Multidisciplinary study to optimize reservoir management of the North Penwell (San Andres) unit, Ector County Texas

Journal Article · Fri Sep 01 04:00:00 EDT 1995 · AAPG Bulletin

OSTI ID:159948

Siemers, W T; Howard, J J ^[1]; Gerard, M G ^[2]

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1. Phillips Petroleum Company, Bartlesville, OK (United States)
2. Phillips Petroleum Company, Odessa, TX (United States); and others

A reservoir characterization study of the North Penwell (San Andres) Unit was undertaken to optimize a waterflood expansion project. The Permian San Andres Formation in Penwell Field is composed of dolostones deposited as repeated, shallowing-upward, peritidal, carbonate sequences on the eastern shelf of the Central Basin Platform, forming a reservoir with complex internal geometry. Late-diagenetic dissolution of anhydrite and dolomite, marked by the complex internal geometry. Late-diagenetic dissolution of anhydrite and dolomite, marked by the alteration of anhydrite to gypsum within the subtidal, peloidal/skeletal, grain-rich lithofacies, is the major contributor to good porosity development and determines the occurrence of improved reservoir quality. Ranges in reservoir quality are linked to variable aspect (pore/throat) ratios derived from a unique combination of diagenetically evolved polymodal pore-size distributions and unimodal throat-size distributions. The best quality reservoir rocks are dolomitized packstones and grainstones with a well-developed, solution-enhanced interparticle/grain-moldic pore system of intermediate pore size. The subtidal grain-rich intervals serve as major flow units within the reservoir because of their good lateral continuity and internally consistent flow characteristics. A model based on an open-restricted-closed diagenetic system is proposed in which high-quality reservoir flow units grade into layers of anhydrite-cemented dolostones representing the hydrologically less active boundaries of the flow units. The flow units defined by the distribution of porosity and permeability identified from the petrologic study were utilized to construct a preliminary 3-dimensional geocellular model. A reservoir simulation pattern model was used to test the geological model by matching simulation results with field performance.

• OSTI ID: 159948
• Report Number(s): CONF-951094--
• Journal Information: AAPG Bulletin, Journal Name: AAPG Bulletin Journal Issue: 9 Vol. 79; ISSN 0149-1423; ISSN AABUD2
• Country of Publication: United States
• Language: English

Related Subjects

02 PETROLEUM
ENHANCED RECOVERY
OIL FIELDS
PETROGRAPHY
PETROLEUM
PETROLEUM DEPOSITS
RESERVOIR ROCK
RESOURCE DEVELOPMENT
STRATIGRAPHY
TEXAS
WATERFLOODING