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Title: Characterization of gas fields by petroleum system, Sacramento Basin, California

Conference · · AAPG Bulletin
OSTI ID:6581939
;  [1];  [2]
  1. Geological Survey, Menlo Park, CA (United States)
  2. California Division of Oil, Gas and Geothermal Resources, Sacramento, CA (United States)

The Sacramento Basin, a north-trending forearc basin, contains Late Jurassic to Holocene sedimentary rocks that thicken to the south. The basin fill is about 300 km long, 80 km wide, and as much as 16 km thick. Because the 157 gas fields with original reserves of 9.14 tcf (1012 ft3) cover a large area, a change in chemical composition due to migration from wet gas to pure methane is recorded. On the basis of the carbon-isotopic composition of methane and stratigraphic occurrence, two petroleum systems have been identified in the Sacramento Basin. The Dobbins-Forbes( ) gas system, which contained about 2.25 tcf of recoverable gas, underlies the Winters-Domengine( ) gas system, which contained about 6.89 tcf of recoverable gas. Gas migrated laterally to the north as far as 200 km in the Dobbins-Forbes( ) system, whereas in the Winters-Domengine( ) system, gas first migrated vertically and then crossed the Midland Fault to the east for as far as 40 km. In both systems, depth of gas production is less than 3 km. By applying the petroleum-system concept and available information about the geology and geochemistry of this province, our study provides a new testable hypothesis for the origin, migration, and accumulation of gas in the Sacramento Basin. By reinterpreting some of the natural-gas information, along with data on gas wetness, gas-oil ratio, vectors of migration, hydrocarbon volume, and thermal history, two gas systems have been identified.

OSTI ID:
6581939
Report Number(s):
CONF-960527-; CODEN: AABUD2
Journal Information:
AAPG Bulletin, Vol. 5; Conference: Annual convention of the American Association of Petroleum Geologists, Inc. and the Society for Sedimentary Geology: global exploration and geotechnology, San Diego, CA (United States), 19-22 May 1996; ISSN 0149-1423
Country of Publication:
United States
Language:
English