AAPG FOUNDATION PRATT CONFERENCE: PETROLEUM PROVINCES, 21st CENTURY
January 12-15, 2000
San Diego, California

ROBERT M. SNEIDER and JOHN S. SNEIDER, Sneider Exploration Company Inc., Houston, TX

Abstract: New Oil in Old Places

Large reserves are present and recoverable economically in many mature oil fields. Small multidisciplinary teams studied several basins in North America and a few large fields in South America searching for large volumes of low risk reserves in poorly performing fields. The fields studied include those producing by primary recovery with or without secondary recovery potential, and fields undergoing waterflooding. In the United States over 350 mature fields were examined from 1981-1996 looking for fields to purchase. Some large fields were studied for the property owners to rejuvenate the production.

Finding large volumes of low risk, presently non-producing reserves within fields involves several steps. First, the team searches in reservoir systems that appear more massive and homogeneous than they are. Second, the geoscience and engineering data is scanned to estimate original oil-in-place, percent recovery, and bypassed reserves. Third, the team makes an economic analysis including recovery cost estimates. Candidate fields for purchase all have new low to moderate risk reserves amounting to at least 5% of the cumulative reserves already produced.

New reserves are found or exploited by applying one of more of the following: (1) improved drilling/completion technology, (2) identification of by-passed pay, especially very low resistivity pay, (3) new 2D and 3D seismic, and (4) seismic stratigraphic concepts. Additional reserves are found in both land-derived clastic and carbonate reservoirs.

Forty-six mature fields were purchased in the Permian basin of Texas/New Mexico and in the Gulf of Mexico basin. In the fields 625 x 10{6} barrels of oil equivalent of proved and probable reservoirs were added at a cost of US$ 2.70 per BOE. The average after tax rate of return is 21 percent.

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