Analysis of Fracturing and Fluid-Flow Characteristics of the Monterey Formation, Santa Barbara Channel, CA

Abstract

ABSTRACT Analysis of fracturing in the Monterey formation in core and outcrop demonstrates the interrelations among the regional stress field, the fracture pattern geometry and connectivity, and the hydrocarbon migration and production characteristics of the Monterey. The spatially and temporally persistent fracturing consists of four predominant subvertical sets striking approximately N30E, N55E, N67W and N15-30W. The northeasterly sets possess the greatest areal density and are often the primary set against which others terminate. They are also the most frequently filled with tar and calcite, particularly where they are near oblique-slip faults. A regional northeasterly maximum compressive stress field that has persisted from Pliocene time to the present selectively enhanced subvertical northeasterly-striking fractures. This stress field made the northeasterly joints the favored fractures for the migration of fluids through the fracture network. Statistical analysis of the joint network indicates a northeasterly direction for the maximum fracture network permeability, consistent with offshore production data. Computer-generated synthetic fracture networks constructed from the field data illustrate the impact that faults, major joints and slump or breccia zones may have on integrating poorly connected fracture network clusters, thereby enhancing directional flows.