The Illinois Basin has produced oil for a century with no severance tax, no public well-level production data, and a court process that can hand an unknown owner's minerals to the surface owner. Most of what is under southern Illinois is owned by families who inherited it and have never seen a number for it.
Illinois is a quiet state with a loud history. The basin has produced more than four billion barrels since the 1880s, almost all of it from shallow vertical wells in a few dozen counties across the southern third of the state, and nearly all of it today from stripper wells that pay small, steady, decades-long royalties to families who have never been asked what they would take for them.
Berlin buys Illinois minerals and royalties, producing and non-producing, in every county of the basin, and we buy the interests other buyers skip: the eighty-dollar checks, the fractions split across nine cousins, the tract in White County that your grandmother leased in 1952.
Illinois produced 6.8 million barrels in 2025 from 43 counties, the lowest total since 1936, which tells you two things at once: the basin is old, and the wells keep producing anyway. White County alone produced 2.1 million barrels, nearly a third of the state. Marion, Crawford, Wabash, Fayette, Franklin, Clay, Wayne, Lawrence, and Hamilton round out the top ten, and the top fifteen counties account for about 90 percent of the oil.
Six consolidated fields produce roughly half the basin: Clay City, Lawrence, Louden, Main, New Harmony, and Salem. Louden and Salem are the two largest. The pay is Mississippian more often than not: Chesterian sands like the Cypress account for about 60 percent of the basin's oil, the Ste. Genevieve, Salem, and Aux Vases for more than a fifth, Pennsylvanian sands along the La Salle anticline for about 13 percent, and the Devonian and Silurian for the rest. The New Albany Shale is the source rock, and while the 2013 High Volume Horizontal Hydraulic Fracturing Act set up a permit program for it, the basin has stayed a vertical, waterflood, conventional province.
Campbell Energy of Carmi is the largest producer in the basin, and consolidation has been steady, including Campbell's purchase of Rex Energy's roughly 76,000 net acres. CountryMark buys crude from independents across the basin and posts its price daily, which is the number most Illinois royalty checks are built on.
No severance tax on conventional production. Illinois is one of the few producing states with no severance or gross production tax; the Hydraulic Fracturing Tax Act reaches only wells permitted under the horizontal fracturing law, at 3 percent for 24 months, and almost none exist.
A payment statute with teeth. The Oil and Gas Rights Act, 765 ILCS 520/10, requires first payment within 150 days after the end of the month of first purchase, then payment per the lease or within 60 days for oil and 90 days for gas after the month of sale, with interest at the New York Fed discount rate on late amounts. Thirty days written notice is required before suit. Our letter generator writes it.
Unclaimed money goes to the Treasurer after three years. Illinois' unclaimed property act, 765 ILCS 1026, defines mineral proceeds to include royalties, bonuses, delay rentals, and overriding and net revenue interests, with a three year dormancy. If a family's checks stopped a decade ago, the money is likely sitting with the State Treasurer under the decedent's name. We search it free; see unclaimed royalties.
No self-executing dormant mineral act, but a court process that ends the same way. The Severed Mineral Interest Act, 765 ILCS 515, lets a surface owner petition the circuit court against severed minerals whose owners are unknown or missing, with published and mailed notice. The court can appoint a trustee to lease the interest, and can eventually vest it in the surface owner: seven years after the judgment, or one year where the severance was more than 20 years old at filing. An owner can intervene before final judgment. The defense is simple and almost nobody does it: keep a recorded instrument with a current address in the county.
Severed minerals are real estate in Illinois. The small estate affidavit, 755 ILCS 5/25-1, reaches personal property only, up to $150,000 since August 2025, and cannot be used if the decedent owned any Illinois real estate. That means an Illinois probate, or for an out-of-state decedent an ancillary probate in the county where the minerals sit, before clean title can pass. A transfer on death instrument under 755 ILCS 27 avoids all of it for the next generation if recorded before death. Illinois does have an estate tax, with a $4 million exemption, which rarely touches a mineral estate on its own but matters for larger ones.
On a committed purchase, we coordinate and pay for the probate or ancillary proceeding. Our executor's checklist lays out the ten steps in order.
Illinois publishes no well-level production. The Illinois Petroleum Resources Board compiles annual county totals from first-purchaser reports, and the State Geological Survey's ILOIL map carries well records, logs, and field outlines, but the monthly volumes that drive a valuation are not public. That makes your division orders, check stubs, and 1099s the primary record, and it is why a buyer's formula letter built from purchased data is even less reliable here than elsewhere. We value Illinois interests off your actual statements, the field's history, and the operator's posted price, and we show the work.
Text a photo of a check stub to 918-984-1645 and you will have a written number within two business days.
Illinois is where carbon storage is actually happening: thirteen Class VI projects proposed, the EPA's April 2026 final permit for Marquis in Putnam County, ADM's Decatur wells back injecting after a 2024 leak and a 2025 federal order, and a 2025 law banning sequestration over the Mahomet Aquifer. The 2024 SAFE CCS Act settled the ownership question in the surface owner's favor: pore space belongs to the surface estate, operators need agreements from at least 75 percent of affected owners before petitioning to unitize, and the CO2 stays the operator's property. If you own minerals under a proposed storage footprint, expect to be mapped and contacted. Our pore space and carbon storage page explains what the mineral owner's position is.
Producing interests are valued off the actual checks and the field's decline, which in the Illinois Basin is slow and flat; a stripper well royalty that has paid for 40 years is a different asset from a shale well in its second year, and it should be priced like one. Non-producing acreage in the basin carries modest value unless it sits in an active waterflood or near a recent permit, and we will tell you which it is. Our mineral rights value page and value calculator show the approach.
Cypress and the other Chester sands, the workhorse of the basin: roughly 60 percent of the basin's oil has come out of Chesterian sandstones at a few thousand feet, in fields that have produced since the 1930s and 1940s.
The Valmeyeran carbonates and sands beneath the Chester, more than a fifth of basin production and the target of most waterflood and infill work in Clay City, Louden, and Salem.
Shallow sands along the La Salle anticline in the east, about 13 percent of basin oil, including the old Lawrence and Main Consolidated fields near the Indiana line.
Deeper carbonates, including the Geneva Dolomite, a smaller share of production but the deeper horizons that show up in old leases and depth severances.
The basin's source rock and the formation the state's horizontal fracturing law was written for. Permitted under the 2013 High Volume Horizontal Hydraulic Fracturing Act, but the basin has stayed a vertical, conventional province.
The top ten counties by 2025 production are listed first; White County alone is nearly a third of the state's oil. We buy in every producing Illinois county.
Whether you need a probate, the affidavit and transfer on death routes, the dormant mineral rules, and where unpaid royalties go: inherited mineral rights in Illinois, what heirs should do.
What Illinois mineral rights are worth, information only, with this month's activity. Unclaimed Illinois royalties: where the money goes and how an heir claims it.
Everything a Illinois owner needs in one place: who owns what under state law, how royalties must be paid and by when, what a buyer can and cannot deduct, the tax treatment of a sale, and the deadlines that quietly cost people their minerals. Free, and no sign-up.
Read the Illinois guideThe things owners here most often wish they had read first. All free, none of it gated.
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Prefer the phone? Call or text 918-984-1645 and you will get Stephen, the owner, not a call center. If we miss you, we text back the same day.
In a hurry? Text a photo of a royalty check stub to 918-984-1645 and our preliminary offer puts a written number in front of you within about two business days. It holds for 7 while you decide.