Abstract

South Coteau field is an example of a stratigraphic play developed in Mission Canyon carbonate islands which developed basinward of an ancient Osagean (Mississippian) shoreline. The Bluell-Sherwood reservoirs are lime packstones to grainstones which lie along a northeast-to southwest-trending structural nose. The trap is a permeability barrier produced by a facies change from higher-energy intertidal facies, to lower-energy lagoonal facies.

Reservoir drive is solution gas expansion. Producing porosities (fenestral, vugular, intergranular, and intrafragmental) range from 2-14%, with permeabilities averaging 5 md. Reserves range from 100,000 to 250,000 bbl of oil per well. The field, when totally developed, will probably exceed 2.5 million bbl total reserves from 12 to 14 wells. Production in the field is presently from three beds: Nesson, Bluell, and Sherwood, all part of the upper Mission Canyon Formation. Additional reserves exist in the Midale beds (Charles Formation).

Well evaluation is accomplished using several parameters. A typical drilling program includes two cores, three or four drillstem tests and a full suite of logs. Even with these data, evaluation is still quite complex.

With drilling depths less than 7000 ft, dry hole costs below $150,000 and reserves averaging 160,000 bbl per well, this field is still economic, even with $10-13 per barrel oil prices.