Performance Of Five-Spot Water Floods In Stratified Reservoirs Using Streamlines
Authors: Higgins R.V. , Leighton A.J. 
Published: December 2007

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This paper is to be presented at the Seventh Annual Meeting of Rocky Mountain Petroleum Sections of AIME May 25–26, 1961, in Farmington, N.M., and is considered the property of the Society of Petroleum Engineers. Permission to publish is hereby restricted to an abstract of not more than 300 words, with no illustrations, unless the paper is specifically released to the press by the Editor of JOURNAL OF PETROLEUM TECHNOLOGY or the Executive Secretary. Such abstract should contain conspicuous acknowledgment of where and by whom the paper is presented. Publication elsewhere after publication in JOURNAL OF PETROLEUM TECHNOLOGY or SOCIETY OF PETROLEUM ENGINEERS JOURNAL is granted on request, providing proper credit is given that publication and the original presentation of the paper.

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Many contributions to methods of forecasting the performance of waterfloods of a five-spot pattern have been made by investigators. In most of these forecasting methods, a previously selected sweep efficiency is used, and other simplifying assumptions are employed to obtain the objective. In this paper the calculated oil recoveries from several five-spot single-and multiple-layer stratified reservoirs were made with a minimum of assumptions, and because of the techniques used, no previously selected sweep efficiency was required. Permeability curves and continuously changing saturation gradients are used in every section of the pattern. By means of a potentiometric model, the flood pattern is divided into channels, the centers of which are the streamlines. The channels are divided into cells. As flood water enters, the permeability and saturation of each cell change with time.

The results of the calculations starting in primary phase agree with performance of laboratory five-spot waterfloods reported in the literature. No comparable laboratory data are in the literature for waterfloods starting in the secondary phase.

In this study the production from multiple sand layers of different absolute permeability but with the same relative permeability-saturation relations are combined. The results are shown for a single- and ten-layer reservoir with a permeability variation of 0. 60. The oil rate, water-oil ratio, and recovery are shown as functions of time for a 2- and 20- centipoise oil starting in primary phase and after "fill-up."

In appraising potential waterfloods, the reservoir engineer necessarily makes many simplifying assumptions because of the complicated nature of the many factors affecting their performance. This report presents the calculated performance of a five-spot waterflood in stratified reservoirs using only one assumption, namely, that there is no cross flow between channels. However, the effect of cross flow on the calculated performance of a five-spot pattern is virtually negligible as is shown in the discussion of its effect in the "Commentary" section of this report.