彭水地区残留向斜常压页岩气地震采集实践  

Seismic data acquisition of normally pressured shale gas reservoirs in residual synclines in the Pengshui area,Sichuan Basin,China

作　　者：薛野[1] 杨帆[1] 赵苏城 蓝加达 XUE Ye;YANG Fan;ZHAO Su-Cheng;LAN Jia-Da(Research Institute of Exploration&Development,East Company,SINOPEC,Nanjing210007,China)

机构地区：[1]中国石化华东油气分公司勘探开发研究院,江苏南京210007

出　　处：《物探与化探》2023年第6期1490-1499,共10页Geophysical and Geochemical Exploration

基　　金：国家科技重大专项“彭水地区常压页岩气勘探开发示范工程”(2016ZX05061);中国石化科技开发部项目“常压页岩气地球物理评价技术研究”(P21087-3)。

摘　　要：中国南方常压页岩气主要分布于四川盆地外围的志留系残留向斜,资源潜力大。区内地质条件复杂,必须利用高信噪比地震资料精细刻画地下的构造特征并准确描述优质页岩的分布规律,提高水平井优质页岩钻遇率与钻井效率。自2011年起,在彭水地区持续开展了地震采集探索与实践。通过系统梳理总结已实施项目的方法、效果及不足,区域噪声特征分析,道距对静校正影响研究,三维地震观测系统退化分析,认为:①二维地震采集剖面五峰—龙马溪组页岩反射波组较清晰,支撑了常压页岩气的选区评价工作;②提出宽方位、低炮点密度、高横向覆盖次数以及中近偏移距信息丰富的三维观测系统设计原则;③三维地震处理剖面信噪比高、波组特征清楚,经实钻验证三维构造成像准确、地层深度预测误差<1%,有力支撑勘探开发。该技术体系可在类似常压页岩气探区推广。Normally pressured shale gas reservoirs in southern China,exhibiting significant potential resources,are primarily distributed in Silurian residual synclines at the periphery of the Sichuan Basin.Given intricate geological conditions in the study area,seismic data with high signal-to-noise ratios(SNRs)are required for fine-scale characterization of underground structural features and accurate de-scription of the distribution patterns of high-quality shales.The purpose is to improve the probability of penetration of high-quality shales in horizontal wells and the drilling efficiency.Since 2011,the research and application of seismic data acquisition have been continually conducted in the Pengshui area.This study systematically summarized the methods,effects,and deficiencies of relevant projects imple-mented,and analyzed regional noise characteristics,the influence of channel spacing on static correction,and the degradation of the 3D seismic observation system.The results are shown as follows:(1)The 2D seismic data acquisition profiles displayed relatively clear re-flection wave groups of shales in the Wufeng-Longmaxi formations,supporting the target selection and evaluation of normally pressured shale gas reservoirs;(2)The design principles of a 3D observation system,characterized by a wide azimuth,a low shot density,a high lateral fold number,and rich medium-near offset information,were proposed in this study;(3)The 3D seismic data processing profiles manifested high SNRs and clear wave group characteristics.The drilling results reveal accurate 3D structure imaging and a formation depth prediction error below 1%,strongly supporting shale gas exploration and production.The technical system in this study can be ap-plied to similar exploration areas of normally pressured shale gas reservoirs.

关 键 词：残留向斜 常压页岩气 地震采集 观测系统 信噪比 

分 类 号：P631.4[天文地球—地质矿产勘探]