Publications

The Palaeocene WD Field is a complex stacked series of gas-bearing shallow marine and deep water turbidite reservoirs in a combination structural-stratigraphic trap. A key uncertainty is how to describe and model these reservoirs, as the 3D seismic dataset is ineffective in imaging reservoir geometries due to the effects of the thick, karstified limestone overburden. The objective is to describe some innovative techniques, aligned to an architectural element approach, to unlocking the resource potential at WD Field. An innovative approach to reservoir characterization has focused on building geological models using a hierarchical approach based on the detailed systematic description of >2000 ft of conventional core. These reservoirs are tied to a robust sequence stratigraphic framework that has integrated the surfaces identified in core with the nannofossil zonation scheme, but has additionally benefited from a unique analysis of the semi-quantitative geological description of ditch cuttings. Karoo Basin outcrop analogues have been instrumental in defining the temporal and spatial distribution of these reservoirs. Based on a chronostratigraphic scheme and detailed sedimentological and ichnofacies description of >2000 ft of conventional core, three key reservoir depositional systems have been recognised. These comprise an overall progradational systems tract, from basin floor lobes, through slope channel complexes to shelf edge deltas. The spatial distribution of these architectural elements is controlled by the relative position on the progradational clinoform wedge. Using analogue outcrop datasets from several different basins has allowed each depositional system to be assigned to architectural elements which can be mapped across the field. These 3-dimensional outcrop analogues is key to visualizing the subsurface, and aligned with the stacking patterns, provide the fundamental building blocks to unlocking the gas potential of the WD Field. The Palaeocene-aged reservoir depositional systems of the WD Field have not been published previously, and as such opens up a highly prospective play fairway in Bird’s Head region of West Papua. Additionally, the approach taken using reservoir depositional architectural elements, where there is no seismic image of the reservoir, is a novel approach to unlocking the gas potential of the WD Field.