A Numerical Study on Gas Production FromFormations Containing Gas Hydrates

摘要

Gas hydrates as a significant resource of natural gashave attracted considerable attention in the recent years.However, the severe environmental conditions of gashydrate reservoirs and the solid form of hydrates requireextensive technological development and expertise beforecommercial gas production becomes possible. Numericalstudies often give useful information in predicting thepotential and economic viability of a recovery process.This paper presents a 2-D cylindrical simulator forgas production from hydrate reservoirs. The modelincludes the equations of gas-water two-phase flow,conductive and convective heat transfer, and intrinsickinetics of hydrate decomposition. The simulator is usedto model a hydrate reservoir where the hydrate-bearinglayer overlies a free gas zone. A well is drilled andcompleted in the free gas zone. Pressure reduction in thefree gas zone leads to the decomposition of the overlyinghydrate and subsequent production of the generated gas. In this paper we investigate the effect of variousparameters on gas production behavior. In particular,these parameters relate to formation properties,operating conditions, kinetic parameters etc. Thecumulative gas generated and produced, pressure,temperature and saturation distributions are studied forthe different conditions. The potential of gas productionfrom formations containing gas hydrates is analyzedusing the results of the sensitivity study.