Sequence stratigraphy of a Pliocene delta complex deposited in an active margin setting, Etchegoin and San Joaquin gas sands, San Joaquin basin, California

Conference · Mon Jan 01 04:00:00 EST 1996 · AAPG Bulletin

OSTI ID:6567926

Steward, D C ^[1]

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1. California State Univ., Bakersfield, CA (United States)

Prolific gas sands of the Pliocene Etchegoin and San Joaquin formations of the southern San Joaquin basin, California, are part of a 1300-m thick succession of deltaic sediments that record the final regression of the Pacific Ocean from a tectonically active, restricted basin associated with the California transform margin. Individual field studies, lacking a regional framework and based primarily on electric log data, correlate these gas sands to the extent that individual sands maintain the same stratigraphic level within the succession. However, a high-resolution sequence stratigraphic framework, constructed from recent 3D-seismic data and detailed well log correlations on the Bakersfield Arch area of the basin, indicates that the Pliocene succession is part of a south/southwest prograding delta complex. Therefore, sands climb up-section in the landward direction and grade laterally from deep-water to shallow-water facies. Because lithofacies boundaries cross chronostratigraphic surfaces, previous interpretations of the reservoir architecture are inaccurate. This model increases predictability of reservoir facies by constraining lithofacies mapping and enables interpretation of the effects on deposition of the integrated and inter-related controls of tectonics, eustatic sea-level change, and sediment supply. With this understanding, a well-defined model of the stratal architecture of the Pliocene succession of the southern San Joaquin basin is now possible.

• OSTI ID: 6567926
• Report Number(s): CONF-960527--
• Conference Information: Journal Name: AAPG Bulletin Journal Volume: 5
• Country of Publication: United States
• Language: English

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030200* -- Natural Gas-- Reserves
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