【摘要】 微地震监测定位中,速度模型的准确性对定位精度起着至关重要的作用.在非常规油气藏压裂的微地震监测中,往往根据分段射孔或导爆索触发地震波达到对地下速度模型反演及相关参数校正的目的.然而受射孔的数量及记录信噪比的影响,使得基于射孔资料反演的速度模型不能完全表征整个区域的准确速度值,从而最终影响速度反演及定位的精度.压裂涉及区域微地震震源位置是未知的,这无疑让定位精度的验证变得极其困难.文章基于速度模型与传播路径的旅行时关系公式推导得出速度模型反演存在误差的原因,并得出定位精度与微地震事件和检波器之间距离的关系.结合理论数值模拟的定量分析表明,经过射孔资料校正的速度能够较高精度地对射孔附近的微地震事件定位,而对偏离射孔位置较远的微地震事件将出现较大的定位误差,通过实际射孔资料的重定位及分段压裂微地震事件定位结果有效地验证了该论点,从而为基于微地震信息的压裂裂缝体的评判提供必要的指导.更多还原

【Abstract】 The accuracy of the velocity model has an important role in microseismic monitoring location.It is always inverting the velocity model and some other characters by seismic wave which triggered by multi-stage perforations and shots.However,the velocity model can’t represent the overall underground velocity because of the limited perforation number and the S/N ratio of the recording,and eventually affects the location precision.It is also difficult to testify the location precision because the microseismic location which the fracturing concerned is unknown.Based on the specific velocity model and travel time relation formula,the paper concludes the factor which caused the inverted velocity error,and gets the idea that the location precision is concerned with the propagation path of the perforation and microseismic.Combined with the numerical analysis and the actual data microseismic event location,it has the relationship that the nearer distance between the perforation and microseismic location,the higher location precision.Eventually,it will direct the fracturing fracture interpretation based on the microseismic location distribution.更多还原