An investigation of the fundamentals of combustion oil recovery

Abstract

Experimental work on the combustion-oil-recovery process has consisted of both laboratory and field studies. Although field experiments are the ultimate test of any oil-recovery process, they are costly, time consuming, and sometimes difficult to analyze quantitatively. Laboratory combustion-tube experiments can be operated far more rapidly and cheaply, but they are subject to scaling and interpretation problems. This study points out some of the more significant design problems and considerations important to the operation of the combustion tube and the interpretation of results. In this study an analytical heat model for the movement of a burning front axially along a cylinder with heat loss through an annular insulation was developed. The result was used to identify steady-state temperature distributions both ahead of and behind the burning front, with and without heat loss from the equipment. In addition, an application of this model enables the estimation of effective thermal diffusivity of hot, dry sand, the overall heat-transfer coefficient for the equipment, and the apparent thickness of the burning zone. A heat model was also developed for the steam-plateau phenomena associated with the combustion process. This model permitted estimation of the effective thermal diffusivity within the steam plateau. The results of 28 combustion tube runs have been used to verify the preliminary theory set forth by these two models in the region immediately ahead of and behind the burning front as well as the region within the steam plateau. The agreement between experimental laboratory temperature profiles and those computed by means of the two heat models was surprisingly good.