An Engineering Approach To The Numerical Simulation Of A Huge Petroleum Reservoir
Authors: Johns M.L. , Holst P.H. 
Published: March 2010

This paper outlines the use of a computer data management system in describing a complex petroleum reservoir. Computer-accessible reservoir data files are shown to generate a technical advantage for engineers responsible for i11terpretation of reservoir performance. The importance of preliminary engineering studies designed to optimize layering criteria and grid orientation for reservoir simulation is demonstrated. These studies are shown to familiarize engineers with the interaction of petrophysical parameters and to identify potential simulation problems prior to field-scale numerical simulation. This paper illustrates the benefits which can be derived by the allocation of technical resources between engineering manpower and computers in the management of a petroleum reservoir.

Introduction

The Swan Hills Beaverhill Lake A & B Pool is located in north-central Alberta, as indicated in Figure 1, and is approximately 96,000 acres in areal extent. Swan Hills Unit No.1, the production entity discussed in this paper, encompasses 44,480 acres, as illustrated in Figure 2, contains 81.6 per cent of the pool's original oil-in-place of 1.9 billion stock tank barrels and contains 93.5 per cent of the pool's remaining recoverable reserves. The anticipated oil recovery factor for this unit, which is currently being waterflooded, is 48.6 per cent for an ultimate recoverable oil reserve of 761.0 million stock tank barrels. The productive horizon, a carbonate reservoir, is within the Swan Hills Member of the Beaverhill Lake A & B Pool. The producing horizon is subdivided into two geologicalentities, the Light Brown Lime and Dark Brown Lime members. The Light Brown Member, as indicated in Figure 8, represents the majority of the unit's productive capacity and recoverable reserves.

Oil production commenced with the pool discovery well located in Lsd. 08-11-68-10 W5M, in 1957. Subsequently, 282 production wells were drilled within the Swan Hills Unit No.1, which was unitized in January 1963. A waterflood pressure maintenance scheme was initiated within the western portion of the unit reef build-up area in mid-year 1963. Production activity was confined to this region by limited oil market demand until 1973, at which time water-flood operations were commenced throughout the remainder of the reef build-up area. The east reef platform commenced production during 1977. Cumulative oil production from Unit No.1 is 284.0 MMSTB or approximately 37 per cent of ultimate waterflood oil reserve.

Throughout the life of the reservoir, studies aimed at optimizing reservoir performance have been carried out. In order to further improve the management of the reservoir, a numerical reservoir simulation study was commissioned to more accurately determine the location and quantity of remaining recoverable oil. The study subsequently will aid in the selection of the optimum exploitation plan for the remaining reserves.

The value of an engineering study is very much dependent upon the accuracy and proper interpretation of the available data. In order to facilitate the interpretation of 1,600 individual open-hole log traces and conventional core analysis and detailed lithological information on 28,000 feet of full-diameter core, all Swan Hills data were placed on computer-accessible files.