Study On Crosshole Microseismic Source Location Method For Hydraulic Fracturing

Microseismic monitoring is a most accurately, timely, and information abundantlytechnology for monitoring reservoir fracturing in the process of oil and gas reservoirexploration and development. Based on signal analysis of microseismic data and eventrecognition, locating the the epicenter of the micro-seismic events, high reliability extractingattribute parameters of oil and gas reservoir, get urgent needed geophysical data forevaluating reservoir productivity and guiding the oil (gas) reservoir exploration andexploitation, this is the basic framework of microseismic data processing. Based on this, thethesis will study on the micro-earthquake hypocenter and the practical software developmentof which as follows.Based on the demands of micro-earthquake hypocenter technology road and earthquakedata, aimed at three common collection methods of earthquake data(the single shaft, the singleinclined and mixed well three cases), the thesis implemented and completed ray tracingalgorithm design of micro-seismic signals forward modeling in a uniform medium andlayered medium model, this forward algorithm can imitate the complex distribution ofmicro-earthquake event at certain time and space,and with the function of three-dimensionallayered media ray tracing at planar interface.In order to make the wide range ray tracing ahigher success rate, multi-step high-precision ray tracing processing idea is adopted in thisthesis,achieved the synthesis of multi-event three-component micro-earthquake data.The thesis implements two micro-earthquake hypocenters(inversion) method. The firstmethod is the travel time inversion of same type wave, this method is based on themicro-seismic events have been effectively identified, establish the initial velocity modelrelying on logging data or perforating record, using LM (Levenberg-Marquardt) algorithm,for each identified micro-seismic events (phase axis),use grid search method for velocityinversion in the monitoring area.In Simple micro-seismic data acquisition model, in order tosolve the problem of the inversion results Multiplicity of Solutions, vector end of the curveand covariance matrix method are used to calculate polarization angle, polarization angle is used for secondary positioning for initial inversion results. The secondary inversion method isfocal scanning algorithms based on the waveform(Source-Scanning Algorithm--SSA), intheory, the algorithm need not incident pickup, however, in order to improve the efficiency ofscanning as possible, before scanning the focal energy ratio method is used to pick up for thefragments that on the presence of micro-seismic events of all the records. The processing ofvelocity models is same with the firstly method; in order to reduce the multiple solutions ofthe inversion results and improve the noise immunity of the procedure, usingthree-component recording synthetic track component and calculate the envelope of thetracking component with Hilbert change, which as the basis of focal scan. In order to makethe results of the scan higher accuracy, but also to minimize the scan job, first during thescanning process the grid scan a wide range to determine the scope of the event, and then thesmall grid scan the determined the range, to determine the specific attribute parameter offractures. Finally, multi-model data test to verify the reliability of both inversion methods.