Evaluation on the gas production potential of different lithological hydrate accumulations in marine environment

Abstract

In this work, the marine hydrate deposits were classified into CHR (clay reservoir), SIHR (siltstone reservoir) and SHR (sandstone reservoir) according to the grain sizes of the sediments. Based on field measurements and proper estimations in Shenhu area, the gas production potentials of these different lithological hydrate reservoirs were numerically studied through Tough + Hydrate. The simulation results reveal that SHR can provide the most desirable gas production potential with the following superior features: (a) a burst gas release at initial stage of the production; (b) the highest average gas release rate 1.7 × 103 ST (standard temperature) m3/d; (c) the highest total release gas volume 1.7 × 107 ST m3, (d) the highest gas-to-water volume ratio with an average value of 9.04. However, the evolution of the spatial distributions of the characteristic parameters indicates that the gas production in SHR has met some challengeable problems in both technology and environment aspects. On the other hand, compared with CHR, SIHR shows a higher gas release rate and cumulative volume but a worse gas-to-water volume ratio during the entire production period. In addition, the evolution of the salinity spatial distribution indicates an unsatisfactory impact on the environment in the later stage of production for SIHR.