Gas Hydrates Extraction by Swapping-Depressurisation Method

Abstract

Gas Hydrate, one of the unexplored domains in the energy sector has a vast potential to quench the future energy demands. Depressurization, Thermal Stimulation, Carbon swapping and Inhibitor injection are a few processes involved in its production. These techniques are environmentally degrading as uncontrolled dissociation of Gas Hydrates takes place. The paper focuses on an unexplored but a sustainable technique to extract gas hydrates. When depressurization along with CO 2 swapping methods are used simultaneously in two adjacent wells, then these both methods results in a continuous flow of CH 4 in both wells through surface and sub-surface reservoir. They acts as counterparts of each other and diminishes each other's limitations that are being faced when used individually. So, this method could be a future technique to efficiently and economically extract methane from its clathrate. The paper also discusses the well modeling required to implement this technique and simultaneously increasing the amount of methane hydrates exposed, overcoming the permeability issues by using Depressurization method along with CO 2 swapping through injectors and producers creating a continuous cyclic process of swapping and production. In the proposed method, two adjacent wells are used as producer and injector well, at injector swapping method is employed and at producer well depressurization method is employed. Relevant issues along with well modeling and advantages are also discussed in the paper.

Study on the Influence of Pressure Reduction and Chemical Injection on Hydrate Decomposition

“…Li S X et al [19] and Bai Y H et al [20] found through physical and numerical simulations, that although the combined method of heat injection and depressurization can effectively improve energy utilization, long-term depressurization may lead to reservoir instability. Gupta et al [21] found that the depressurization and CO 2 replacement method is efficient and economical, and can effectively solve the permeability problem, but this method must strictly limit the large amount of CO 2 overflow, so it has extremely high technical requirements and is not suitable for conventional mining. The combined method of depressurization and ground decomposition can easily cause formation instability due to the instability of shallow hydrate reservoirs on the seabed and the simultaneous action of pressure drop and shallow mining, so the mining efficiency of this method is low.…”

A Thermal Chemical Reaction System for Natural Gas Hydrates Exploitation

“…Their research results showed that the replacement efficiency increased from approximately 64-85% (Kph et al, 2012). In practice, the above methods are combined to obtain better results, e.g., electric heating-assisted depressurization, CH 4 -CO 2 replacement-assisted depressurization, and co-injection of the inhibitor and CO 2 (Li et al, 2010;Gupta and Aggarwal 2014;Minagawa 2015;Khlebnikov et al, 2017). Accordingly, we propose a thermochemical reaction to utilize both the heat generated by a thermochemical reaction to provide heat for NGH decomposition and the gas generated by the thermochemical reaction to replace the methane in NGHs.…”