The Hyden West pool of northeastern Leslie County in eastern Kentucky produces from the Mississippian "Big Lime" (Greenbrier or Newman Limestone). The pool includes approximately 7,000 acres (2,800 ha.), with more than 60 wells which range in depth from 1,900 to 2,400 ft (570 to 720 m). Production in the pool is primarily gas, with small amounts of oil, from the basal Greenbrier.

Drill cuttings from 10 wells within the pool and on its margins were studied using a binocular microscope. The thickness of the Greenbrier was determined throughout the pool from gamma-ray logs and samples. Drillers' logs have been used cautiously, and only if other sources of data were unavailable. These thicknesses, as well as intervals within the Greenbrier and structural data from the logs, were used to construct maps and cross sections of the pool.

The Greenbrier has a thickness of between 160 and 250 ft (48 and 75 m) in this pool, and consists of limestone and dolomite, with minor amounts of shale. Evidence suggests that the sequence was deposited in a shallow epicontinental sea that was transgressing across low-lying, exposed surfaces of the Maccrady siltstone.

The dolomite present in the basal part of the Greenbrier is mainly a secondary replacement of limestone. Porosity and permeability in the dolomite provide the pay zone of the Hyden West pool.

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