Deep Water Reservoir Architectural Elements of the Wiriagar Deep Paleocene Field, Papua Barat

The Wiriagar Deep Field was discovered in 1994 by Atlantic Richfield with the WD-1 exploration well, which encountered gas-bearing reservoirs of both Paleocene and Jurassic age. Seven subsequent appraisal wells have been drilled across the 600km2 Wiriagar Deep structure. The Paleocene-aged Daram Formation reservoirs are a complex stacked series of gas-bearing deep water turbidite reservoirs in a combination structural-stratigraphic trap. A key uncertainty in the Wiriagar Deep Paleocene field is how to describe and model the geometry and distribution of these stacked deep water reservoirs, as the current 3D seismic dataset is ineffective in imaging the reservoir due to the effects of the overlying thick massive karstified limestone of the Faumai Formation. Additionally, detailed correlation of individual sands is difficult given the current well spacing of ~5km. Consequently, the approach taken has been to focus on the geological models using a hierarchical approach based on detailed systematic description of the extensive conventional core database across the Wiriagar Deep Paleocene Field. Based on core description, the Paleocene consists of ten lithofacies which reflect deposition from four types of deep water processes: the deposits of highand low-density turbidity currents, debris flow deposits, hemipelagic mud and hybrid deposits. Two key reservoir architectural elements have been defined from leveed channels to basin floor lobes. The spatial distribution of these architectural elements is controlled by the relative position on the progradational clinoform wedge. Using analogue outcrop exposures from several basins has allowed each architectural element to be mapped across the field. These dimensional geological datasets are key to visualizing the subsurface, and are the fundamental building block to unlocking the potential of the Wiriagar Deep Paleocene Field.