基于分布式光纤同井微振动监测数据的页岩气水平井压裂微地震震源位置成像  

Microseismic source location imaging using in-well distributed fiber-optic monitoring data during horizontal well fracturing in shale gas reservoir

作　　者：梁兴[1] 王一博[2] 武绍江 梁恩茂 史树有 张朝[1] LIANG Xing;WANG YiBo;WU ShaoJiang;LIANG EnMao;SHI ShuYou;ZHANG Zhao(PetroChina Zhejiang Oilfield Company,Hangzhou 311100,China;Institute of Geology and Geophysics,Chinese Academy of Sciences,Beijing 100029,China;China Shipbuilding Industry Company Limited 715 Research Institute,Hangzhou 310023,China)

机构地区：[1]中国石油天然气股份有限公司浙江油田分公司,杭州311100 [2]中国科学院地质与地球物理研究所,北京100029 [3]中国船舶集团第715研究所,杭州310023

出　　处：《地球物理学报》2022年第12期4846-4857,共12页Chinese Journal of Geophysics

基　　金：中国石油天然气集团公司重大工程技术现场试验专项(2019F-31和2020F-44);国家重点研发计划(2021YFA0716800);中国科学院稳定支持基础研究领域青年团队计划(YSBR-020)资助.

摘　　要：水力压裂是进行非常规油气资源开发的核心技术.微地震监测技术可以对水力压裂储层改造过程进行监测和评估,为安全高效压裂施工提供技术保障.近年来,分布式光纤声波传感(Fiber-optic Distributed Acoustic Sensing,DAS)技术开始应用于水力压裂人造裂缝监测,并展示出巨大的潜力.我们将光纤永置式布设于页岩气储层水平井套管外,同时在该监测井实施水力压裂,实现了基于水平井DAS的水力压裂过程同井微振动实时监测.同井监测时,监测井与压裂改造区距离较近,垂直于监测井方向的采集方位角较窄,导致基于扫描叠加原理的常规震源位置成像结果分辨率较差;此外,原始数据波形通常存在极性反转现象,对波形叠加成像的准确性有一定影响.本文提出了基于波形包络和混合成像条件的震源位置成像方法,可以有效提高微地震震源位置成像的精度.合成数据算例表明本文提出的新方法具有以下两点优势:①使用波形包络可以避免原始数据波形极性反转对成像准确性的影响;②使用混合成像条件可以压制成像假象,并提升震源位置成像分辨率.本文对昭通页岩气储层水力压裂人造裂缝监测的实际数据进行了分析,结果表明本文提出的新方法能够提高同井DAS监测微地震震源位置成像的空间分辨率和准确性.Hydraulic fracturing is an indispensable technology for the development of unconventional oil and gas resource reservoirs.To improve the efficiency of fracturing,microseismic monitoring is widely used to monitor and evaluate the reservoir stimulation.Recently,fiber-optic distributed acoustic sensing(DAS)technology has been applied to microseismic monitoring in hydraulic fracturing and shown great potential.By installing the fiber permanently outside the casing of the horizontal well and playing fracturing in the monitoring well,we perform a real-time DAS monitoring of in-well hydraulic fracturing of horizontal well.In the in-well monitoring,the monitoring well is close to the fracturing zone,and its acquisition azimuth perpendicular to the monitoring well is relatively narrow,resulting in poor resolution of the conventional source location stacking algorithm;furthermore,the strong polarity reversal of the waveforms,which will affect the accuracy of stacking image.In this study,we propose a hybrid imaging condition based stacking algorithm using waveform envelopes.The synthetic examples show that the proposed method has the following two advantages:①using the waveform envelope can reduce the polarity reversal and improve the accuracy of stacking image;②using hybrid imaging condition can suppress stacking artifact and improve the resolution of the source location image.We further analyze real data from Zhaotong shale gas project,and the results show that the proposed method can improve the spatial resolution and accuracy of the source location image.

关 键 词：页岩气储层 水力压裂 分布式光纤声波传感 同井监测 微振动 震源位置成像 

分 类 号：P631[天文地球—地质矿产勘探]