Reservoir Description Through Pulse Testing in a Mature Field

Braisted, D.M. (Esso Australia Ltd.) | Spengler, R.M. (Esso Australia Ltd.) | Youie, R.A. (Esso Production Malaysia Inc.)

OnePetro 

Summary

Pulse testing was used within the Pulse testing was used within the Fortescue field to clarify reservoir geometries and fluid communication pathways within the field. The high pathways within the field. The high levels of communication demonstrated in the test data required a non-standard analysis of the pressure responses. In addition, proper attention to test planning, data acquisition and data planning, data acquisition and data processing allowed valuable insights processing allowed valuable insights into reservoir limits. Most of the structural implications deriving from the pulse tests have been subsequently supported by a recent 3D seismic survey over the area. The results and insights gained from these tests are being incorporated into a full field simulation model of Fortescue, which is an integral part of an ongoing depletion study of the field.

Introduction

The Fortescue field was discovered in 1978 and is one of Esso Australia and BHP Petroleum's mature oil fields in the Bass Strait offshore Victoria, Australia. Located 62 km offshore in 69 meters of water (Figure 1), the field is a separate oil accumulation in stratigraphic trap on the western flank of the Halibut and Cobia oil fields (Figures 2 and 3). In 1983, the Fortescue "A" and Cobia "A" platforms were installed to develop the field. Fortescue "A" is a 21 conductor platform designed to develop the central platform designed to develop the central and northern regions of the field. Eight wells from Cobia "A" were used for southern Fortescue development. Since production began in 1983, over 200 Mstb (32Mm3) of oil has been produced. The field is estimated to be produced. The field is estimated to be approximately 70% depleted at this stage.

The Fortescue reservoirs contain oil trapped between the marine shales deposited on the erosional unconformity at the top of the Latrobe Group and a base seal complex consisting of interbedded shales and coals, the FM-1.3C and M-1.0.1. It is this impermeable basal unit which hydraulically separates Fortescue from the Halibut and Cobia reservoirs.