ABSTRACT: Exploring Ventura Basin, California

Thomas E. Hopps, Howard E. Stark, Robert J. Hindle

Ventura basin in southern California has produced nearly 2 billion bbl of oil and over 3.5 tcf of gas since its first commercial well was completed more than 120 yr ago. The basin is drilled to an average well density of light wells per mi². Nevertheless, over 500 million bbl of untapped reserves may be concealed within its complex geology.

In Ventura basin, complex facies changes and several episodes of intense structural deformation have obscured geologic relationships. Clarification of these relationships can be accomplished through detailed, integrated structural and stratigraphic studies, which encompass a large portion of the basin.

In a recently completed study, maps and a dense network of cross sections pass through nearly every field in Ventura basin. By depicting both structure and stratigraphy, these closely integrated illustrations reveal (1) regional geologic relationships, (2) basin-wide stratigraphic trends, and (3) concealed structures. Locally, they extrapolate known reservoir characteristics and trapping mechanisms from producing fields into adjacent, untested areas.

In complex mature basins, detailed regional studies provide a useful tool for field extension and an essential foundation for prospect generation. The Ventura basin study has identified potential for substantial accumulations of untested hydrocarbons. Similar studies may effectively identify the potential new reserves concealed in other mature basins.

AAPG Search and Discovery Article #91003©1990 AAPG Annual Convention, San Francisco, California, June 3-6, 1990