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对非常规油气藏,断层既可以成为油气的流通通道,也可能成为油气藏开采开发的阻碍,体现在(1)导致压裂液的滤失;(2)导致储层水淹;(3)诱发小型地震。因地震勘探分辨率的影响使得部分小型断层无法被有效检测,该类断层在压裂施工过程中变得异常活跃并释放出大量的微震。为此,本文总结出一种融合微震时空特征、相对震级、震源机制、振幅、频率的天然断层识别方法。该方法基于储层力学机理分析天然断层和压裂裂缝激发的力学环境,并得出其时空分布规律;通过引入微地震相对震级的算法对天然断层和压裂裂缝活动所致的微地震事件进行标定,并基于地震位移理论分析天然断层和压裂裂缝所致微震的动力学特征,得出其在频率和振幅存在的差异。通过微地震地面和井中监测实例的应用和验证,该方法能有效地达到对天然断层和压裂裂缝识别的目的。
For unconventional oil and gas reservoirs, the fault can act as both a flow channel for oil and gas and an obstacle to the exploration and development of oil and gas reservoirs, as shown in (1) leading to fluid loss in the fracturing fluid, (2) water flooding in the reservoir, (3) Induced small earthquakes. Due to the resolution of seismic exploration, some small faults can not be effectively detected. Such faults become extremely active during fracturing and release a large number of microseisms. For this reason, this paper summarizes a natural fault recognition method that integrates the features of microseismic space-time, relative magnitude, source mechanism, amplitude and frequency. Based on the mechanism of reservoir mechanics, this method analyzes the mechanical environment stimulated by natural faults and fractures, and obtains the spatial and temporal distribution rules. The microseismic events caused by natural faults and fractures are introduced by introducing the relative magnitude of microseismicity Based on the theory of seismic displacement, the dynamic characteristics of microseismicity caused by natural faults and fractures were analyzed. The differences in frequency and amplitude were obtained. Through the application and verification of micro-seismic ground and well monitoring examples, this method can effectively achieve the purpose of identifying natural faults and fractures.