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ABSTRACT: Extending Field Life in Offshore Gulf of Mexico Using 3-D Seismic Survey

Thomas P. Bulling, Rebecca S. Olsen

Discovered by ARCO in 1967, the High Island 24L field (lower Miocene) is located in the Texas state waters of the Gulf of Mexico. By 1986, the field had produced 320 billion ft3 of gas and 3.0 million bbl of oil. An engineering field study completed in 1986 showed the field was declining and would be unprofitable within 3 yr. Study of reservoir maps revealed three basin problems: volumetric reserve calculations were less than reserves produced, hydrocarbon-water contacts were inconsistent between wells thought to be in communication, and ultimate recoveries could not be accurately calculated. Attempts to remap the field with the existing two-dimensional seismic data base and well data proved unsuccessful. In 1986, a three-dimensional seismic survey was acquired in an effort to evaluate the true present worth and potential of the field.

Remapping of 30 reservoir horizons began in 1987. The integration of detailed well log correlations tied to the dense grid of quality three-dimensional seismic data improved the reservoir maps. These maps helped resolve engineering problems by defining the configuration of the reservoirs more accurately. Reservoir maps now closely match volumetrics, fluid contacts within reservoir units are consistent, and a better definition of extension well opportunities exists. Our study resulted in six additional wells. These wells along with engineering modifications and operations cost containment resulted in the extension of the economic life of the High Island 24L field by at least 8 yr.

AAPG Search and Discovery Article #91003©1990 AAPG Annual Convention, San Francisco, California, June 3-6, 1990