An integrated subsurface engineering study was undertaken to examine ways to optimize high cost, technically difficult Pliocene/Pleistocene turbidite developments in the Gulf of Mexico.This study utilized a multidisciplinary approach in which both open and cased hole data was applied to quantifying and qualifying downhole flow performance in different turbidite facies.Data from Produce While Drilling (PWD) operations and Pressure Volume Temperature (PVT) tests proved to be extremely valuable when combined with base wireline logs in delineating the production characteristics through time.

This paper outlines our results and experiences in hydrocarbon typing Pliocene/Pleistocene turbidite sand reservoirs in two Shell Offshore Inc. Gulf of Mexico fields. While differentiation of hydrocarbon type was important in identifying completion targets for Produce While Drilling (PWD) operations, hydrocarbon typing was extremely difficult. This hydrocarbon typing problem was a result of (1) compositional make-up of both oil and gas, (2) high reservoir pressures encountered (up to 10,000 psi), (3) geological complexity (structural and stratigraphic), (4) the use of oil based mud to drill many wells, and (5) complex mineralogical makeup of the sands.Because openhole data and routine pulsed neutron capture (PNC) data were often inconclusive, secondary curves presented on PNC logs were extensively examined. The PNC ratio of inelastic short to long spaced data (RIN) was found to be an extremely diagnostic gas indicator, and has been used to further refine and calibrate petrophysical evaluations. These refined evaluations were then incorporated into redesigning a new completion strategy for each well examined. ScheibalWeiland Worrell Bayer