Simultaneously improving ROP and maintaining wellbore stability in shale gas well: A case study of Luzhou shale gas reservoirs

Yaoran Wei; Yongcun Feng; Zhenlai Tan; Tianyu Yang; Shuang Yan; Xiaorong Li; Jingen Deng

Rock Mechanics Bulletin (Jul 2024)

Simultaneously improving ROP and maintaining wellbore stability in shale gas well: A case study of Luzhou shale gas reservoirs

Yaoran Wei,
Yongcun Feng,
Zhenlai Tan,
Tianyu Yang,
Shuang Yan,
Xiaorong Li,
Jingen Deng

Affiliations

Yaoran Wei: National Key Laboratory of Petroleum Resources and Engineering, China University of Petroleum, Beijing, 102249, China; College of Petroleum Engineering, China University of Petroleum, Beijing, 102249, China
Yongcun Feng: National Key Laboratory of Petroleum Resources and Engineering, China University of Petroleum, Beijing, 102249, China; College of Petroleum Engineering, China University of Petroleum, Beijing, 102249, China; Corresponding author. National Key Laboratory of Petroleum Resources and Engineering, China University of Petroleum, Beijing, China.
Zhenlai Tan: College of Safety and Ocean Engineering, China University of Petroleum, Beijing, 102249, China
Tianyu Yang: College of Safety and Ocean Engineering, China University of Petroleum, Beijing, 102249, China
Shuang Yan: National Key Laboratory of Petroleum Resources and Engineering, China University of Petroleum, Beijing, 102249, China; College of Petroleum Engineering, China University of Petroleum, Beijing, 102249, China
Xiaorong Li: National Key Laboratory of Petroleum Resources and Engineering, China University of Petroleum, Beijing, 102249, China; College of Safety and Ocean Engineering, China University of Petroleum, Beijing, 102249, China
Jingen Deng: National Key Laboratory of Petroleum Resources and Engineering, China University of Petroleum, Beijing, 102249, China; College of Petroleum Engineering, China University of Petroleum, Beijing, 102249, China

Journal volume & issue: Vol. 3, no. 3
p. 100124

Abstract

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The ROP (rate of penetration) within the horizontal section of shale gas wells in the Luzhou oil field is low, seriously delaying the exploration and development process. It is proved that reducing mud density mitigates the bottom-hole differential pressure (ΔP) and increases the ROP during overbalanced drilling. However, wellbore collapse may occur when wellbore pressure is excessively low. It is urgent to ascertain the optimal equilibrium point between improving ROP and maintaining wellbore stability. The safe mud weight window and the lower limit of mud density in the horizontal section of the Luzhou block are predicted using the piecewise fitting method based on conventional logging data. Then, the accuracy of the collapse pressure prediction was verified using the distinct element method (DEM), and the effect of wellbore pressure, in-situ stress, rock cohesion, and natural fracture density on borehole collapse was investigated. Finally, a fitting model of ΔP and ROP of the horizontal section in the Luzhou block is established to predict ROP promotion potential after mud density reduction. The field application of this approach, demonstrated in 8 horizontal wells in the Luzhou block, effectively validates the efficiency of reducing mud density for ROP improvement. This study provides a useful method for simultaneously improving ROP and maintaining wellbore stability and offers significant insights for petroleum engineers in the design of drilling parameters.

Published in Rock Mechanics Bulletin

ISSN: 2773-2304 (Online)
Publisher: KeAi Communications Co., Ltd.
Country of publisher: China
LCC subjects: Technology: Mining engineering. Metallurgy; Technology: Hydraulic engineering
Website: https://www.keaipublishing.com/en/journals/rock-mechanics-bulletin/

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