ABSTRACT

Maps of field well estimated ultimate recoveries (EUR), a qualitative indicator of reservoir porosity and permeability, can represent paleostructure if hydrocarbon emplacement of the field occurred pene-contemporaneously with deposition. In structurally complex fields, this type of qualitative understanding from quantitative data can supplement the geoscientist's knowledge of the field. West Cameron Block 205 field provides an example.

West Cameron Block 205 field produces from the Middle Miocene Cristellaria (I) and Cibicides opima sandstones deposited in outer neritic environments and is projected to produce 310 BCFG. Structure maps indicate that the field is a complexly faulted south-plunging anticline. Unfortunately, the trapping mechanism is poorly understood: closure, with 1500 feet of column, is placed anomalously against minor faults; the gas/water contacts and gas columns vary within reservoirs; the structurally highest well is dry; and most of the flank wells are the best producers.

EUR maps indicate that the field was a four-way closed anticline during hydrocarbon emplacement. EUR values can be calculated easily from readily available production data, and are not subject to anthropogenic factors that appear in maps of initial absolute open-flow rates or of yearly production. The geoscientist can exploit estimated ultimate recovery maps to understand not only field production, but also paleostructure in structurally complex areas.