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The AAPG/Datapages Combined Publications Database

AAPG Bulletin


Volume: 55 (1971)

Issue: 9. (September)

First Page: 1694

Last Page: 1694

Title: "G2" Channel Sandstone, Main Pass Block 35 Field: ABSTRACT

Author(s): James A. Hartman

Article Type: Meeting abstract


The Main Pass Block 35 field is in the Gulf of Mexico about 50 mi southeast of New Orleans in 10 ft of water. The general structure of the field is that of a rollover anticline on the downthrown block of a south-dipping contemporaneous fault which at the "G2" level has about 200 ft of displacement. The Miocene "G2" sandstone, the largest single reservoir in the field, is a classic example of oil production from a stream channel. The channel has a maximum width of about ½ mi, and its edges are closely defined by dense well control. The gas-oil contact is at 6,636 ft subsea and the oil-water contact at 6,690 ft subsea. Nineteen wells or sidetracks have been completed in this sandstone, and ultimate recovery will exceed 12 million bbl of oil.

The "G2" channel sandstone is a clean, well-sorted, fine-grained quartz sandstone with up to 20% feldspars and minor amounts of clay and carbonate. Average porosity is about 34%, and average permeability is in excess of 3 darcys. Bottomhole pressure data indicate that continuity within the channel is excellent. In contrast to the channel sandstone, the associated natural levee and backslope deposits are very fine-grained sandstone or siltstone. Average porosity is about 26%, and average permeability is about 75 md. The "G2" sandstone series is part of a delta system which was advancing from the northeast toward the southwest. Following deposition of the "G2" channel sand, the delta abandoned this channel and the entire area subsided. The overlying shal s are of marine deposition.

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