Abstract

This paper presents a method for estimating field fuel consumptions by adjusting laboratory in-situ combustion fuel consumption data for the effects of formation porosity and permeability. permeability. Results from combustion experiments were used to establish the reaction kinetic and heat loss parameters in an in-situ combustion model. After attaining satisfactory agreement between calculated and experimental results, both for unconsolidated and consolidates media, the model was used to calculate the effects of changes in porosity and permeability on the fuel consumption. Calculations were made for a wide range of crude oil viscosities. The study showed that porosity and permeability have marked effects on fuel consumption, and that these effects depend on the crude oil viscosity.

Introduction

In-situ combustion has become an important process for oil recovery. Successful process for oil recovery. Successful engineering of one of these projects depends on the estimate of the fuel concentration, which determines air requirements for propagation of the combustion front. Air requirements can critically affect the technical and economic prospects for an installation. prospects for an installation. Because of the importance of fuel concentration to the process, many studies aimed at correlating fuel with the various chemical physical and operating parameters of the physical and operating parameters of the system have been made. These attempts have not produced generally applicable correlations. Consequently, current practice in estimating fuel for a particular field prospect involves laboratory experimentation to characterize the system. Commonly a combustion tube run provide an estimate of the fuel concentration under laboratory conditions. This value may be corrected for various field operating condition which differ from those in the laboratory, such as pressure or gas flux.

Two parameters which should affect the fuel, but whose effects have been treated only briefly in the literature, are permeability and porosity. Alexander, Martin and Dew found that porosity. Alexander, Martin and Dew found that with a 21.8 degrees API crude oil., crushed Curtis core gave essentially the same fuel availability as consolidated Crutis core, and that an Ottawa sand pack gave essentially the same fuel availability as a consolidated Berea core. Moss, White and McNiel presented two combustion tube runs which gave fuel values closely comparable to field test results. Theoretical papers make no direct mention of the effects papers make no direct mention of the effects of permeability and porosity on fuel concentration.

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