基于声学特性的致密砂岩储层含气性评价  

Gas-bearing evaluation of tight sandstone reservoir based on acoustic characteristics

作　　者：周彦球 王贵文[1,2] 江程舟 刘秉昌 解宇强 赖强[3] 夏小勇 ZHOU Yanqiu;WANG Guiwen;JIANG Chengzhou;LIU Bingchang;XIE Yuqiang;LAI Qiang;XIA Xiaoyong(College of Geosciences,China University of Petroleum(Beijing),Beijing 102249,China;State Key Laboratory of Petroleum Resources and Prospecting,China University of Petroleum(Beijing),Beijing 102249,China;Research Institute of Exploration and Development,PetroChina Southwest Oil and Gasfield Company,Chengdu 610041,China)

机构地区：[1]中国石油大学(北京)地球科学学院,北京102249 [2]中国石油大学(北京)油气资源与探测国家重点实验室,北京102249 [3]中国石油西南油气田分公司勘探开发研究院,四川成都610041

出　　处：《天然气地球科学》2022年第5期831-841,共11页Natural Gas Geoscience

基　　金：国家自然科学基金项目“致密混积岩储层孔喉网络体系成因机理与多尺度表征评价研究”(编号:41872133);中国石油天然气集团公司与中国石油大学(北京)战略协作项目“四川盆地陆相致密气、页岩油气成藏规律研究”联合资助.

摘　　要：以四川盆地金华—中台山地区沙溪庙组为例,研究致密砂岩储层的声学特性在含气性识别、饱和度计算及产能预测中的应用。通过30块岩样的变饱和度声波实验,分析纵横波时差、纵横波速度比随孔隙度、含水饱和度的变化规律,形成局部增强的声速图版及线性判别边界,进而建立分段饱和度模型。经试气资料验证,改进的声速图版可有效地识别Ⅰ、Ⅱ类气层,符合率为87.5%;基于声波实验的饱和度模型仅需少量测井曲线作为输入项,简单实用,计算的含水饱和度与岩心分析一致性好。在此基础上,通过数值积分求取储层的累积含气厚度,结合试气资料分别建立直井段与水平井段的产能预测模型,其决定系数R;分别为0.83和0.67,可有效指导研究区产能预测。还分析比较了基于Gassmann方程的声学饱和度模型,认为该类模型所需理论参数较多,不确定性较大,而且存在伪边界效应,实验数据和测井资料均证实其适用性较差。Taking Shaximiao Formation in Jinhua-Zhongtaishan area of Sichuan Basin as a case,this paper makes a study on the application of acoustic characteristics of tight sandstone reservoirs in gas-bearing identification,saturation calculation and productivity prediction. Through an acoustic experiment of variable saturations of 30 rock samples,the variation laws of P-and S-wave slowness and the velocity ratio with porosity and water saturation are analyzed,and a locally enhanced acoustic velocity chart and its linear discriminant boundary are formed,and then a piecewise saturation model is established. Verified by the gas test data,the improved velocity chart can effectively identify type Ⅰ and Ⅱ gas reservoirs,with a coincidence rate of 87.5%;the saturation model based on the experiment requires only a few logs as input items,which is simple and easy,and the calculated water saturation is in good agreement with core analysis. On this basis,the“cumulative gas bearing thickness”of the reservoir is calculated by numerical integration,and combined with the gas test data,the productivity prediction models of vertical and horizontal well section are established respectively,with determination coefficients of 0.83 and 0.67,respectively,which can effectively guide the productivity prediction in the study area.The acoustic saturation model based on Gassmann equation is also analyzed and compared. This kind of model is found to require more theoretical parameters and has a greater uncertainty and pseudo boundary effect. Its poor applicability is proved by both the experiment and logging data.

关 键 词：声波实验 纵横波速度比 饱和度 Lowess曲面 GASSMANN方程 累积含气厚度 

分 类 号：TE132.1[石油与天然气工程—油气勘探]