Electric property evidences of the carbonification of organic matters in marine shales and its geologic significance: A case of the Lower Cambrian Qiongzhusi Shale in southern Sichuan Basin

被引：27
作者：
Wang, Yuman [1 ]
Dong, Dazhong [1 ]
Cheng, Xiangzhi [1 ]
Huang, Jinliang [1 ]
Wang, Shufang [1 ]
Wang, Shiqian [2 ]
机构：
[1] Research Institute of Petroleum Exploration and Development, PetroChina, Beijing
[2] Exploration and Development Research Institute, Southwest Oil and Gasfield Company, PetroChina, Chengdu, 610051, Sichuan
来源：
Natural Gas Industry | 2014年 / 34卷 / 08期
关键词：
Early Cambrian; Graphitization; Marine shale; Organic rich; Play fairway identification; Resistivity; Response signature; Shale gas; Southern Sichuan Basin;
D O I：
10.3787/j.issn.1000-0976.2014.08.001
中图分类号：
学科分类号：
摘要：
Searching for some reliable evidences that can verify the carbonification of organic matters in marine shales is a major scientific issue of facing play fairway identification in old shale gas plays. Based on core, logging and testing data, an electric property correlation was performed between the two organic rich shale layers in the Lower Cambrian Qiongzhusi Fm and the Lower Silurian Longmaxi Fm in southern Sichuan Basin. The results were used to analyze the carbonification of organic matters in the Qiongzhusi Shale and its influence on gas storage in the shales. The following conclusions were obtained. (1) The electric properties verify the carbonification of organic matters in the Qiongzhusi Shale in the study area. The dry samples from this highly mature organic rich shale show a low resistivity, while showing an ultra-low resistivity on downhole logs. These resistivity values can be used to directly determine the degree of organic matter carbonification and the quality of source rocks. (2) In the Changning area, the Qiongzhusi Shale shows a low resistivity of dry samples and low to ultra-low resistivity on logs and the organic matters are seriously carbonized, while in the Weiyuan area, the Qiongzhusi Shale shows a basically normal resistivity and its degree of graphitization is between the Longmaxi and Qiongzhusi Fms in the Changning area. (3) The shale with a medium-to-high resistivity is remarkably better than that with an ultra-low resistivity in the respects of gas generation potential, matrix porosity and gas adsorption capacity. (4) Industrial gas flow was tested in the organic shales with a medium-to-high resistivity in the Jianwei-Weiyuan-Tongnan area in the north, where the Qiongzhusi Shale is a favorable shale gas exploration target.
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页码：1 / 7
页数：6
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