Enhanced gas production from clayey-silt hydrate reservoirs based on near-well reservoir reconstruction using the high-pressure jet grouting technology.

Over 90% of the global hydrate resource is accumulated in the fine-grained sediments with very low permeability. Gas production from the low-permeability hydrate reservoirs is significantly restricted by the effective transport of fluids into the production well. To improve gas production from the low-permeability hydrate reservoirs, the high-pressure jet grouting (HPJG) technology is first proposed that involves construction of an artificial jet grouting column (JGC) with relatively high-permeability around the production well using the cellular concrete. In this work, the main target is to investigate the feasibility of this proposed method for enhancing gas production by numerical simulation, aiming at the clayey-silt hydrate reservoirs in the Shenhu area of South China Sea. It is demonstrated that the hydrate dissociation efficiency and the gas productivity greatly improved by about 157% and 110%, respectively, by constructing an artificial JGC with radius of 0.5 m around the production well. The results suggest the proposed method is a promising strategy for enhancing gas production from the low-permeability hydrate reservoirs. This is mainly because the artificial JGC significantly promotes the advance of depressurization and the transport of gas and water within the reservoir. In addition, gas production performance of the proposed strategy mainly depends on JGC radius and JGC height, while the JGC porosity has less effect. For the specified clayey-silt hydrate reservoirs in the Shenhu area, the artificial JGC radius, height, and permeability are recommended as 0.5 m, 30 m, and 1.0 × 10 ⁻¹² m², respectively. [Display omitted] • The jet grouting method is first proposed to enhance hydrate production. • The feasibility of the novel hydrate production strategy is investigated. • The uncertain and adjustable parameters are evaluated in detail. • The optimal parameters are designed for the clayey-silt hydrate reservoirs. [ABSTRACT FROM AUTHOR]