Historic Oil Field
Hamilton Dome, in Hot Springs County in the southwestern Bighorn Basin, is one of the largest and longest-producing fields in Wyoming. Oil was found on the structure in 1918, and the field has since delivered more than two hundred and fifty million barrels from the Tensleep and Phosphoria. It is a textbook secondary-recovery asset: a unitized reservoir kept pressurized by water injection, producing heavy sour crude at low rates that have persisted, decade after decade, long past the point where primary depletion alone would have ended it.
The discovery is credited to 1918 and to a physician named Hamilton, whose name the structure carries — a reminder of how much early Wyoming exploration was done by people outside the oil business who could read a surface fold. The dome is an asymmetrical anticline about seven miles long with roughly two thousand feet of structural closure, and drilling proved six producing strata between about fifteen hundred and thirty-five hundred feet. That combination of relief, shallow depth, and multiple pays made it one of the most attractive targets in the southern basin.
Unitization converted Hamilton Dome from a collection of competing leases into a single engineered reservoir, and water injection followed as the mechanism for holding pressure across the unit. The field today covers roughly fifty-nine hundred gross unitized acres. This is the step that separates the Bighorn Basin fields that survived from those that did not: pressure maintenance in the Tensleep and Phosphoria kept the recovery factor climbing long after the natural drive was spent, and it turned Hamilton Dome into a field measured in hundreds of millions of barrels.
Merit Energy Company has operated the field in recent years, and Evolution Petroleum acquired a non-operated position in it on November 1, 2019, holding roughly a twenty-four percent average net working interest with an associated twenty percent net revenue interest across about fourteen hundred net acres. Because the crude is heavy and sour, the oil is priced against the Western Canadian Select benchmark rather than against light sweet markers, which is why Hamilton Dome revenue can move differently from headline oil prices.
Hamilton Dome is an asymmetrical anticline roughly seven miles long with about two thousand feet of closure, on the southwestern side of the Bighorn Basin. Six producing strata have been identified between approximately fifteen hundred and thirty-five hundred feet, but the principal reservoirs are the Pennsylvanian Tensleep sandstone and the Permian Phosphoria. The crude is heavy and sour, which affects both the price it receives and the lift and handling costs of producing it. Shallow depth and strong structural closure are what allowed such a large accumulation to be found and developed so early.
Hamilton Dome is a secondary-recovery field in the strict sense: water injection wells pressurize the reservoir so that oil continues moving toward producers after natural drive has been exhausted. Run across a unitized area of roughly fifty-nine hundred gross acres, that program is what has carried cumulative production past two hundred and fifty million barrels. The result for owners is the flattest kind of decline curve in the oil business — output that changes little from year to year, governed by injection and by the price of a heavy sour crude rather than by new drilling.
Hamilton Dome royalties are long-life, low-volatility interests with a wrinkle: heavy sour crude priced off Western Canadian Select does not track headline oil prices, so revenue history here can look strange next to light-oil interests elsewhere. Value depends on remaining flood life, unit participation, and differentials, none of which show up in a simple income multiple. Interests are frequently held by heirs of century-old lessors. We buy minerals and royalties in Hot Springs County and provide free written offers.
County-level well data, production charts, and selling guides for the counties this field spans:
Because the field produces heavy sour crude, which is subject to Western Canadian Select pricing rather than a light sweet benchmark. The differential is a normal feature of this crude type, not an error in your statement, and it is one of the things a proper valuation has to account for.
Merit Energy Company has operated the unitized field in recent years. Evolution Petroleum acquired a non-operated working interest of roughly twenty-four percent on November 1, 2019, so more than one company holds an economic stake in the same wells.
Published figures put cumulative production in excess of two hundred and fifty million barrels since the 1918 discovery, which places it among the largest oil fields in Wyoming and among the most successful waterfloods in the Bighorn Basin.