The application of prestack geostatistical inversion in the prediction of shale sweet spots and thin interbeds: a case study of Block W in Western Canada Basin
GUO Tongcui1, JIANG Mingjun2, JI Yingzhang2, WANG Hongjun1, MA Wenji3, KONG Xiangwen1
1. Research Institute of Petroleum Exploration and Development, PetroChina, Beijing 100083, China; 2. CNODC, CNPC, Beijing 100034, China; 3. School of Electronics Engineering and Computer Science, Peking University, Beijing 100054, China
Abstract：Shale gas is a kind of unconventional natural gas.The prediction of shale "sweet spots" with high TOC,high brittleness and developed fractures between wells is always an important step in shale gas exploration and development in the regions with few wells.The target shale formation in Block W in Western Canada Basin is relatively thin (the maximal seismic reflection time is 20ms),and contains multiple thin limestone interlayers (0.5~3m).There are overlapping intervals between the P-wave impedances of brittle shales and duct ile mudstones.It is difficult to predict shale sweet spots and thin limestone interbeds using seismic data.In this paper,a rock physics template for evaluating shale "sweet spots" was established based on the analysis on the rock-physical elastic parameters,and the elastic characteristics of shale "sweet spots" and interbeds were clarified.The 3D lithology-constrained pre-stack geostatistical inversion technique was used to predict the shale with high TOC and high brittleness,as well as limestone interbeds.Firstly,the rock physics parameters of the shale reservoir were analyzed.The prospective shale objectives have low Poisson's ratio,median Young's modulus,high TOC and high brittleness,while the limestone interbeds have high Poisson's ratio,high Young's modulus,low TOC and high density.Secondly,1D constrained geostatistical inversion was applied to predict and test the parameters of prospective shale area and interbeds.Thirdly,3D constrained prestack geostatistical inversion was applied to predict prospective shale area and interbeds.The results showed that the overlapping areas of high-TOC and high-brittleness shale and developed fractures are the target shale "sweet spots".The developed shale "sweet spots" area with thin limestone interbeds are chosen as the prospecting well location area,in order to ensure a high probability that horizontal well drills to high-quality reservoirs with high gas production..
郭同翠, 姜明军, 纪迎章, 王红军, 马文骥, 孔祥文. 叠前地质统计学反演在页岩甜点和薄夹层预测中的应用——以西加拿大盆地W区块为例[J]. 石油地球物理勘探, 2020, 55(1): 167-175.
GUO Tongcui, JIANG Mingjun, JI Yingzhang, WANG Hongjun, MA Wenji, KONG Xiangwen. The application of prestack geostatistical inversion in the prediction of shale sweet spots and thin interbeds: a case study of Block W in Western Canada Basin. Oil Geophysical Prospecting, 2020, 55(1): 167-175.
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