An Analytic Model for Analyzing the Effects of Dissociation of Hydrates on the Thermal Recovery of Heavy Oils

Abstract

Summary This paper presents an analytic model that includes the effects of the presence of hydrates in a thermal recovery process. The model considers continuous injection of steam into a reservoir containing an oil zone overlain by a hydrate zone. The model results indicate that, although part of the steam is consumed in dissociation of hydrates to gas and water and the dissociated hydrate zone acts as a thief zone for steam, there is a reduction in heat losses to the overburden because of the "insulation" effect of overlying hydrates. Thus, the net reservoir heat efficiency is not significantly affected by the presence of hydrates. Although the model does not address the effect of gas generated from hydrate dissociation, it is speculated that the dissolution of the gas will cause oil swelling, oil-viscosity reduction, and improved steamflood performance.