Research On The Source Location Accuracy And Optimal Geophone Array Designs For The Oil Well Microseismic Fracture Monitoring

Because of the shortage of the energy in the world, the exploitation of the high-permeability oil and gas fields has now entered into a final stage.. In order to increase oil production, people has again turned their attention to the exploitation of resources in the low-permeability oil and gas fields. The majority of the economic exploitation of oil and gas in the low-permeability reservoir requires the use of hydraulic fracturing. However, whether the hydraulic fracturing can achieve good results in the oil and gas production or not, requires an effective monitoring method to make reasonable interpretation and evaluation. Is it understood that the microseismic monitoring technology has undergone rapid development recently. It has been widely used in various fields such as hydraulic fracturing cracks microseismic monitoring, dynamic monitoring of oil and gas wells, etc, and has been highly recognized by the petroleum industry. This paper has therefore selected microseismic monitoring technique as fracture monitoring method.In the oil well fracture microseismic monitoring, the study of the accuracy of the microseismic source location and the optimal design of the geophone network is helpful to interpret the hydraulic fracture orientation, shape and accurately evaluate the fracturing effect. It will play a guidance role on the fracturing design optimization, reasonable distribution of the overall development and the correct layout of the network of injection wells, and to improve oil and gas resources exploitation rate. However, there are relatively few publications in this field. Domestic implementations of the technology utilize only a few geophones in data collection. The reliability and accuracy of microseismic source location are low. Therefore, this paper carries out a detailed study on the microseismic source location accuracy and optimal designed of the geophone network.Regarding to the monitoring system used in microseismic monitoring technique, through the investigation of the development of microseismic monitoring technology in the world, we noticed that, there are more theoretical studies on the technology, but there are less equipment research and development. Therefore, this paper carries out a detailed study on the oil well microseismic fracture monitoring system, presents an overall design of the microseismic monitoring system, and introduces the theoretical foundation of the monitoring system in detail. Meanwhile, the paper integrates the advantages of both surface and borehole monitoring, proposes a combined surface and borehole monitoring method with good signal credibility, interference elimination and operability.Microseismic monitoring technology is to monitor microseismic events in the fracturing process. Microseismic events produce seismic waves, which can be detected by a network of geophones. This constitutes the theoretical basis of the source location, and establishes the principle model of the source location in the oil well microseismic fracture monitoring.The microseismic signals acquired by the geophones contain various kinds of noise. This paper carries out pre-processing such as filtering and signal extraction, etc, on microseismic data. For the study of source location accuracy, we first establish the nonlinear regression model as the source location algorithm, and then analyze microseismic positioning inversion algorithm of solving nonlinear regression models.The Gauss-Newton algorithm is used to solve the souce location equation., Its convergence is adjusted. Then a simulated experiment of the source location algorithm is performced. The experiment shows that the algorithm is relatively accurate that the micro-source point position anti-performance by this correction Gauss-Newton iteration inversion method. Last, discussed source location accuracy problem, considering the impact of factors of the micro-source location accuracy, analyzed sources of positioning errors in the micro-seismic monitoring positioning, to estimate the location error, and thus gained the positioning accuracy of the algorithm.Taking into account the operation the micro-seismic positioning data interpretation, developed and designed the operating software with friendly user interface using MATLAB, first from the angle of the conventional software development process, analyzed in detail need to achieve functions in the data interpretation software aspect required by micro-seismic monitoring system, according to the overall architecture design of software, implemented Each module by programming, developed the software has user-friendly operation.Optimization design of micro-seismic monitoring detector observatory network is the conditions forming a good solution of positioning equations, thus it reduced the range of the micro-source location error, how to lineup detectors, which directly impact on the source location accuracy, therefore, in order to reduce effect the detector lineup to positioning accuracy, get a better monitoring, carried out a detailed study to optimization design of the micro-seismic monitoring detector observatory network. By combination of diversified the station location, get a variety of station lineup plans, then calculate positioning error, and draw standard error map of three-dimensional coordinates of the spatial position of the micro-source network point, take a detailed comparison and explain of the positioning accuracy of the various plans, and Take cross detector lineup plan for instance, study the matter of the use efficiency of the detector; Finally, boiled down to some optimization and design principles of detector observatory network in micro-seismic monitoring.Finally, using simulated micro-seismic test methods, validate the accuracy of the positioning error analysis and the feasibility of optimization design of, give the experimental methods and results, and analyze the problems in the experiment.