Of Hydraulic Fracturing Microseismic Events

For the exploration and development of unconventional oil and gas reservoirs,microseismic monitoring technology is an effective method to quantitatively analyze the development of fractures in the process of hydraulic fracturing reservoir reconstruction.At present,as major oil and gas companies at home and abroad pay more attention to the development of unconventional oil and gas resources,microseismic monitoring technology has developed rapidly and its application prospects have become more and more extensive.Therefore,this paper conducts research work on the numerical simulation method of micro-seismic monitoring,starting from the forward simulation of micro-seismic data,carrying out a series of finite difference method forward simulation of micro-seismic data,the first arrival of micro-seismic events,the inversion and positioning of micro-seismic events,etc.Applied research on technical methods.The details are as follows:(1)Forward simulation of microseismic data.In this paper,the regular grid and staggered grid finite difference methods are used to solve the acoustic and elastic wave equations,and the forward simulation of 2D and 3D microseismic data is completed.At the same time,the PML absorption boundary condition is used to absorb and attenuate the model boundary reflection,and the model test is performed.(2)Loading and forward simulation of different focal mechanisms.Due to the complex causes of acoustic emission caused by hydraulic fracturing and the various forms of source rupture,the source mechanism was introduced in the forward modeling,and the 3D microseismic data based on three common source mechanisms(ISO,CLVD,DC)were completed.Simulation,recording the seismic records simulated by the three focal mechanisms,and the snapshots of wave fields at different times,provides a theoretical basis and data preparation for microseismic focal location.(3)The first arrival of the micro-earthquake event.For the microseismic positioning method based on the travel time objective function,the accuracy of the first arrival of the microseismic event directly affects the accuracy of its positioning result.Therefore,while demonstrating the feasibility of picking the first arrival of micro-seismic events with the energy ratio method of long and short time windows,the statistical energy ratio method of transforming time windows is implemented,and the noise resistance of the method is analyzed,and an improved method with strong noise resistance is proposed.,And applied to different noise data for method testing.(4)Micro seismic event inversion positioning.The simulation realizes the microseismic source positioning algorithm of triangulation,Geiger,grid search.Calculate the 2D and 3D microseismic data models,and analyze the error of the calculation results.