Historic Oil Field
Clay City Consolidated is the sprawling result of many separate discoveries growing together along the Clay City anticline in southeastern Illinois. Found in 1937 and consolidated over subsequent years across Clay, Wayne and Richland counties with extension toward Jasper County, it is credited with cumulative production above 350 million barrels — roughly 361 million by published accounts. Pay comes from McClosky oolitic limestone, Cypress sandstone and Aux Vases sandstone. The field today is mature waterflood territory: low per-well rates, high water cuts, and mineral title divided among a great many small owners.
The 1937 Clay City discovery was one of the five major finds between 1937 and 1940 that produced the modern Illinois oil industry. What began as separate pools along the Clay City anticline expanded through step-out drilling until the pools merged and were administratively consolidated into a single sprawling field. The anticline trends through Richland and Wayne counties with extension into Jasper, and the traps along it are a mix of structural closures and stratigraphic pinch-outs — a geological variety that gave the field an unusually long development runway.
Drilling ran hot through the late 1930s and 1940s, and the towns along the trend filled with lease brokers, supply houses and drilling crews. Because the field grew by accretion rather than by a single unified development plan, its lease and unit structure is more varied than that of a field developed under one operator. Mineral reservations were made in thousands of separate transactions across four counties, and eighty-odd years of inheritance since has produced the very small undivided fractions typical of southeastern Illinois royalty today.
Secondary recovery followed the same pattern of accretion: individual leases and units were flooded on their own schedules rather than all at once, which is why performance still varies substantially from tract to tract. Operatorship consolidated among Illinois independents as the majors departed. The field now produces at stripper rates with high water cuts, sustained by injection and by the low operating costs that Illinois Basin operators have refined over generations of working mature sandstone and limestone reservoirs.
The field follows the Clay City anticline, a broad structural feature trending through southeastern Illinois that hosts numerous stacked traps. The principal reservoirs are Mississippian: McClosky oolitic limestone, where oolite shoals create porosity in otherwise tight carbonate, plus Cypress and Aux Vases sandstones deposited as channel and bar systems. Because the traps combine structure with stratigraphic pinch-out, reservoir presence and quality change over short distances — one reason lease performance across the field is so uneven and why blanket per-acre valuations are a poor fit here.
Clay City has been developed under waterflood for most of its life, but not uniformly. Because the field assembled from many separate pools, injection was implemented lease by lease and unit by unit over decades, so some tracts sit inside long-established flood patterns while others have seen only limited pressure support. That variation is the single most important thing an owner can know about their acreage. Water cuts are high across the mature basin, and the economics of lifting and disposing of that water set the practical limit on how long any given lease keeps producing.
Because Clay City is really many fields under one name, valuation has to be tract-specific. Two royalty interests a mile apart can differ substantially depending on which zone produces, whether the lease is in a flood unit, and who operates it. We read the lease and unit documents, look at the actual production behind your decimal, and price on method-aware assumptions rather than a blanket multiple. Pointer Minerals buys direct: we buy minerals and royalties in Clay, Wayne, Richland and Jasper counties and provide free written offers.
County-level well data, production charts, and selling guides for the counties this field spans:
It does. The consolidated field covers many originally separate pools with different reservoirs and different flood histories, so the specific lease and unit determine value far more than the field name. Your division order, check detail or the operator’s unit designation will identify it. If you do not have those, we can usually locate the lease from your legal description at no cost.
Some infill and replacement drilling occurs, but southeastern Illinois is a mature stripper province, not an active development play. Most capital goes to workovers, injection maintenance and returning idle wells to service. Owners should not expect shale-scale activity or a step change in production, and we will not price an offer on that assumption.
Yes. One purchase agreement can cover multiple counties, with conveyances recorded in each county where the tracts lie. The main practical requirement is that title be clear in each county separately. We prepare the recording package and walk you through what each county requires before closing.