Predicting Compaction and Subsidence for an Immature Gasbearing Carbonate Field

Reservoir compaction and associated surface subsidence levels can be significant when high porosity carbonate gas reservoirs are depleted. A well known example is the Ekofisk field in the North Sea. Therefore these phenomena are incorporated when designing offshore platform constructions. Because the design and the construction part of development takes place well before the field production starts (i.e. when only little is known about the field), uncertainties exist in the parameters that are required for the prediction of surface subsidence. This paper describes the prediction of subsidence for the M1 field, offshore Sarawak, East Malaysia and shows that although many uncertainties may exist in the parameters required for the predictions, investigation into the effects of these uncertainties provides useful insight in the possible range of subsidence levels. The predicted range of subsidence levels can subsequently be used as input for the platform design.