ABSTRACT

Uncertainty exists concerning the range of production performances to expect from different deep water reservoir facies. South Timbalier 295 is one of a select few Gulf of Mexico fields with production history data available from several different turbidite depositional settings.

Since its discovery in 1984, 27 wells have been drilled at South Timbalier 295 Field. Reserves are 25 million barrels of oil and 125 billion cubic feet of gas. A very successful six-well drilling program was recently conducted and was based on a fully integrated (3-D seismic, well and production data) field study completed in 1991. Cross sections and detailed field maps were constructed for every pay sand. Additionally, a series of subregional interval and net sand isopachs were built and then used to reconstruct the tectonic history of the area, which helped define how paleostructure influenced deposition.

The "K8," interpreted as a series of mid-fan turbidite sheet sands which lapped onto a paleohigh, is characterized by good lateral continuity. Over 1,000,000 barrels of oil have been produced from Well A-12 at a sustained daily rate of 1,500 barrels with only a small pressure change. Hydrodynamic pressure is likely.

The "K16" consists of amalgamated channel sands characterized by rapid lateral variation. Interval and net sand isopachs also indicate thinning onto a paleohigh. Despite the channelized architecture of the "K16," connectivity of channels across amalgamation surfaces appears to be common. High sustained production rates with little pressure change indicate connection to a large aquifer.

The "K40" consists of two separate turbidite ponded basin sheet sands which were deposited in a ponded basin, onto a paleohigh, and pinch-out updip. Over 800,000 barrels of oil have been produced from the A-5 well at a sustained rate of 1,200 barrels daily. Good recoveries, little pressure change, and noticeable movement of the oil/water contact suggest good lateral continuity and support by a large downdip aquifer.

All three reservoirs are fine grained, moderately well sorted, subarkosic sandstones. Porosity and permeability are approximately 31% and 500 MD, respectively, for all three reservoirs.