Calculation of Oil Distilled During Steam Flooding of Light Crude
Authors: Sukkar Joseph K. 
Published: December 2007

This paper was prepared for the 41st Annual Fall Meeting of the Society of Petroleum Engineers of AIME, to be held in Dallas, Tex., Oct. 2–5, 1966. Permission to copy is restricted to an abstract of not more than 300 words. Illustrations may not be copied. The abstract should contain conspicuous acknowledgment of where and by whom the paper is presented. Publication elsewhere after publication in the JOURNAL OF PETROLEUM TECHNOLOGY or the SOCIETY OF PETROLEUM ENGINEERS JOURNAL is usually granted upon request to the Editor of the appropriate journal provided agreement to give proper credit is made.
Discussion of this paper is invited. Three copies of any discussion should be sent to the Society of Petroleum Engineers office. Such discussion may be presented at the above meeting and, with the paper, may be considered for publication in one of the two SPE magazines.

Abstract
It has been proposed that oil could be recovered by the injection of steam into a reservoir containing normal to light gravity crude oil. This process relies on the fact that when steam contacts the crude oil, a fraction of that oil is vaporized, is transported in the gas phase and condenses in the region where steam condenses. It is transported from there to the producing well as in a waterflood. Mathematical procedures for calculating the fraction of the oil which is evaporated from residual reservoir oil and the fraction which condenses with the steam are presented. A sample problem will also be presented.

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Theory and Procedure
When steam passes through a porous medium containing immovable oil, portions of the oil are evaporated and transported in the gas phase along with the steam. Crude oil is composed of many components having different volatilities and the areas in the reservoir from which the lighter components have been stripped by steam grow at a faster rate (velocity) than those from which the heavier components have been stripped. As the steam and vapors move forward, they eventually contact areas in the reservoir which are colder and condensation will occur. The velocity of the front at which all the steam condenses is slower than the velocity of the steam and can be calculated from heat balance equations. In this process, there are, therefore, three types of velocities to be considered; the velocity of the steam through the pores, V (this velocity may vary significantly in areas where heat losses are high), the velocity of the condensing steam front, Vc, and a series of velocities which describe the rate of advance, vi, of a front behind which a particular component in the crude has been depleted.
The method for calculating oil distilled during steam flooding consists of a procedure for calculating the vi/V ratios and Vc/V. It is reasoned that crude oil component having a velocity, vi, greater than the Vc would-be completely distilled and condenses at or beyond the leading edge of the steam front. Components having velocities, vi, smaller than Vc would be partially distilled. Figure 1 is an illustration that helps clarify the above statements.