Method Research Of Micro-seismic Source Location In Hydraulic Fracturing Monitoring

Hydraulic fracturing technique is not only a powerful assistant for the promotion of conventional reservoirs production,but also a key technology for the development of unconventional resources.Therefore,the micro-seismic monitoring is of great significance.Based on the three-dimensional(3D)micro-seismic monitoring,the information of the generated fracture during the process of hydraulic fracturing can be got,including the length,width,height and the orientation of induced fractures,which can be used to evaluate the effect of fracturing further.In fact,the key part of microseismic fracturing monitoring is the event location,obtaining the spatial distribution of the source to obtain the fracture information.Thus,the methods and studies in this paper are significant.The main content of this paper has two parts: ray tracing and event location.Ray tracing is the prerequisite and basis for event location.In the part of ray tracing,the main work implemented is the fast marching method(FMM),which is a new grid-based numerical algorithm.This paper briefly discusses the implementation process and basic principles of FMM,and some improvements have been made based on this method.Then the new method is applied to a variety of geological model for verification and obtaining the simulation field of the travel time based on the improved FMM algorithm.Finally the forward modeling of ray tracing from 2D to 3D models is completed,the results show that the improved FMM method is fast,stable and reliable,which can prepare for the follow-up work and lay the foundation for source location inversion.In the part of event location,multiple methods are studied and compared,and finally the paper focuses on the analysis of the intersection method and the grid searching method.Then the location technique is completed which combines the intersection method and the grid search method based on the fast marching method.The results show that both the intersection method and the grid search method can quickly and accurately obtain the information of event location.The algorithms are stable and have good convergence,which means they are good methods for event location.