| Popis: |
The offshore Scarborough gas field in Western Australian’s Carnarvon Basin was discovered in 1979 by the Scarborough-1 well. The field contains about 16 trillion cubic feet original gas-in-place (OGIP) of dry gas. It has been appraised by an additional four wells and the 2004-vintage HEX03A 3D seismic survey. Concepts are currently being evaluated for the field’s development. The field is contained within a large, 800 square-kilometre, very low-relief faulted anticline. The reservoir interval comprises deep water deposits, is divided into a high-quality, high net-to-gross Lower Fan, overlain by lower net-to-gross Middle Fan and Upper Fan. The field is expected to have strong flank and bottom-water drives. The development concepts being considered have minimal tolerance for water production; as such water production is expected to be managed via well shut-ins. Given the low relief of the structure, a significant factor in characterising reservoir performance will be the effect of stratigraphic baffles at various scales, on water movement. Static reservoir models for the Scarborough field were built to incorporate deepwater stratigraphic concepts derived from a plethora of basin-floor fan subsurface and outcrop analogues. These concepts have been applied with systematic distribution of depositional facies, including siltstone baffles bottom-loaded at multiple hierarchical levels. Dynamic simulation models were built to investigate the sensitivity of sweep efficiency, timing of water arrival and ultimate recovery on a number of key static model parameters. The parameters that were evaluated included: 1) the effect of reduced stratigraphic organisation; 2) the partial removal of baffles at varying stratigraphic levels; 3) the lateral extent and continuity of baffles; and 4) the vertical permeability of siltstones. The success of the study was facilitated through the effective workings of an integrated, multidisciplinary team of geoscientists and engineers, who maintained frequent communication and feedback through the modeling process. |
