Cyclic methane hydrate production stimulated with CO₂ and N₂

Abstract

The cyclic methane hydrate production method was proposed with CO2 and N2 mixture stimulation. The cyclic production model was established based on actual hydrate reservoir parameters, accordingly, the production characteristics were analyzed, and a sensitivity analysis was conducted. The results show the following: (1) The depressurization mechanism is dominant in the cyclic production. CH4 production and CH4 hydrate dissociation can be greatly enhanced because the cyclic process can effectively reduce the partial pressure of CH4 (gas phase). However, there is a limited effect for CO2 storage. (2) Heat supply is essential for continuous hydrate dissociation. The CH4 hydrate dissociation degree is the highest in the near-wellbore area; in addition, the fluid porosity and effective permeability are significantly improved, and the reservoir temperature is obviously decreased. (3) The initial CH4 hydrate saturation, absolute permeability, intrinsic CO2 hydrate formation kinetic constant, injection time and production time can significantly influence the production performance of the natural gas hydrate reservoir.

Class-III Hydrate Reservoir Depressurization Production Enhancement by Volume Fracturing and Cyclic N2 Stimulation Combination

“… P – T phase equilibrium curves of CH 4 and N 2 hydrates 35 [reprinted (adapted or reprinted in part) according to Creative Commons Attribution License from Xia, Z.; Hou, J.; Wang, X.; Dai, X.; and Liu, M. Cyclic MH Production Stimulated with CO 2 and N 2 . Oil &Gas Science and Technology — Revue D’IFP Energies Nouvelles 2021 , 76 , 14.…”

“…Yasue et al 34 16 depressurization, thermal stimulation Alaska North Slope 17 CO 2 −N 2 gas mixture injection Eastern Nankai Trough 18,19 depressurization South China Sea 20,21 depressurization concluded that a higher N 2 concentration could enhance CH 4 production. In addition, our previous study 35 showed that pure N 2 injection was more effective than CO 2 /N 2 mixed gas from the perspective of CH 4 production.…”

“…carried out experiments on continuous N 2 /CO 2 gas mixture injection into hydrate-bearing cores with different hydrate saturations and concluded that a higher N 2 concentration could enhance CH 4 production. In addition, our previous study showed that pure N 2 injection was more effective than CO 2 /N 2 mixed gas from the perspective of CH 4 production.…”