Research On Positioning Technology Of Fracturing Micro-seismic Source Place Of Oil Well Based On The Genetic Algorithm

In the age of oil reserves being shorted day by day, the need of oil source isincreasing rapidly. Exploitation of old oil region of the remaining oil, lowpermeability reservoir and density of viscous oil reservoir has become an integral partof today’s increase in oil production. Such regional oil storage that is different fromthe natural penetration high permeability oil field increased the difficulty of theimplementation of mining. The people have a different approach to solve this problem,which the micro-seismic monitoring of hydraulic fracturing technology proved to bevery efficient and the most commonly used means. In the actual Reservoirdevelopment process, the micro-seismic events is very weak, it is difficult todetermine the length and direction of the cracks, so accurate inversion of the micro-source location is the key factor to determine the fracturing effect. Looking for agood source location method has become the focus of all the attention, in this paper,mainly researched micro-seismic source inversion method for this case based on theforeign advanced technology.Firstly this article focuses on the discussion of the non-linear inversion methodof micro-seismic events, and gives the representative genetic algorithm methods,gradient descent method, grid method and simulated annealing method. At the sametime, analyzes the advantages and disadvantages of various methods in theimplementation process, combined with the practical needs of key points andconcludes the way that combined the relatively simple grid search method in theheuristic inversion with the relatively effective genetic algorithm in non-heuristicinversion can achieved the desired results as the inversion method of micro-seismicevents.According to the conventional inversion process, the article discusses the raytracing method and achieves it. And using shooting method to racing the ray path, in order to obtain the ray path and ray travel time. For underground medium conditionsand actual need respectively established the uneven medium speed model and thehorizontal layer uneven medium speed model, and ray tracing forward modelingprogram to calculate the ray path and travel time of the analog source in two differentmodels. Then the article summed up a set of methods for velocity model updatingCombined with the previous inversion experience, in order to more accuratesimulation stratum situation in the practical application. Due to the time when theseismic signal reach to be needed for the seismic signal theory travel time, so thepaper compared the method of commonly used relevant law and energy analogymethod, and chose the energy analogy method to extract the first signal, next make upthe method’s shortcoming.The Analytical method inversion of the homogeneous medium model is used tosimulate the homogeneous medium model and the horizontally layered homogeneousmedium model inversion. We compare to the results and analysis of existing problems,in order to lead to the necessity of using a nonlinear inversion method for the slightlymore complex model. Then have a detailed analysis and presentations for how toachieve the joint inversion method of grid search and genetic algorithms, andcombined with the characteristics of the extraction of micro-seismic events unable todetermine the micro-seismic origin time, then record seismic waves to the timedifference as the inversion of the theoretical parameters. We analog the source dataand validation the feasibility and rationality of the joint inversion method of gridsearch and genetic algorithms on the base of the above theory. At the same timeproved in this paper the method of using the analytic method compared to theconventional inversion and the single nonlinear inversion method both speed andaccuracy has greatly risen. Finally, according to the needs in the process of processingthe actual micro-seismic data, the article sums up a complete set of inversion process.