Columbia Gas Transmission Corp., one of the natural gas suppliers to Washington Gas Light Co. in the metropolitan area, has found "what it believes to be a major" discovery of natural gas in West Virginia.

In an announcement today, Columbia Transmission Chairman W. W. Ferrell said preliminary evaluation of two new wells drilled south of Keyser, W. Va., indicates natural gas reserves in the Mineral County area of the state's Eastern Panhandle region are significant.

"But more importantly, we now have tangible evidence that commercial reserves of natural gas exist," Ferrell said, in a region called the "Eastern Overthrust Belt" - a vast geologic area extending 650 miles from Alabama through portions of Tennessee, Kentucky, West Virginia and Virginia into Pennsylvania.

Columbia Transmission, a unit of Columbia Gas System, drilled two wells to a depth of 8,500 feet into sandstone at a cost of more than $2.5 million, the company stated.

Gas production in the overall "belt" has been limited because of high costs and the sharp rock formations of the region, Ferrell added. But the West Virginia discovery covers only a tiny portion of the Alabama-Pennsylvania region involved. The Columbia Transmission officer forecast that success in Mineral County, along with price incentives under new federal law, will accelerate drilling for natural gas in the region.

While development costs would be comparable to other U.S. sources, the proximity of West Virginia fields to Columbia's markets in the East and Midwest make it attractive economically because transport costs would be reduced, Ferrell added.

Columbia Transmission serves 75 retail gas companies in seven states and D.C. About 10 percent of Columbia's total gas supply in 1978 came from Appalachia. Columbia spent $20 million on exploration and development of gas fields in the region last year and plans a similar outlays in 1979.

Washington Gas also has drilled on its own for natural gas in West Virginia. CAPTION: Graph, The Market, July 16, The Washington Post