Print this pageAAPG GEO 2010 Middle East
Geoscience Conference & Exhibition
Innovative Geoscience Solutions – Meeting Hydrocarbon Demand in Changing Times
March 7-10, 2010 – Manama, Bahrain
Exploration Campaign Drilling for Low-Relief Channel-Sand Prospects, South Central Oman
(1) Exploration, PDO, Muscat, Oman.
During 2009/10, PDO Exploration is executing a ‘peephole’ exploration/appraisal campaign for 2 prospects in the vicinity of a field which was developed using several grid drilling campaigns since 1990. The Field, discovered in 1986, is a low relief anticline (approximately 45m relief and 100 km2 closure) located in central Oman. The oil is produced from the Permian Upper Gharif channel sands, deposited within a predominantly muddy floodplain and hence with a relatively low net/gross of some 30%. The oil is 24o API with a viscosity of 45cP. Experience, gained during the appraisal and early development stages of the field, is being brought to bear on the exploration and appraisal of its satellites. The initial field development was based on the drilling of high-angle, deviated wells aimed at maximising the chance of finding the fluvial channels. This achieved a low rate of success at a high drilling cost. A new strategy of drilling multiple, low-cost, vertical wells (peepholes) was implemented. The economics of this campaign drilling could tolerate the expected low success rate, eventually improving understanding of the reservoir distribution patterns and reducing uncertainty in targeting productive sands. The first peephole campaign in the field started in 2001. Twenty wells were drilled with a success rate of 60%. The ensuing second campaign drilled another 12 wells with a success rate of 66 %. Both campaigns resulted in a substantial production increase and met both the economic and geological success criteria. Using this field development as an analogue, 12 wells have been incorporated on the Exploration drilling sequence to appraise the first satellite prospect. A further 10 wells are planned on a second prospect in 2010. This paper will share the results and learnings of the first drilling campaign. The first campaign well proved an oil bearing zone with a much higher net/gross than the historical exploration well.