Publications

A stratigraphic model is described for Western Irian Jaya that highlights the Permian, Triassic, and Early to Middle Jurassic as favorable times for the development of sandstone reservoirs. In addition, other periods with significant sandstone deposition include a regressive sequence in the Late Cretaceous to Early Tertiary, a short period within the Late Oligocene, and a relatively recent but potentially thick sequence in the Pliocene. In the older, Late Palaeozoic to Early Mesozoic sections not enough is known about faulting that is thought to have occurred in two or three phases (Permian?, mid-Triassic and Early Jurassic), and which is expected to have controlled deposition. The Late Cretaceous to Paleocene and Late Oligocene sands were deposited during a prolonged period dominated by carbonate sedimentation. The sources of these sand and nature of any potential seals are considered, as well as the erosional effects of a regional unconformity that map have removed the older of these two sequences. The Pliocene sands were rapidly deposited in new Basins controlled by a widespread tectonic change. The textural and mineralogical maturity and distribution of these young sands is an important consideration in evaluating reservoir potential.