Study of Aqueduct field has revealed insights about the seismic signature, reservoir distribution, and possibly oil charging of Stevens fans. These relationships are especially well revealed at Aqueduct because of the field’s structural simplicity and the availability of a diverse data set including high-quality 3-D seismic.

Aqueduct field is a stratigraphic trap formed by pinchout of the upper Monterey Stevens submarine-fan reservoir sand combined with a gentle structural bowing. The sand is time equivalent to updip interfan pelagic siliceous shale that provides the seal.

Aqueduct field lies within the Aqueduct fan system, one of several southernmost San Joaquin basin upper Stevens fan systems deposited within the Monterey. The fan system is expressed on seismic profiles, cross sections, and interval isopach maps as a thick, which is typical for Stevens fans. The distal part of the system is fan shaped, but the proximal part is narrow and linear. Aqueduct field lies in the proximal part of the fan, where the lateral pinchouts of sand from the fan axis to flanking shale are abrupt. In spite of the linear proximal fan shape, we interpret that erosion at the base of the fan was minor. In the distal fan, sand passes gradationally from the fan axis to siliceous shale in the interfan area.

Seismic, geochemical, and oil-water contact data suggest that Aqueduct field probably is compartmentalized into at least three separate oil pools. Sands at Aqueduct field may have been deposited as a series of prograding shingled fan lobes. If so, we interpret that the shales between these shingled lobes isolated the pools from one another.

Aqueduct field has smaller reserves than nearby fields that are otherwise similar and is remarkably unfaulted. The small size may be due to charge limitation. At Aqueduct field, the absence of faults to facilitate vertical oil migration from the lower Monterey hydrocarbon kitchen upward into the reservoir may limit field size.