--> Using Borehole Images To Characterize A Major Fault In The Ventura Avenue Field
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Pacific Section AAPG, SPE and SEPM Joint Technical Conference

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Using Borehole Images To Characterize A Major Previous HitFaultNext Hit In The Ventura Avenue Field


An updated 3D model of the complexly faulted Ventura Avenue Field reveals the geometric relations of the major north and south verging thrust faults that compartmentalize the reservoir. Wells penetrate these thrust faults in a variety of ramp and flat positions. Borehole image logs were obtained for a number of these wells, enabling us to characterize the Previous HitfaultNext Hit zones in the subsurface.

The focus of this study is the Taylor 73 Previous HitFaultNext Hit (named for the well where the Previous HitfaultNext Hit was originally identified). This major south verging thrust acts as an effective seal, separating most of the productive reservoir intervals from shallower zones above. The reservoir facies are turbidite sandstones that include thickly bedded amalgamated units, thinner inter-bedded sandstone and mudstone units, and intervals that are predominantly mudstone. The facies act as contrasting mechanical units that can impact the character of the Previous HitfaultNext Hit zone. The position along the Previous HitfaultNext Hit plane is also a primary factor. Not surprisingly, it is often difficult to identify specific Previous HitfaultNext Hit planes in the flat-on-flat Previous HitfaultNext Hit position. Identifying the Previous HitfaultNext Hit zone in ramp positions is much more obvious, although the character and Previous HitfaultNext Hit expression are highly variable. Previous HitFaultNext Hit cores and damage zones range in thickness from tens to hundreds of feet, and can consist of sheared and fractured intervals, intact rotated blocks, and cemented intervals. Our ongoing work investigates position along the Previous HitfaultNext Hit plane, Previous HitfaultNext Hit separation, and mechanical stratigraphy as factors that impact Previous HitfaultNext Hit expression. Refining Previous HitfaultTop interpretations with image logs constrains the overall subsurface interpretation. We can more confidently distinguish structural from stratigraphic deformation, and identify potentially isolated compartments and barriers in the reservoir.