Case History 8 Extending Field Life in Offshore Gulf of Mexico Using a 3-D Seismic Survey
Thomas P. Bulling, Rebecca S. Olsen, 2011. "Case History 8 Extending Field Life in Offshore Gulf of Mexico Using a 3-D Seismic Survey", Interpretation of Three-Dimensional Seismic Data, Alistair R. Brown
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The High Island 24L field (ARCO), located in the Texas state waters of the Gulf of Mexico, was discovered in 1967. It had produced 320 billion cubic feet (bcf) of gas and 3.0 million bbl of oil by 1986. An engineering field study completed in 1986 projected the field declining to the point of unprofitability within three years. The study found the reservoir maps had three basic problems: volumetric reserve calculations did not equal reserves produced; hydrocarbon-water contacts were inconsistent between wells thought to be in communication; and maps did not define extension opportunities. Attempts to remap the field with the existing 2-D seismic data base and well logs proved unsuccessful.
In 1986, ARCO acquired a 3-D seismic survey and, in 1987, remapped the field starting with the key producing horizons. Integration of detailed well log correlations with the dense grid of 3-D seismic allowed construction of accurate reservoir maps. These new maps helped solve the engineering problems by more accurately defining the configuration of the reservoirs, closely matching volumetrics and fluid contacts as well as defining new extension opportunities. The 3-D seismic survey and its products, along with engineering modifications and operations cost containment, resulted in the extension of the field’s economic life by at least eight years. As more wells are drilled and new information integrated, additional reserves are found.