多波地震联合技术精细雕刻隐蔽河道砂体——以四川盆地西北部ZT地区沙溪庙组为例  

Multi-wave seismic based depiction of subtle channel sandbody:A case study of the Shaximiao Formation in the ZT area,northwestern Sichuan Basin

作　　者：冉崎[1] 魏玮 陈康[1] 杨广广 戴隽成 闫媛媛 吕龑 马华灵[2] 朱讯 RAN Qi;WEI Wei;CHEN Kang;YANG Guangguang;DAI Juancheng;YAN Yuanyuan;LYU Yan;MA Hualing;ZHU Xun(Exploration and Development Research Institute,PetroChina Southwest Oil&Gasfield Company,Chengdu,Sichuan 610095,China;PetroChina Southwest Oil&Gasfield Company,Chengdu,Sichuan 610056,China;Field Development Management Department,PetroChina Southwest Oil&Gasfield Company,Chengdu,Sichuan 610056,China)

机构地区：[1]中国石油西南油气田公司勘探开发研究院 [2]中国石油西南油气田公司 [3]中国石油西南油气田公司气田开发管理部

出　　处：《天然气工业》2024年第3期87-96,共10页Natural Gas Industry

基　　金：中国石油西南油气田公司科学研究与技术开发项目“四川盆地中西部地区致密气成藏条件及物探关键技术研究”(编号:2022ZD01-01)。

摘　　要：四川盆地陆相致密砂岩气资源丰富,是目前天然气增储上产的重要领域,但侏罗系沙溪庙组沙一段河道砂体纵向多期叠置,横向同期交汇且河道砂体类型多样,隐蔽性强,形成了复杂多变的地震反射特征,准确刻画河道砂体难度极大。为了解决四川盆地西北部(以下简称川西北)ZT地区沙溪庙组一段(以下简称沙一段)多期河道砂体及储层刻画不清晰、精度低的问题,采用新采集的三维地震三分量转换横波(PS波)资料,结合PP波叠前数据和常规叠后地震资料,在正演模拟基础上,形成了多波地震联合雕刻河道砂体关键技术,并分析了河道砂体多波地震响应特征随砂体孔隙度的变化规律。研究结果表明:(1)砂体顶界PP波地震响应随孔隙度增大由强波峰转变为强波谷,而PS波地震响应不随物性变化发生极性反转,基于横波对岩性的刻画可有效识别多期隐蔽河道砂体;(2)相较反映横波阻抗变化率的叠前P-G属性,PS波振幅能量更聚焦,雕刻的河道砂体横向展布特征更清晰,边界更清楚;(3)叠前P-G属性具有更高的纵向分辨率,有利于区分叠置砂体,并落实砂体的发育期次。结论认为,多波地震技术联合充分发挥P-G的高分辨率优势确定纵向砂体发育期次,发挥PS波横向连续性优势刻画横向边界,实现了ZT地区沙一段河道砂体的完整精细雕刻,生产应用效果显著,并为该区井位部署和储量升级提供了有力技术支撑,为四川盆地陆相致密砂岩气规模效益开发奠定了坚实的基础,同时有力推进了多波地震勘探技术的发展。Tontinental tight sandstone gas is abundant in the Sichuan Basin,and it is an important option for incremental gas reserves/production.The channel sandbodies in the first member of the Jurassic Shaximiao Formation(Sha 1 Member) in the basin are vertically superimposed in multiple periods and laterally crisscrossed in the same period.Moreover,the channel sandbodies are diverse and subtle.They reflect complex and variable seismic responses,making their depiction very challenging.In the ZT area,northwestern Sichuan Basin,the multi-period channel sandbodies and reservoirs of Sha 1 Member are described unclearly with a low accuracy.To address this problem,using the newly collected three-dimensional three-component converted transverse wave(PS wave) seismic data,combined with the pre-stack and post-stack PP-wave seismic data,this paper develops a key technique of multi-wave seismic based depiction of channel sandbodies on the basis of forward simulation.With the support of this technique,the multi-wave seismic responses of channel sandbodies with the variation of sandbody porosity are analyzed.The results show that the PP-wave seismic responses at the sandbody top change from strong wave crest to strong wave trough with the increase of porosity,while the polarity of PS wave seismic responses does not reverse with the change of physical properties.The lithological characterization based on PS wave can effectively identity multiperiod subtle channel sandbodies.Compared with the pre-stack P-G attribute that reflects the rate of change of PS wave impedance,the amplitude energy of PS wave is more focused,and the sandbodies depicted by PS wave have clearer lateral distribution with more visible boundaries.The pre-stack P-G attribute has a higher vertical resolution,which is conducive to distinguishing the stacked sandbodies and determining their periods.The proposed multi-wave seismic based technique makes full use of the high resolution of pre-stack P-G attribute to define the vertical periods of sandbodies and the lateral

关 键 词：四川盆地 侏罗系沙溪庙组 致密砂岩 转换横波 多波地震勘探 河道砂体刻画 叠前P-G属性 

分 类 号：P631.44[天文地球—地质矿产勘探]