Open Access

ARTICLE

Numerical Investigation of Combined Production of Natural Gas Hydrate and Conventional Gas

Hongzhi Xu^1,2, Jian Wang^1,3, Shuxia Li^1,*, Fengrui Zhao¹, Chengwen Wang¹, Yang Guo¹

1 School of Petroleum Engineering, China University of Petroleum (East China), Qingdao, 266580, China
2 CPOE Research Institute of Engineering Technology, Tianjin, 300451, China
3 CNPC Offshore Engineering Company Limited, Beijing, 100028, China

* Corresponding Author: Shuxia Li. Email:

(This article belongs to the Special Issue: Solid, Fluid, and Thermal Dynamics in the Development of Unconventional Resources )

Fluid Dynamics & Materials Processing 2024, 20(3), 505-523. https://doi.org/10.32604/fdmp.2023.030604

Received 14 April 2023; Accepted 27 June 2023; Issue published 12 January 2024

Abstract

Natural gas hydrate (NGH) is generally produced and accumulated together with the underlying conventional gas. Therefore, optimizing the production technology of these two gases should be seen as a relevant way to effectively reduce the exploitation cost of the gas hydrate. In this study, three types of models accounting for the coexistence of these gases are considered. Type A considers the upper hydrate-bearing layer (HBL) adjacent to the lower conventional gas layer (CGL); with the Type B a permeable interlayer exists between the upper HBL and the lower CGL; with the type C there is an impermeable interlayer between the upper HBL and the lower CGL. The production performances associated with the above three models are calculated under different conditions, including only a depressurized HBL (only HBL DP); only a depressurized CGL (only CGL DP); and both the HBL and the CGL being depressurized (HBL + CGL DP). The results show that for Type A and Type B coexistence accumulation models, when only HBL or CGL is depressurized, the gas from the other layer will flow into the production layer due to the pressure difference between the two layers. In the coexistence accumulation model of type C, the cumulative gas production is much lower than that of Type A and Type B, regardless of whether only HBL DP, only CGL DP, or HBL + CGL DP are considered. This indicates that the impermeable interlayer restricts the cross-flow of gas between HBL and CGL. For three different coexistence accumulation models, CGL DP has the largest gas-to-water ratio.

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Keywords

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