Research On Microseismic Monitoring Technology Of Horizontal Well Fracturing

Ordos Basin is a typical unconventional oil and gas resource accumulation area in China.It has the characteristics of low porosity and permeability,complex pore structure,poor continuity and strong heterogeneity.It is necessary to use hydraulic fracturing technology to expand oil and gas seepage channels,maximize the control of fracture network of single well reserves,monitor the dynamic changes of fracturing fractures in real time in combination with in well microseismic monitoring technology,and evaluate the effects of fracturing construction and reservoir reconstruction,Guide well pattern deployment and optimize hydraulic fracturing injection production process.In this paper,by studying the acquisition method of micro seismic data in wells and the propagation characteristics of micro seismic events,the micro seismic data are preprocessed,and the improved adaptive threshold method is used to suppress random noise and improve the signal-to-noise ratio of micro seismic data.Combined with the fracturing operation curve and production performance curve,the geometric characteristics and spatial distribution of fracturing fractures are analyzed,and the fracturing reservoir reconstruction effect is evaluated.The main achievements and understandings are as follows:（1）The overall extension direction of fracturing fractures in the study area is basically consistent with the direction of regional principal stress.The effect of fracturing reservoir reconstruction is comprehensively affected by the monitoring distance,fracture mechanism,fracturing scale,petrophysical parameters,etc.new fractures are mainly caused by the opening of natural fractures caused by hydraulic fracturing and the fracture of reservoir caused by fracturing.（2）After CO₂ pre charging and fracturing,the elastic modulus and compressive strength of the rock stratum are reduced,and the Poisson’s ratio is increased,which is conducive to expanding the fracture network and improving the effect of repeated reconstruction.（3）The effective signal energy in the original microseismic data is weak,and the random noise greatly affects the quality of the microseismic data.In view of this,the improved adaptive threshold method is used to remove the random noise to the greatest extent.According to the difference of noise formation mechanism and propagation path,the suppression is carried out from the source to improve the quality of microseismic data.（4）The distance between the fracturing point and the geophone is positively correlated with the number of microseismic events.The closer the monitoring distance is,the more microseismic events are monitored by the geophone;There is no obvious linear relationship between the reservoir reconstruction volume SRV and the geophone monitoring distance.