Borehole Microseismic Forward Modeling And Inversion Location Of The Non-horizontal Layered Model

Borehole microseismic detection technology can realize the monitoring of reservoir fracturing fractures, and drive real-time monitoring of oil reservoir after water injection or gas injection. It has the vital significance in the oil field exploration and development. One of key parts of this technology is positioning the event accurately, papers study from the forward modeling theory, algorithm, microseismic events and seismic inversion positioning, and has realized the accurate localization of borehole microseismic source.According to the characteristics of the borehole microseismic, it has discussed the iterative forward modeling problem of ray tracing. And according to the characteristics of this method, forward problem of iterative method of ray tracing is discussed and according to the characteristics of this method, walking forward of inclined interface and bending interface layered model is studied deeply, and according to the wave propagation characteristics, wave amplitude of the forward problem under different interface are discussed. According to calculating of the traveltime and amplitude of the synthetic seismic records, it also lays a good foundation for the microseismic inversion at the same time.Paper analyzes the actual information characteristics of borehole microseismic, illustrates the grid search method and advantages and disadvantages of simulated atomic transition methods, as well as the adaptability and accuracy in the actual wells microseismic data processing problem, grid search method and simulated atomic transition method of hybrid inversion method is proposed, it learned the advantages of two methods:the convergence speed of the grid search method and high precision of the simulated atomic transition method. It makes up the deficiency of the two methods:the precision of the grid search method and simulated atomic transition method needs a large number of initial model and time consuming. Hybrid inversion method has the characteristics of fast convergence speed, high precision, and can avoid falling into local minimum value, good stability, strong adaptability and so on, but in the practical application for seismic data processing it don’t achieve good results. In borehole micro positioning of micro seismic events of the actual seismic data, it needs to use the logging curve analysis to establish initial velocity model and establish proper observation system and the known of microseismic events and the corresponding perforating data correction to calibrate the initial model.Using the hybrid inversion algorithm proposed and studied in this paper to solve practical micro seismic source localization, and using the big long grid search method to qualitative the true solution of the model space, this greatly reduce the work of selecting the quantity of initial model parameters in simulated atomic transition inversion algorithm, and improve the efficiency of computing. After selected the corresponding model space, using the steepest descent method get the distribution of local minimum value, simulated atomic transition process to calculate the global minimum of object function and its corresponding model parameters. Using grid search and simulated atomic transition hybrid inversion algorithm to locate the actual borehole microseismic events at the beginning orientation and focal position, this reduced the positioning error. Compared with the result of the superposition of scanning, it has verified the feasibility of complete wells micro-seismic inversion methods.