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Calculation of Micro-hole Collapse Pressure in Gas Shale |
YUAN Junliang1, DENG Jingen1, LI Dahua2, CHENG Lijun2, YAN Wei1, HU Lianbo1, LIN Hai1 |
1. State Key Laboratory of Petroleum Resources and Prospecting, China University of Petroleum, Beijing, Beijing 102249, China;2. Chongqing Municipal Bureau of Land and Resources, Chongqing 400042, China |
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Abstract: Drilling and exploitation of the gas shale is just in an initial stage in China. Drilling practice shows that drilling accidents are frequent, and major cause is wellbore instability. From the experience of the shale-gas drilling in North America, and the casing programs in Sichuan Basin and Haynesville, it is shown that the drilling accidents can be reduced by the decrease of the size of the borehole. Based on the size effect theory, the advantages and disadvantages of different size effect models are compared. The Vutukuri's model is chosen to analyze the micro-borehole surrounding rock strength and the Mclamore's anisotropic failure prediction model is adopted to demonstrate the strength anisotropy of the shale. Based on the collapse pressure prediction model, the collapse pressure of a normal borehole and a micro-borehole in the bedding formations are calculated, respectively, furthermore, the trajectory sensitivity analysis is also conducted. The collapse pressure changes with the well declination are also considered. Comparing the difference between the two sides, it is shown that the micro-borehole can significantly reduce the collapse pressure by approximately 10%, therefore reduce the shale-gas drilling accidents.
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Received: 14 November 2012
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[1] |
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[2] |
WU Qingyun, ZHENG Meng, HU Yunxia. Shale Gas Produced Water Contamination and Its Comprehensive Treatment[J]. journal1, 2014, 32(13): 74-83. |
[3] |
CHEN Qiao, TAN Yanhu, WANG Lisha, WANG Sen, LIAO Kaigui, LIU Hong, YAO Guanghua, WANG Qijun, YANG Bo. Reservoir Physical Characteristics of Shale Gas in Longmaxi Formation in Southeastern Chongqing[J]. journal1, 2013, 31(36): 15-19. |
[4] |
SONG Ning;YANG Shuaishuai;HOU Pengfei;GUO Haiying;WANG Guangli. Geological Conditions of Shale Gas in the Wufeng-Gaojiabian Formations in Lower Yangtze Area[J]. , 2013, 31(33): 42-46. |
[5] |
FANG Dazhi. Key Factors of Shale Gas Development[J]. , 2013, 31(31): 70-74. |
[6] |
CAI Hua;FU Suiyi;CHENG Shiqing. Production Decline Mode for Fractured Shale Gas Reservoirs with Stress Sensitivity[J]. , 2013, 31(24): 51-54. |
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