Significance of Late Pliocene-Early Pleistocene Stratigraphy to Development of Buena Vista Field, San Joaquin Valley, California

Jonathan G. Kuespert

Late Pliocene to early Pleistocene depositional patterns of upper Etchegoin and lower San Joaquin Formation sand and shale units in the Buena Vista field area were controlled by changes in clastic input, eustatic sea level, structural growth, and circulation patterns in the south end of the San Joaquin Valley. Wireline and drill-strip logs, core depositions, paleontology, and petrographic data from these units suggest the interpretation of a series of shallow to marginal marine deposits with distinctive morphologic features and production characteristics. Late Pliocene marginal marine drainage systems transported clastics from southerly sources as structural and/or eustatic changes shoaled the southern area. An erosional hiatus and shallow marine transgression marked the xtent of Plio-Pleistocene shoaling and rapid early Pleistocene foundering. Later Pleistocene changes in sediment supply and structural growth isolated the area from marine conditions as the basin filled with nonmarine sediments. Early field development was influenced by the areal distribution and reservoir characteristics of these sands as well as by the timing of such development activity. Depositional models derived from these data are useful in constructing paleogeographic models with regional hydrocarbon significance.

AAPG Search and Discovery Article #91038©1987 AAPG Annual Convention, Los Angeles, California, June 7-10, 1987.