Maari-1/1A - Results and implications for development

Shell Todd Oil Services (STOS) took over as operator of PEP 38413 in 1997 when Shell Petroleum Mining and Todd Petroleum Mining farmed into the Cultus Petroleum-held licence located 80 km offshore Taranaki. Technical and commercial evaluation by STOS identified several key changes to previous understanding. The most important change was increase in oil volumes for the Moki sands due to re-interpretation of the oil-water contact together with upside realisation in structure due to shallow gas effects on 2D seismic. Well Maari-1 was drilled in December 1998 to assess the Miocene Moki and M2A sands and the Eocene Kapum sands. Following sufficient hydrocarbon and permeability indications, the well was sidetracked as a 654 m horizontal well (Maari-1A) to test for commercial oil production rates. The well flowed 4400 bopd and a significant sampling programme was completed to characterise the reservoir fluids. Major improvements in the understanding of the Maari prospects were: confirmation of the deeper OWC in the Moki sands; confirmation of a laterally continuous reservoir architecture; a production test rate much higher than previous tests; thickening of the M2A sands towards the west; discovery of an 8 m gas column with 33 m oil column in the Kapuni sands; and increased number of options for profitable recovery of waxy oil. Follow up work on Maari showed that economic development of Maari is very likely feasible and attractive. The preliminary field development concept is based around an FPSO with subsea multilateral wells and water injection. However, key uncertainties remain and will be addressed during development planning. A 3D seismic program was completed in 1999 to delineate further upside in the licence and facilitate further development studies. The Maari appraisal program has met with success and was characterised by good multi-discipline teamwork by STOS and Joint Venture partners to assess and resolve major uncertainties in a cost-effective manner.