This study provides a seismic-scale sequence stratigraphic framework for the 1300 meter upper Neogene succession of the Bakersfield Arch, southern San Joaquin basin, California. An evaluation is made, within the context of time-significant stratigraphic surfaces, of the shallow-marine siliciclastic strata of the late Neogene Etchegoin (upper Miocene to Pliocene) and the San Joaquin (Pliocene) Formations which have produced 10.4 billion m³ (367 billion ft³) of dry gas within and adjacent to the study the area.

Three-dimensional seismic data allow seismic-scale (50-150 m) interpretation of eight unconformity-bounded stratigraphic sequences. Well log data enable interpretation of reservoir-scale (meter) parasequences and parasequence sets within each sequence. These sequences, labeled ‘A’ through ‘H’ in ascending stratigraphic order, prograded and thickened west-southwest to fill the basin. Each sequence contains northeastward-onlapping transgressive systems tracts, separated by a flooding surface from the overlying southwestward-downlapping highstand systems tracts. A third systems tract, the lowstand wedge, is represented by incised valleys (widths of 180-600 m) on the uppermost highstand deposits of sequences ‘B’, ‘C’, ‘E’, and ‘F’ Each transgressive and highstand systems tract contains 30- to 80-m thick parasequence sets with characteristic stacking patterns composed of 6- to 20-m thick parasequences.

Rapid subsidence plus high sediment flux in the Bakersfield Arch area resulted in the preservation of systems tracts and the compartmentalization of basinward lowstand wedges in the Arch. Detailed mapping at the North Coles Levee field of 6- to 18-m thick lower Gusher gas sands in the lowstand wedge of sequence ‘E’ reveals a wave-modified, tidal environment with a retrogradational stacking pattern, indicative of deposition at or near the onset of a relative rise of sea level.

Pliocene deformation of the basin combined with a eustatic sea level fall resulted in a distinct change in depositional style from coarsening-up and fining-up parasequences capped by shales to a continuous series of coarse-based, thinning and fining-up sandstones, seen at both the seismic- and reservoir-scales of observation during deposition of sequence ‘H’. Following this change, shallow-marine facies were displaced upsection by non-marine facies of the Pleistocene Tulare Formation.

This study of the integrated effect of tectonics, relative sea level, and sediment flux, in the context of a sequence stratigraphic framework, will enable better prediction of the geometries and facies distributions of gas-prone Neogene sands in the San Joaquin basin.