Field Application of a Computer Waterflood Model

Abstract

American Institute of Mining, Metallurgical, and Petroleum Engineers, Inc. This paper was prepared for the 43rd Annual Fall Meeting of the Society of Petroleum Engineers of AIME, to be held in Houston, Tex., Sept. 29-Oct. 2, 1968. 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 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. 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 This paper covers the application of a two-dimensional computer waterflood model to the South Glenrock "B" Unit waterfloods. The study had a twofold objective:to match past performance of the waterflood to determine past performance of the waterflood to determine the present location of the flood fronts, andto make predictions of future behavior under various plans of operation to evaluate operating procedures that would maximize oil recovery procedures that would maximize oil recovery from the field. The reservoir was modeled by overlaying the field map with a suitably sized mesh to divide the reservoir into small cells. The permeability and capacity of the cells were permeability and capacity of the cells were assigned from well data. Once the reservoir size and capacity were modeled, the performance matching runs were made. The actual field performance was divided into tune increments, performance was divided into tune increments, wherein the injection and production rates could be approximated by steady-state conditions. The pressure distribution in the reservoir was calculated, based on the Laplacian equation for two-dimensional, slightly compressible flow. Once the pressure distribution was calculated for the reservoir, the velocity and front tracking calculations were made. The new front locations at the end of each time period were determined and checked with actual production history. The process was then repeated with new rates for the next time step, until the present flood front positions were determined. To achieve maximum flood sweep of the reservoir, prediction runs were made varying both the injection rates and pattern until the optimum floodout was obtained. Conclusions from the study are:that it is both possible and practical to model a major waterflood, andthat through a reservoir study of this type, a waterflood can be surveyed periodically to achieve maximum flood performance. Periodic updating of the study performance. Periodic updating of the study will point out areas where changes are required before they become major problems. Introduction The study of the South Glenrock "B" Unit waterflood was undertaken to establish the current status of the flood and what steps, if any, might be taken to improve the flood performance. To this end, a computer program performance. To this end, a computer program based on the work of McCarty and Barfield, was used both to match past performance and to make predictions of pattern behavior under various predictions of pattern behavior under various modes of operation. The South Glenrock field is comprised of three reservoirs, all or some of which are producing over various portions of the field. producing over various portions of the field.