The Mayfield gas pool, most prolific Newburg "sand" pool in Ohio, is in northeastern Cuyahoga County. The rocks that have been tested by drilling range from Upper Ordovician to Upper Devonian. Outcrops include rocks of Upper Devonian and Mississippian age. They are extensively covered by Pleistocene and Recent deposits. Gas and a small amount of oil is obtained from the Newburg "sand" (Middle Silurian) at an average depth of 2,875 feet, and from the Oriskany sand (Lower Devonian) at a depth of about 1,800 feet. The reservoir is of the structural type in the Oriskany sand and of a combined structural and porosity type in the Newburg "sand." The structure is incompletely outlined because of Pleistocene cover at the surface and restrictions on drilling south and southwest of the pool. At the surface it is dome-like with limbs dipping about 0°-18^prime. In the subsurface it appears to be a broad anticline trending northeast with a known closure of approximately 100 feet. Its southeast limb dips about 0°-38^prime. Fifty-two tests, eleven of which were dry holes, have been drilled on the anticline. The total yield of gas, as of December 31, 1947, has been about 13½ billion cubic feet from wells showing a distribution ratio of 30 acres per well. The chances of obtaining oil or gas from deeper Ordovician and sub-Ordovician strata are considered to be chiefly dependent on the amount of closure that occurs in the structure in these deeper strata, and on the porosity of the rocks.

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