ABSTRACT: Geologic and Geophysical (G&G) Data Acquisition and Analysis, U.S. Pacific Coast and Gulf of Alaska Marine Tertiary Province

George Dellagiarino

Through fiscal year 1988, the Minerals Management Service (MMS) has acquired 127,200 line-miles of common depth point (CDP) seismic data off of the U.S. Pacific coast and 73,000 line-miles in the Gulf of Alaska Marine Tertiary Province. Data coverage in the Pacific ranges from a ½ × ½ mile grid density in portions of southern California to 7 × 9 miles in portions of Washington and Oregon. For southern Alaska, the grid coverage ranges from ½ × ½ mile in portions of the Gulf of Alaska to single-line coverage throughout the area. More than 1000 wells have been drilled off the Pacific coast, over 900 of which are in southern California. Nineteen wells have been drilled off southern Alaska.

The MMS has subdivided the Pacific region into four planning areas (Southern, Central, and Northern California plus Washington and Oregon) that consist of three geologic provinces. The southern province, which consists of the Santa Barbara Channel and Southern California borderlands, is a primarily mature hydrocarbon-producing area where reservoirs are dominantly sandstones of Cenozoic age. The central province extends from the western Santa Barbara Channel and includes the Santa Maria, Ano Nuevo, La Honda, Bodega, and Point Arena basins. This province is anticipated to have fractured shale reservoirs of the Miocene Monterey and Point Arena Formations. The northern province consists of the Eel River Basin and the small depocenters of Washington and Oregon. Potential reservoirs are pri arily upper Cenozoic sandstones of low reservoir quality.

The Gulf of Alaska Marine Tertiary Province includes the Gulf of Alaska, Kodiak, and Shumagin shelves. G&G data indicate that each of these consists of a main shelf basin with several smaller depocenters. Basement rocks are overlain by mostly shelf and upper slope sediments, The province tends to be gas prone, which is not currently considered commercially viable.

AAPG Search and Discovery Article #90097©1990 Fifth Circum-Pacific Energy and Mineral Resources Conference, Honolulu, Hawaii, July 29-August 3, 1990