Open Access

ARTICLE

Gas Production and Reservoir Settlement in NGH Deposits under Horizontal-Well Depressurization

Lijia Li, Shu Liu, Xiaoliang Huang^*, Zhilin Qi

School of Petroleum Engineering, Chongqing University of Science and Technology, Chongqing, China

* Corresponding Author: Xiaoliang Huang. Email:

(This article belongs to the Special Issue: Subsurface Fluid Flow Dynamics and Applications in Carbon Reduction Technologies)

Fluid Dynamics & Materials Processing 2026, 22(1), 7 https://doi.org/10.32604/fdmp.2026.073294

Received 15 September 2025; Accepted 09 January 2026; Issue published 06 February 2026

Abstract

Identifying geohazards such as landslides and methane leakage is crucial during gas extraction from natural gas hydrate (NGH) reservoirs, and understanding reservoir settlement behavior is central to this assessment. Horizontal wells can enlarge the pressure relief zone within the formation, improving single-well productivity, and are therefore considered a promising approach for NGH development. This study examines the settlement response of hydrate-bearing sediments during depressurization using horizontal wells. A fully coupled thermal, hydraulic, mechanical, and chemical (THMC) model with representative reservoir properties (Shenhu region in the South China Sea) is presented accordingly. The simulations show that lower production pressures, while increasing gas output, also intensify formation settlement. The maximum difference in settlement between the lowest and highest production pressures reaches 0.016 m, contributing to more pronounced differential subsidence. Optimal well placement, specifically targeting a low-saturation hydrate zone containing free gas and situated adjacent to a high-saturation hydrate layer, markedly improves both gas production rate and cumulative yield, while reducing overall settlement and limiting changes in effective stress.

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Keywords

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