Historic Oil Field
Greater Aneth is Utah’s largest oil field, discovered in 1956 in southeastern San Juan County near the Four Corners. It produces from carbonate buildups in the Desert Creek and Ismay zones of the Pennsylvanian Paradox Formation, sealed by the Gothic shale, and has yielded well over 450 million barrels. The field has been waterflooded since the early 1960s and later placed under carbon dioxide injection in a water-alternating-gas scheme. Much of the field lies on Navajo Nation trust land, which makes the mineral ownership picture here different from most oil fields — an important distinction for anyone researching interests in the area.
Exploration of the Paradox Basin accelerated in the early 1950s, and the 1956 discovery at Aneth proved that the Pennsylvanian Paradox Formation held carbonate buildups capable of giant accumulations. Development came quickly across a broad area that was ultimately organized into several units — the Aneth, McElmo Creek, Ratherford, and White Mesa areas among them — collectively called Greater Aneth. Within a few years the field was Utah’s dominant oil producer, and the remote Four Corners country around the town of Aneth was rebuilt around tank batteries, gathering lines, and a gas plant.
Primary recovery in the Desert Creek buildups was limited, and operators moved to secondary recovery early. Water injection began in the units in the early 1960s, restoring pressure and displacing oil through the porous carbonate. Decades later, carbon dioxide was added: injected in alternating slugs with water, CO2 mixes with residual oil that waterflooding leaves behind. The combination has kept the field producing for roughly seventy years, and Greater Aneth has since been studied as a candidate for combined enhanced oil recovery and geologic carbon dioxide storage.
Ownership and operation reflect the field’s setting on the Navajo Nation. Navajo Nation Oil and Gas Company describes the Greater Aneth area as the largest producing oil field in Utah, with several thousand barrels a day from a few hundred wells across the units it holds. Royalty revenue from the Utah portion of the reservation has long been the subject of federal and state trust arrangements benefiting Navajo residents of San Juan County, and those arrangements — rather than ordinary private mineral conveyancing — govern much of the mineral estate here.
Greater Aneth produces from the Paradox Formation of Pennsylvanian (Desmoinesian) age, specifically the Desert Creek zone with additional pay in the Ismay. The reservoirs are algal and skeletal carbonate buildups — mounds that grew on shallow shelf areas within the evaporite-rich Paradox Basin — with porosity concentrated in the mound facies and degrading rapidly off-structure. The overlying Gothic shale forms an effective seal, which is one reason the field has been evaluated for carbon dioxide storage. Because pay quality follows the mound geometry, well performance across the field varies with position on those buildups rather than with regional structure.
Two mechanisms have carried Greater Aneth past primary depletion. Waterflooding, in place in the units since the early 1960s, repressured the carbonate and swept mobile oil toward producers. Carbon dioxide injection followed, run as a water-alternating-gas process so that CO2 contacts residual oil while water controls its mobility through the high-permeability mound facies. The field’s combination of a mature flood, a proven seal in the Gothic shale, and a long injection history has made it a study subject for pairing enhanced recovery with permanent carbon dioxide storage — an unusual profile for a field of this age.
Mineral ownership at Greater Aneth is not typical. Much of the field sits on Navajo Nation trust land, where the mineral estate is held in trust and leased through the Nation and the Bureau of Indian Affairs; trust and restricted interests are not conventional fee minerals, are not freely conveyable, and are not something we purchase. Our work in San Juan County is with fee mineral and royalty owners on non-trust lands in the surrounding area. If that describes your interest, we buy minerals and royalties in San Juan County and provide free written offers.
County-level well data, production charts, and selling guides for the counties this field spans:
No. Trust and restricted Indian mineral interests are held by the United States for the benefit of the Nation or of individual allottees, and they are leased through the tribe and the Bureau of Indian Affairs under federal law rather than sold like private minerals. Anyone suggesting otherwise is describing something different from what those interests actually are. We do not purchase them.
The chain of title and the land status tell you. Fee minerals appear in county records with ordinary deeds and are typically leased by private lease; trust and allotted interests are administered federally and appear in BIA records instead. If you are unsure, send us your documents and legal description and we will tell you what your paperwork indicates before anything else is discussed.
Chiefly the decimal, the specific unit or lease your acreage participates in, and how long injection is likely to continue being funded. Flooded carbonate fields decline slowly but depend on sustained investment. A written offer should show those assumptions rather than presenting a single number, which is how we prepare ours.