Integrated Sequence Stratigraphic Based Field Study Processes in a Complex Reservoir System: Applications for Enhanced Depletion and Operating Strategies, Hawkins Field, Wood County, Texas

Victor D. Rahmanian, John M. Clayton, Mark A. Catanzano, Greg S. Benson, Tori B. Barr, Clay L. Collins

This paper summarizes the current results of an integrated geologic-engineering field study undertaken to design and monitor a major EaR project in Hawkins Field (1.5 billion bbl, OOIP). The project goals were to reduce future development drilling requirements, improve success and performance of all future workovers, and Optimize oil recovery through enhanced depletion and operating strategies. The Hawkins Field is a complexly-faulted, salt-supported domal structure producing from the fluvially-dominated Upper Cretaceous Woodbine Formation. The study was conducted through iterative end integrated sequence stratigraphic, structural, and reservoir engineering data analysis utilizing customized computer applications.

The 500-foot thick Woodbine Formation was deposited in an intermittently active syndepositional tectonic setting and subsequently modified by complex post depositional faulting. A major west dipping fault separates the relatively unfaulted east fault block from the more complexly structured central area. The central area contains more than 200 fault blocks bounded by faults with 10 to 400 feet of vertical separation. Five fault domains have been identified which can intersect or overlap creating a complex extensional cross-cutting fault pattern.

The Woodbine is divisible into two retrogradationally-stacked, fluivially-dominated sequence sets of lowstand and transgressive origin. The lower sequence set is dominated by sand-prone, high-frequency sequences marked by multi-story, laterally extensive lowstand braided channel sandstones, overlain by laterally discontinuous interbeds of flood plain mudstones and thin-bedded sandstones of the transgressive systems tract. The sequences of the upper sequence set contain thinner, laterally discontinuous lowstand channels and are dominated by fine grained flood plain deposits of the transgressive systems tract. The Woodbine fluvial sequences are thicker and more sand-prone in flanking synclinal rims and thin as they drape the crest of the structure A noted exception is a half graben in t e central part of the area in which the high-frequency fluvial sequences contain thicker multi-story fluvial channels and related overbank deposits.

Integration of production data with the reservoir framework has resulted in identification of flow unit components, geometries, and pathways. The production data integration is being implemented sequence by sequence on a fault black, and area-wide basis. This has resulted in improved recovery, accelerated oil production, and a reduction of operating costs.

AAPG Search and Discovery Article #91020©1995 AAPG Annual Convention, Houston, Texas, May 5-8, 1995