Application of Heat for Recovery of Oil: Field Test Results and Possibility of Profitable Operation

Abstract

Introduction Many have studied and experimented with the application of heat to oil sands in an effort to recover oil generally considered to be unrecoverable by conventional means. This interest is understandable because reduction of the viscosity of the oil or, better still, complete evaporation by application of heat seems to be promising and comparatively easy to achieve. The Worthington Corp., interested chiefly in secondary oil recovery equipment, and the Forest Oil Corp., a pioneer in secondary oil recovery methods, conducted a field test with heat injection and in situ combustion from Sept., 1953, until Aug. 1955. It was established that over 80 per cent of the oil in place could be recovered within that time. The tests were terminated when the oil production rate had fallen off to approximately 40 per cent of its maximum. In this paper methods and means will be described concerning how this result was achieved and what conclusions may be drawn from the pilot test data with respect to the economy of large scale operations. History of the Pilot Test, Preliminary Phase The test site chosen was Parker pool, near Casey, Ill. This reservoir showed poor primary production and a water drive test there covering an area of 17.5 acres was considered unsuccessful. Only 23,000 bbl were recovered in five years from this area. The conditions found in the Pennsylvania sand formation are presented in Table 1. These conditions are typical of many smaller Mid-western pools, although this oil sand is exceptionally shallow. This shallowness was considered an advantage for a first test of this kind. The pressure to be applied was low and so were the development costs. Also, in case of troubles with the injection and production wells, corrective measures would have been less costly. A power and heat producing pilot unit suitable for the above listed conditions was built early in 1952 and shipped to the test site, where tests began on Sept. 1, 1953. This equipment has been described previously. It produced a combustion gas-air-steam mixture at maximum pressure of 500 psi, at a maximum temperature of 1,000°F, at a maximum rate of 25 tons per day. Pressure, temperature, and product quantity could be varied in wide range. Also, the composition of the gas-steam mixture could be varied from 100 per cent stir with 23 per cent oxygen by weight to a combustion gets steam mixture containing 53.4 per cent steam, 41.0 per cent nitrogen, 6.6 per cent carbon dioxide, and practically no oxygen.