ABSTRACT: Geological-Engineering Teamwork: Key to Successful Development of Two Stratigraphic Traps

MEAR, CHARLES E.

Geologist-engineer teams, using only subsurface data, developed and extended two oil and gas fields that produce from stratigraphic traps. The geologists mapped realistic reservoir models, and the engineers used basic reservoir engineering to determine the likelihood of undeveloped reserves being present in the accumulation.

A large stratigraphically-trapped gas deposit present in an unconventional 30-foot thick Hunton dolomite reservoir in Major County, Oklahoma, was developed after a joint geological-engineering study showed that the water level indicated by electrical logs was irreducible water contained in microporosity and illite clay; and that the producing zone extended 300 feet downdip from its upper limit. The zone was artificially fractured to obtain commercial production. The fracture fluid contained as little water as possible to avoid reservoir permeability degradation in the micropores by water and by movement of the illite. Care was taken to avoid fracturing into waterbearing zones.

The Herrin Burson sand (upper) oil field in the Knox-Baylor Trough of Haskell County, Texas, has been redrilled after a joint subsurface study indicated that the field wells had been drilled along the flank of a Strawn sandstone bar, and that most of the wells had communicated with an underlying water-bearing sandstone that caused premature abandonment of most of the field wells. Significant new oil reserves have been developed in extensions and in wells along the crest of the bar.

This paper is an update of a previous paper presented at the Southwest Section (AAPG) meeting in 1992.

AAPG Search and Discovery Article #90947©1997 AAPG Southwest Section Meeting, San Angelo, Texas