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Geology and Development of Pitas Point Gas Field

Michael P. Nelson, Steven L. Hart, Greg J. Cavette, Wayne P. Ziemianski

The Pitas Point field produces gas from the Pliocene Pico and "Repetto" formations along an east-west-trending anticline located on OCS leases P-0233, P-0234, and P-0346, 9 mi south of Carpinteria in the Santa Barbara Channel, California. The field has produced 84 bcf (through July 1987), at an average daily rate of 60 MMCFGD, from low-resistivity turbidite sandstones. The Pitas Point structure is an asymmetric (steeper north flank), broad, unfaulted anticline. The maximum area of gas accumulation is 1,900 ac.

In the field area, 15,000 ft of Pliocene-Pleistocene sandstones and shales are present. The major gas pay zones occur between 9,900 and 12,000 ft subsea. Shallow pay zones are also present from 3,500 to 7,500 ft subsea. The deep zone reservoir sandstones are thinly bedded, deep-marine, distal submarine-fan deposits. Bed thickness, grain size, and the sandstone-to-shale ratio all increase upsection, suggesting southwestward progradation of a submarine fan across the field area through time. Pay sandstone resistivities are typically less than 3 ohms and can be less than 2 ohms. Resistivities are suppressed because of (1) high water saturations, (2) conductive pore-lining clays (smectite), and (3) bed thicknesses that are less than logging-tool resolution. Between 1983 and 1986, 17 direc ional wells were drilled from Platform Habitat (20 slots). In the deep pay zones, seven wells were dually completed and three are single completions. Average initial production for individual completion zones was 4 MMCFGD. Four wells are completed in the shallower gas zones.

AAPG Search and Discovery Article #91035©1988 AAPG-SEPM-SEG Pacific Sections and SPWLA Annual Convention, Santa Barbara, California, 17-19 April 1988.