Midway-Sunset is the largest oil field in California and one of the largest in the United States, stretching roughly 25 miles along the southwestern edge of the San Joaquin Valley near Taft and Fellows in Kern County. Discovered in 1894, it has produced close to four billion barrels of heavy crude, nearly all of it recovered with steam. Thousands of closely spaced wells still lift oil from shallow sands here, which means royalty checks in this field trace back to one of the longest-lived production machines in American oil.
Commercial production at Midway-Sunset dates to 1894, when shallow wells near present-day Maricopa found heavy oil in the sunbaked hills of southwestern Kern County. The field grew slowly until the boom years of 1908 to 1914, when gushers like Lakeview No. 1 — which flowed uncontrolled for 18 months beginning in 1910 — made the Midway district world famous and pulled dozens of companies into the play.
Because Midway-Sunset crude is heavy, typically around 11 to 14 degrees API, primary recovery left most of the oil in the ground. Operators began experimenting with thermal recovery in the 1960s, and by the 1980s cyclic steaming and steam drives had transformed the field. Production peaked near 160,000 barrels per day in the early 1990s, decades after many observers had written the field off.
Ownership consolidated over the decades into a handful of large thermal operators, including Aera Energy — the Shell and ExxonMobil joint venture that became part of California Resources Corporation in the 2024 merger — along with Berry and other independents. With total oil in place estimated in the tens of billions of barrels, Midway-Sunset remains an actively steamed field with a deep remaining resource.
Midway-Sunset produces from a stacked series of shallow Miocene through Pleistocene reservoirs along the folded and faulted western margin of the San Joaquin Basin. Key producing zones include the Potter, Monarch, and other sands of the Monterey Formation, plus the overlying Etchegoin and Tulare sections. Traps are a complex mix of anticlines, stratigraphic pinch-outs, and tar seals, generally at depths of a few hundred to roughly 3,000 feet. The oil is heavy and viscous, which is why reservoir temperature — not just reservoir pressure — controls recovery.
Nearly all Midway-Sunset production depends on steam. Operators use cyclic steaming, where a well is injected, soaked, and returned to production, and continuous steam drives that push heated oil toward producers. Heating the reservoir thins the crude enough to flow, so royalty volumes track steam programs: when injection is active, decline curves flatten or reverse. In California, steam projects run under CalGEM underground injection permits, and rules such as the state setback law for wells near homes and schools shape where new work occurs. For owners, the practical point is that these barrels are manufactured with heat, capital, and permits.
Midway-Sunset royalties are unusual assets: shallow declines, century-long production history, and a resource base that has outlasted every prediction of its end. Valuation should reflect steam economics, operator activity on your specific leases, and California’s permitting environment, which realistically constrains how much new drilling supplements existing wells. Owners weighing hold versus sell deserve numbers grounded in those specifics rather than a generic multiple of last month’s check. We buy minerals and royalties in Kern County and provide free written offers.
County-level well data, production charts, and selling guides for the counties this field spans:
The field is a heavy-oil steam flood, so production declines slowly compared with conventional wells, and payments often continue for decades. The trade-off is that volumes depend on the operator continuing to inject steam, which is a capital and permitting decision made year by year.
Not necessarily. Checks in steam-flood fields move with oil prices, steam cycles, and lease-level operating decisions as much as with reservoir depletion. A review of your specific leases and the operator’s recent activity tells you far more than the trend of a few statements.
Gather a recent check stub or division order showing the operator, lease names, and your decimal interest. With that information we can evaluate the underlying wells and provide a free written offer, with no obligation to accept.