Facies Modelling and Hydrocarbon in Place Estimation Using Numerical Sequence Stratigraphy in Talang Akar Formation, Intan Field, Offshore Indonesia

The Asri Basin is a potential hydrocarbon reservoir in Indonesia. However, the complexity of the geologic structure and stratigraphy of the basin posed a challenge in accurately estimating the hydrocarbon reserve. Furthermore, oil is trapped by an anticlinal structure that tends to occlude a direct penetration of appraisal wells into the formation.

In this work, a numerical sequence stratigraphy modelling approach is used in the characterisation of sedimentary facies in the Talang Akar Formation. A volumetric technique is then applied to estimate the hydrocarbon in place. First, sandstones in the study interval were divided into several lithofacies: bioturbated-fine Sandstone, paralel lamination-fine sandstone, crosslamination-medium sandstone, paralel lamination-coarse sandstone and crossbedding – coarse sandstone. Then, a volumetric estimation of the oil in place; using net sand mapping and net pay discretisation, was derived from the model yielding a total reserve of 18 million barrels of oil (18 MMBO).