The Jabiru field forms part of a northeast-southwest trending complexly faulted, structural high. Massive marine sands of Juassic age and of excellent quality are truncated by two unconformity surfaces. The 60 m oil column is underlain by an extensive aquifer which provides strong bottom-water drive. The field came on stream at 2100 m3/d in August 1986 and is currently producing through two subsea wells to a floating production facility at a rate of 4540 m3/d. Two further wells are planned to come on stream by mid-1988, increasing field potential to about 8740 m3/d.
Reservoir simulation has played a key role in the development of the Jabiru field. Initial models ranged from 2-dimensional/2-phase radial to 3-dimensional/2-phase cartesian, to allow preparation of and increase confidence in forecasts of field behavior. The most serious limitations of these simulations lay in the geological models used and the prediction of water breakthrough.
This paper is intended as a case history discussing the evolution of the reservoir simulation models through five significant revisions and compares the results obtained at each stage. The variation of model parameters is presented always with the aim of understanding a complexly faulted reservoir experiencing strong bottom-water drive. Different solution methods and gridding options have been employed and emphasis is placed on the need to be judicious when applying several simulator options concurrently. In particular the use of segregated flow and the relative merits of placing a finer grid around wells to model the coning behavior are discussed.
This paper is aimed at the practicing reservoir engineer and, by frankly outlining the route undertaken by BHP Petroleum, some of the pitfalls and problems as well as benefits of reservoir simulation are exemplified.