NC区块页岩气水平井压裂微震实时监测  

Real-time microseismic monitoring for the hydraulic fracture of horizontal wells at NC block

作　　者：房大志[1] 谷红陶 钱劲 甘宇 梁北援 FANG DaZhi;GU HongTao;QIAN Jin;GAN Yu;LIANG BeiYuan(Sinopec Shale Gas of Chongqing,Chongqing 408400,China;Dayu Petroleum Technology,Qianjiang 433124,China;GeoImage LLC,CO 80016,USA)

机构地区：[1]中国石化重庆页岩气有限公司,重庆408400 [2]江汉油田大宇石油技术开发潜江有限公司,潜江433124 [3]GeoImage LLC,CO 80016,USA

出　　处：《地球物理学进展》2022年第2期577-587,共11页Progress in Geophysics

基　　金：国家科技重大专项(2016ZX05061-003)资助.

摘　　要：页岩气储层压裂时微震微小、对其地面监测的记录数据信噪比(S/N)很低,常常<10%.且这些微震多为剪破裂,在不同地点的记录波动具有很强的正负极性.因此,在数据采集过程中需要躲避噪声源、进而有效去噪,以提高剪切破裂的S/N.为了提高微震监测成果在压裂过程中的实用性,需要对整个压裂过程采用实时监测的裂缝描述,为压裂泵注程序优化及时提供参考数据和指导.中国石化重庆页岩气有限公司在2020年5月应用微破裂向量扫描技术对NC区块的三口水平井的压裂进行了地面微震实时监测.三口井埋深3452~3667 m,共压裂和监测了56段.因满足了安静点观测及去噪的应用微破裂向量扫描的必要条件,输出结果可靠.实时观察了每段缝网的发展,有显著的间歇性和跳跃性.每段缝网均由多条交叉子破裂带组成,平均的主走向NE110°、全长470 m、宽度为长度的一半弱,井组地域平均最大主压应力方向应在NE110°~140°之间.由于实时监测,根据缝网当前形态,及时采取了变换排量和砂比等参数,辅以暂堵、改变液性、和停泵转向等手段,实现了更大的改造体积.The raptures of hydraulic-fracture in shale gas layers are tiny,and the signal over noise(S/N)recorded in seismic detection on surface is very small,e.g.in general S/N<10%.The microseismic is also,most of cases,shear event which releases shear waves with positive and negative polarities at different record regions.We have to,therefore,avoid noisy sources and denoise in data processing for the best S/N.The microseismic monitoring needs to be real-time,in addition,for optimizing the stimulation progress in time.Sinopec Shale Gas of Chongqing,China,implemented hydraulic-fracture for the 56 stages of 3 horizontal wells at NC block with a depth range of 3452~3667 m in 05/2020.The Vector Scanning(VS)was used to real-time monitoring the process by a microseismic network on surface.We followed strictly the necessary conditions required by VS application,so that the monitoring quality was satisfied.The development of the fracture net of each stage,with apparently intermittent in time and discontinues in space,was real-time observed in a range of about 5~10 min.The fracture net of each stage,in general,consists of many subfractures,with an average orientation NE110°,a length of 470 m,and a width close to the half of length;and the orientation of the maximum main stress should be in a range of NE110°~140°.The real-time monitoring helps to optimize effectively the injection process:based on the real-time observed geometric status of the nets,the adjusting parameters of stimulation,stopping pump,changing orientation,and temporary plugging were used promptly,such that the greater volume of reservoir stimulation was achieved.

关 键 词：水力压裂 微地震 页岩气 向量扫描 实时监测 

分 类 号：P631[天文地球—地质矿产勘探]