Title: The maximum installation depth for a pre-drilled liner with floating inner tubing in horizontal well in tectonically deformed coal seams

Authors: Yansen Bi; Deli Gao; Baoan Xian

Addresses: MOE Key Laboratory of Petroleum Engineering, China University of Petroleum, Beijing, No. 18, Fuxue Road, Changping District, Beijing, China ' MOE Key Laboratory of Petroleum Engineering, China University of Petroleum, Beijing, No. 18, Fuxue Road, Changping District, Beijing, China ' Institute of Resource & Environment, Henan Polytechnic University, No. 2001, Shiji Road, Shanyang District, Jiaozuo, China

Abstract: A horizontal completion technology of outer liner with inner tubing has been proposed to solve the problems of wellbore collapse, friction resistance and sticking in tectonically deformed coal seams. However, there is no study on the maximum installation depth of this dual-pipe structure. First, a hydraulic model of dual annulus is established to calculate the hydraulic parameters and interpret the influencing factors. Second, a quantitative prediction model of maximum installation depth for the pre-drilled liner with floating inner tubing (PL&FIT) is deduced by coupling mechanics and hydraulics. At last, a horizontal well is taken to calculated the installation depth of PL&FIT by finite difference method. The results indicate that the maximum installation depth of the PL&FIT adopts maximum reach limited by mechanics or hydraulics, which depends on the dual annulus equivalent diameter ratio (λ). The maximum reach envelope is deduced for the PL&FIT. [Received: 28 October 2022; Accepted: 2 September 2023]

Keywords: CBM; horizontal well; dual-pipe structure; tubing floating; liner installation depth limit.

DOI: 10.1504/IJOGCT.2024.136542

International Journal of Oil, Gas and Coal Technology, 2024 Vol.35 No.2, pp.159 - 181

Received: 27 Oct 2022
Accepted: 02 Sep 2023
Published online: 06 Feb 2024 *

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