Numerical Investigation on Gas Production Performance in Methane Hydrate of Multilateral Well under Depressurization in Krishna-Godavari Basin

Xin Xin,Yilong Yuan,Si Li,Tianfu Xu,Bo Li

doi:10.1155/2021/9936872

Abstract

Nature gas hydrate is a new kind of clean and potential resources. Depressurization is regarded as the most effective and promising hydrate production technology. One of the key points in improving the gas production effectiveness of depressurization is whether pressure gradient could transmit in strata effectively. Single well method is widely used in hydrate exploit which is circumscribed in expanding the range of hydrate decomposition. Consequently, the well structure and production strategy needs to be optimized for improving the gas recovery efficiency. The multilateral well technology is proposed for increasing the gas productivity of the reservoir greatly by increasing the multilateral branches. In this paper, we established a numerical simulation model based on the geological data NGHP-02-16 site in the KG basin to evaluate the gas production performance of the reservoir by depressurization. It mainly focuses on investigating the gas production performance of multilateral wells with different combinations of geometric parameters of multilateral branches, such as different dip angle, numbers, and spacing of lateral branches. The result shows that the multilateral well method can effectively increase the gas production rate with the water production rate increase slightly. The cumulative gas production volume of a single vertical well is about 2.85 × 10 6 m 3 , while it is of the multilateral well can reach 4.18 × 10 6 m 3 during a one-year production. The well interference, the effective influence radius of each multilateral branch, and the vertical depth of the lateral branch are the main factors which affect the gas production efficiency of the multilateral well. The optimization of the geometric parameters of lateral should consider not only the gas production efficiency but also the well interference between the lateral branches.

Highlights

Nature gas hydrate (NGH), an ice-like crystalline compound, can exist steadily in low-temperature and high-pressure conditions [1, 2]
We developed the multilateral well models based on the single vertical well to investigate the effect of geometric parameters and emplacing manners of production interval on the production performance
Numerical simulations were used to evaluate the gas production performance of the reservoir by depressurization based on the geological data acquired during NGHP02 from National Gas Hydrate Program (NGHP)-02-16 site in the KG basin

Summary

Introduction

Nature gas hydrate (NGH), an ice-like crystalline compound, can exist steadily in low-temperature and high-pressure conditions [1, 2]. This gas hydrate molecule consisting of a lattice of one type of molecule trapping and containing a second type of molecule (such as CH4, C2H6, C3H8, and C4H10). At standard pressure and temperature, a methane hydrate molecule contains approximately 160 volumes of methane for each volume of water [3, 4] This energy is regarded as a clean and potential resources. The depressurization method is promoting the methane hydrate dissociation into gas and water by decreasing the local pressure of the layer below the phase equilibrium curve of gas hydrate [10]. Enlarge the area of depressurized discharge is one of the key factors in increasing the gas production efficiency [12]

Results

Discussion

Conclusion