Reservoir Simulation Studies Reveal Key To Maximizing Waterflood Oil Recovery Virginia Hills Beaverhill Lake "A" Pool
Authors: Serra J.W. , Wilson R.C. 
Published: December 2007

PUBLICATION RIGHTS RESERVED PUBLICATION RIGHTS RESERVED THIS PAPER IS TO BE PRESENTED AT-THE 27TH ANNUAL TECHNICAL MEETING OF THE PETROLEUM SOCIETY OF CIM IN CALGARY, JUNE 7–11, 1976. DISCUSSION OF THIS PAPER IS INVITED. SUCH DISCUSSION MAY BE PRESENTED AT THE 27TH ANNUAL MEETING AND WILL BE CONSIDERED FOR PUBLICATION IN CIM JOURNALS IF FILED IN WRITING WITH THE TECHNICAL PROGRAM PUBLICATION IN CIM JOURNALS IF FILED IN WRITING WITH THE TECHNICAL PROGRAM CHAIRMAN PRIOR TO THE CONCLUSION OF THE MEETING.

Abstract
Two comprehensive simulation studies were performed on this reservoir to evaluate waterflood performed on this reservoir to evaluate waterflood performance to determine the long term production performance to determine the long term production and injection policy for the field. The results of these studies revealed that the key to maximizing economic oil recovery from the pool is to improve the vertical conformance of the waterflood.
This major biohermal reef reservoir is found at an average depth of 5600 ft. subsea and contains under-saturated crude oil in two partially overlying, non-communicating zones. Fifteen of the field's 117 wells were converted to water injectors in an irregular peripheral waterflood pressure maintenance scheme. The simulation models history matched 5 years of primary performance and 10 years of waterflood performance.
It was recognized at the outset that vertical conformance of the waterflood would be a dominant factor controlling reservoir performance. Since it was not practical to simulate the entire field in three dimensions, a four layer, two phase, three dimensional (3-D) reservoir simulation phase, three dimensional (3-D) reservoir simulation study was done on an area approximately representing the area of influence of the largest injection well. Results indicated that there was a degree of sublayering within the layers described in this model. Flood front saturation profiles from the history matched three dimensional model were employed in a unique method to derive pseudo relative permeability relationships for the two dimensional (2-D) areal model and an excellent history match of the performance of the entire pool was achieved. The performance of the entire pool was achieved. The study recommended a program of production logging to establish actual production/injection profiles. Results of subsequent attempts to workover wells to improve the flood profiles are discussed.

Introduction
It has been common practice in the oil industry for a number of years to conduct comprehensive reservoir engineering studies to design enhanced recovery schemes for oil reservoirs. A more recent very valuable use for in-depth reservoir studies is to optimize the performance of existing enhanced recovery schemes. Reservoir model studies on reservoirs which have considerable production history can be used to determine ways to improve performance through changes in production and injection policy, to justify remedial action to correct adverse performance, and to investigate the ramifications of alternate courses of action. Reservoir models can also be used as effective performance surveillance tools.
The opportunity to improve performance of an enhanced recovery scheme is greatest when the pool is unrestricted by market demand or other arbitrary rate restrictions because the full benefits of the changes can be realized as soon as the field responds to the change.
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