ABSTRACT

Livingston Field's main Eocene producing interval, the 1^st Wilcox sand reservoir, was discovered in 1983 at a depth of approximately 10,000 feet (3048 meters). After completion of twenty-two successful producers and a secondary waterflood in the reservoir, the cumulative production is approximately 8.8 million barrels of oil and 4.7 billion cubic feet of gas. In the past, several field studies have been made of the main producing interval. However, only two of these included reservoir simulation. From these studies, the original oil in place was estimated to be between 24.5 and 32.6 million barrels. Therefore, present recovery efficiencies of 39 to 30 percent, from both the initial primary gas solution drive and secondary waterflood phases of production appear to be low for a reservoir containing 35° API gravity oil, core permeability averages of 290 millidarcys, and an average porosity of 20.4 percent.

A 2001 geological and engineering field study, incorporating advanced reservoir simulation technology, provides a new definitive high-resolution multi-layered model. This facilitates more accurate spatial mapping of the petrologic heterogeneities that occur within the producing reservoir. Therefore, a more reliable basis is established for (1) locating the suspected non-swept remaining reserves within the reservoir and (2) explaining the heretofore-low recovery efficiency of less than 39 percent. Armed with a new identification of the reservoir's specific petrological spatial relationships and a multi-layered simulation-based tertiary production plan, we expect significant further reserve recovery for the field.