Discovered in 1937 and now one of the nation's larger waterflood developments, the Loudon pool, Ill., has a history of practical application of advanced conservation techniques. Careful spacing analysis, multiple horizon completions and gas partial pressure maintenance were all part of primary depletion history. Primary recovery of 180,000,000 bbl from 24,500 productive acres of Chester sands will be greatly enhanced by the current waterflood operation. Waterflood exploitation was begun in 1950. After flood ability was demonstrated, an expansion program was begun and by June 1, 1957, the flood covered an area of 13,700 acres. Current planning indicates the flood area will total 19,000 acres when fully developed. Water flooding has increased total pool production 21,000 B/D during the past four-year period. Because of the flood program size, unique problems have been encountered in maintaining an adequate supply of water for injection. Waterflood behavior of the reservoirs has been carefully analyzed as a guide to optimum ultimate results.
The Loudon pool is located in south-central Illinois on the northwest flank of the Illinois basin. Its location in relation to other producing pools in the basin is shown in Fig. 1. Since discovery of the field in 1937, development and production operations at Loudon have been characterized by use of the best conservation practices which were applicable. The latest and most significant of these techniques is the water flood program which by June 1, 1957, covered 13,700 acres, involving the properties of 40 operators. The water flood is expected to increase pool ultimate recovery by 140,000,000 bbl.
The producing horizons under flood at Loudon are four Mississippian Chester sand reservoirs, the Weiler, Paint Creek, Bethel and Aux Vases, encountered at subsurface depths ranging from 1,400 to 1,600 ft. Productive areas of these four reservoirs are outlined in Fig. 2. The Weiler, Paint Creek, and Bethel sands contribute the principal oil reserves.
