The Reeves zone is about 500 ft below the top of the Permian San Andres Formation and includes low-energy and high-energy facies in repeated cycles. Lithologic types represented are (1) carbonate mudstone, (2) wackestone, (3) packstone, and (4) oolitic grainstone. Two types of cycles recognized are (1) shelf-edge cycles which culminate in well-developed oolites, and (2) back-shelf cycles which culminate with stromatolitic mudstone.

Three major diagenetic processes that altered the Reeves field carbonate rocks are (1) leaching, (2) dolomitization, and (3) gypsum precipitation--but not necessarily in this order. The grain-supported rocks contained approximately 25% depositional porosity, most of which was infilled by anhydrite; 80% of the perforations are in mudstone-supported facies which, according to core analyses, are permeable and porous. Postdepositional processes have reversed the depositional porosity pattern.

Reeves is a typical Permian basin San Andres field. It was discovered in 1957 and has reserves estimated at 20 million bbl.

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