The Combustion Recovery Process Principles And Practices
Authors: Dingley A.J. 
Published: December 2007

This paper was to be presented at the California Regional Meeting of the Society of Petroleum Engineers of AIME, to be held in Bakersfield, Calif., Nov. 4–5, 1965. Originally it was presented at the 16th Annual Technical Meeting of the Canadian Institute of Mining and Metallurgy, P. and N. G. Division, held in Calgary, Alta., May 5–7, 1965, and the Society of Petroleum Engineers of AIME gratefully acknowledges permission to present this paper as well as to preprint it. Permission to publish in any form must be secured from the Petroleum Society of C. I. M.

The reservoir mechanics of a combustion drive are complex, involving: a fluid displacement, a heat transfer and a chemical reaction. Air is injected continuously into the correlations formation, and the oil around the injection wellbore is ignited. This ignition can be achieved spontaneously when the oil oxidizes rapidly, or it can be induced by preheating the air to a high temperature just prior to its entering the formation. A common displacement-combustion front is then moved through the reservoir towards the producing wells. This process is known as forward combustion. In the reverse combustion process, oil around the production wells is ignited and the combustion front is moved countercurrent to the air injection.

When considering the applicability of the combustion recovery process to a specific reservoir, the first step should be the rough estimation of performance based on data from various correlations of reservoir and fluid properties. If this is encouraging, laboratory burning tests should then be carried out. These consist of packing a steel tube with core material containing reservoir and fluids in their correct proportions. A burning front is passed through this pack. Data obtained from this experiment enable the fuel deposit and unit air requirement to be calculated.

The areal sweep efficiency likely to be achieved in the reservoir can be obtained from potentiometric model data. The fuel deposit data obtained in the laboratory enable the displacement efficiency to be calculated; and so, having estimated the invasion efficiency, it is possible to calculate the oil recovery from the swept zone. The average oil displacement rate can then be calculated by relating the unit oil recovery, the unit air requirement and the air injection rate. The injection pressure requirement for a given air injection rate can be estimated from flow formulas. However, the best method is to run an injection test in the field.

The above calculations will yield sufficient information for an assessment to be made of the feasibility of the combustion recovery process as a means for improving the recovery from the reservoir in question. The results of the calculations can then be incorporated into the design of a pilot installation. This pilot can be viewed as the first stage of a field-wide development, since it is usual to develop areas of the field in sequence to reduce the initial compressor plant cost and to utilize this plant to its fullest. The injection, production and operating data, obtained from the pilot, can then be used in the usual manner to design the fieldwide development of the project.