Quantitative evaluation and target adjustment of high-silica shale sections in Longmaxi Formation:A case from Block Z201 in southern Sichuan Basin
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TE132.2

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    Abstract:

    Zigong area of Sichuan Basin is the main battlefield of shale gas exploration in the Lower Silurian Longmaxi Formation. The test results of the first batch of horizontal wells deployed in this area are not ideal,and the average test production of a single well is only 7.6×104 m3/d. The test production of the latest batch of horizontal wells has been greatly improved by employing geology-engineering integration,conducting a comprehensive evaluation of target layers,and pointedly adjusting the target position. The following are the main research ideas for the quantitative evaluation and target adjustment of the high-silica shale sections of Longmaxi Formation in Zigong area. Firstly,the“sweet spot”layers are evaluated on the basis of geology-engineering integration,and Long11 sublayer is confirmed to be the best“sweet spot”layer for horizontal well deployment. Secondly,according to the classification standard of a high-silica shale section,Long11 sublayer is innovatively divided into an upper section,a medium section,and a lower section vertically. Fine reservoir evaluation is conducted mainly on the high-silica shale sections. It is clarified that the high-silica sections,with obvious advantages in gas-bearing property,brittleness,fracturing ability,etc.,can be used as the optimal target position. Thirdly,the single-well daily gas production after target adjustment is 20.01×104 m3/d,which is 2.6 times the value before target adjustment(7.64×104 m3/d). This result fully demonstrates that the carbon-rich and high-silica shale sections are the optimal solutions of target adjustment in this area. With the target adjustment direction of horizontal wells as the thread,this paper systematically expounds the reservoir conditions of the high-silica shale sections in the middle-low Long11 sublayer and increases the gas production by lowering the target position.

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HU Hao, ZHAO Wentao, ZHANG Aihua, FAN Tianyou, GUO Fufeng, ZOU Xiang, LIU Wenlei, CHEN Yi. Quantitative evaluation and target adjustment of high-silica shale sections in Longmaxi Formation:A case from Block Z201 in southern Sichuan Basin[J]. Petroleum Geology and Recovery Efficiency,2022,29(4):25~34

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  • Received:
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  • Online: January 12,2023
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