UNRAVELING STRUCTURAL DEVELOPMENT AND FRACTURE DISTRIBUTION AT DOLLARHIDE FIELD, WEST TEXAS WITH NEW SEISMIC ATTRIBUTE IMAGES

Efficient recovery of reserves from fractured reservoirs depends strongly on understanding the fracture system properties. The fractured Dollarhide Field on the Central Basin Platform, Permian Basin in west Texas is located on a NW-trending anticline, however the structure is in a region with a long and complex tectonic history. Our work reveals the detailed structural evolution of the Dollarhide field, provides important constraints on the regional paleostress history, and shows how fractures developed in the field in response to polyphase deformation.

This work benefits from new 3D seismic attributes developed at the University of Houston. Attributes used to unravel the structure and fracturing include coherence and various derivatives and gradients of the coherent energy, and several types of dip and curvature attributes. Attribute images are enhanced using a new edge-preserving smoothing method. The attributes are viewed as either single-variable or multivariate false-color. These seismic images reveal hard-to-see structural details, normally considered to be subseismic.

The Dollarhide Field is a NW-trending, fault-related anticline bounded on the east by a basement-involved, high-angle reverse fault with up to 2,500 ft of displacement. The anticline initially developed as a fault-related fold during Pennsylvanian NE-directed shortening (D1). Fault-related folding developed differently across NE-striking wrench faults. D1 occurred before and during development of the angular unconformity at the base of the Permian section. The second deformation (D2) was synsedimentary and produced E-W shortening, folding and reactivation of older faults. Seismic-scale fractures indicate a wrench component of D2 folding. The reservoir is compartmentalized by the NE-trending wrench faults and heavily fractured fold forelimbs. This polyphase segmented deformation produced numerous spatial problems and resulted in complex fracturing, compartmentalization, and preferential permeability development within the hydrocarbon reservoirs.