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The AAPG/Datapages Combined Publications Database

AAPG Bulletin


Volume: 63 (1979)

Issue: 3. (March)

First Page: 488

Last Page: 488

Title: Porosity in Giant Gas Field, Ellenburger Formation, Puckett Field, Pecos County, Texas: ABSTRACT

Author(s): R. G. Loucks, P. A. Mench

Article Type: Meeting abstract


The Lower Ordovician Puckett field has produced nearly 2.5 Tcf of gas from the Ellenburger Dolomite since the discovery of the field in 1952 by Phillips Petroleum Co. Production is from a depth interval of approximately 12,000 to 15,000 ft (3,600 to 4,500 m), and the estimated ultimate recovery is 3.3 Tcf.

The Ellenburger facies are interpreted to have been deposited in several major environmental settings--subtidal, intertidal-channel belt, and supratidal. Subtidal deposition is represented by burrowed, irregularly laminated mudstones and wackestones and by oolitic grainstones. In the intertidal-channel belt, intraclastic packstones and stromatolitic boundstones accumulated. Laminated mudstones and algal-laminated mudstones were deposited on the supratidal flats in which desiccation produced mud cracks and thin layers of flat-pebble conglomerates. During Ellenburger sedimentation there were many periods of subaerial exposure which resulted in formation of soil zones and karst terranes as deep as 20 ft (6 m). Solution collapse produced thick brecciated zones.

Maximum porosity in the reservoir is 12% and the greatest permeability is 117 md. Porosity originated dominantly from tectonic and karst fractures and karst vugs. The generally low porosity is locally enhanced by intercrystalline, moldic, and interparticle porosity. The greatest porosity and permeability is commonly in the facies of the supratidal and intertidal environments most affected by tectonic fractures and by soil and karst development.

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