摘要
水力压裂引起的地下岩石破裂通常发生在以压裂井为中心约200 m的水平范围内,利用地震干涉法恢复微地震地面监测资料的反射波,会导致虚源一侧恢复的反射波位于互相关正延迟中,而虚源另一侧恢复的反射波位于互相关负延迟中。如果仅根据互相关正延迟函数生成虚源地震道,则会导致互相延迟中的反射波信息丢失。为此,提出了将互相关正、负延迟函数相加的求和方法以及虚源及其接收点位置与压裂井位置关系的相对位置方法,这两种方法均可将丢失的反射波重新利用,且覆盖次数翻番,进而显著提高偏移成像质量。将上述方法分别应用于数值模型和四川某工区采集的微地震地面监测资料,应用结果表明:虚源道集的叠加剖面质量显著改善,与同位置的三维地震资料时间偏移剖面相吻合,且浅层反射波成像同相轴连续性好,证明了上述方法的有效性。
The rupture of underground rock caused by hydraulic fracturing usually occurs within a horizontal range of approximately 200 meters around the fracturing well.When seismic interferometry is used to recover reflected waves recorded by microseismic sensors,the reflected wave recovered on the virtual source side will have a cross-correlation function with a positive time lag,while the one recovered on the opposite side will have a negative time lag.Upon generating the seismic trace of the virtual source,if the cross-correlation function with positive time lag is taken,the information about the reflected wave with negative time lag will be lost.To address this limitation,this paper proposes a“summation method”for combining the cross-correlation functions with positive and negative time lags,and a“relative position method”for relating the position of the virtual source to those of the receiving point and the fracturing well.Using the proposed method,the information carried by the initially discarded reflected wave can be exploited,thus doubling the number of folds and improving the quality of the migration imaging remarkably.A numerical model together with microseismic surface monitoring data collected in Sichuan,China,were used to test the method.The results showed that the quality of the migration imaging of the virtual source was significantly improved,and was consistent with the time-migration profile of 3D surface seismic data at the same location.Moreover,the imaging events related to shallow reflected waves were more continuous,thereby confirming the effectiveness of the proposed method.
作者
陈国金
张亚红
宋吉杰
曹辉
吴永栓
CHEN Guojin;ZHANG Yahong;SONG Jijie;CAO Hui;WU Yongshuan(Sinopec Geophysical Research Institute,Nanjing 211103,China;Oil field Exploration&Development Department Sinopec,Beijing 100728,China)
出处
《石油物探》
EI
CSCD
北大核心
2020年第1期60-70,79,共12页
Geophysical Prospecting For Petroleum
基金
中国石化科技部项目(P13030)资助。
关键词
地震干涉法
微地震地面监测
反射波恢复
虚源地震道
求和方法
相对位置方法
seismic interferometry
micro-seismic surface monitoring
reflection retrieval
virtual seismic trace
summation method
relative position method
