Publications

In late 2004, ConocoPhillips began to develop the idea that a basin straddling the Australia-Indonesia international border may contain a Paleozoic petroleum system. Known as the Arafura basin, this virtually unexplored basin sits within the northwest corner of the Australian continental margin. In 2006, COP gained an interest in three blocks in the basin, one in Indonesia (Amborip VI PSC) and two in Australia (NTP74 and NTP75). New seismic data did not reveal valid structures in the Australian blocks which were subsequently relinquished, but the work program for the Indonesian PSC continued through to the exploration phase. Following additional study in 2008 the Arafura Sea PSC was also acquired by COP in Indonesia. After farming out to partners TOTAL and OPIC, two wells were drilled, one in each block, in early 2011. The targets were two large 4-way dip closed anticlines. Previous work in the industry led many to believe that the area was a platform composed entirely of Proterozoic and older rocks. However the well results prove the existence of a thick, extensive succession of lower Paleozoic rocks is present across the Arafura Basin. Exploration in this area was challenging due to the remoteness of the drill sites, lack of nearby well control, and logistical and safety challenges. There was no functioning oil industry infrastructure in the region and no marine shore bases equipped to support the operations. All materials needed for both wells had to be on location prior to drilling. All well operations were carried out safely without any recordable injuries or accidents. Exploration for older and potentially deeper petroleum systems, particularly in a truly frontierbasin, requires an understanding of the risks for petroleum system generation, timing and preservation. It was recognized that regional geologic extrapolations into the Arafura Sea would basin, requires an understanding of the risks for petroleum system generation, timing and be uncertain until proven by the drill bit. The well results showed that maximum burial and the amount of uplift was greater than originally anticipated. Both wells, the Aru-1 (Amborip VI PSC) and Mutiara Putih-1 (Arafura Sea PSC) were TD’d in the Mid(?) - Late Ordovician section. The entire Silurian, Devonian and Carboniferous were absent. Despite the extreme amount of uplift there still appears to be about 30km of Paleozoic-Proterozoic sedimentary section maximum preserved in this region of the NW Australian continent where the surface is at or close to sea level. This presentation will briefly describe the operational challenges faced in the drilling campaign as well as pre-drill vs. post-drill stratigraphy and the implications of burial history on reservoir quality. It will also present views about the depositional environment that existed to create this anomalous basin thickness.