The Fullerton Field in northwestern Andrews County, Texas is one of the Permian Basin’s premier Clearfork accumulations — discovered in 1942 and developed into the giant Fullerton Clearfork Unit, a waterflood that has anchored the area’s production for nearly seventy years. The field produces primarily from the lower Clearfork, an early Permian dolomite, with additional pay in the overlying Wichita-Albany interval. Roughly 300 million barrels of cumulative recovery and a famously flat, flood-supported production history make Fullerton acreage a textbook long-life royalty asset.
Source: Texas Railroad Commission production filings, aggregated across RRC field designations 33230001, 33230500, 33230900, 33230300. Reported volumes lag the calendar by several months.
Fullerton was discovered in 1942, opening the Clearfork play on the northwestern corner of Andrews County during the wartime drilling push. Development proceeded rapidly through the 1940s as operators delineated a large, low-relief carbonate accumulation, and Humble Oil & Refining emerged as the field’s principal developer. The town of Fullerton grew up as a company camp serving the field, one of the last of the classic West Texas oil communities.
The field’s defining event was unitization: the Fullerton Clearfork Unit was formed in the mid-1950s and waterflooding was initiated in 1956, converting a pressure-depleted primary field into a managed injection project. The flood worked. Unit production was maintained between 11,000 and 16,000 barrels of oil per day from the mid-1970s onward even as water handling grew enormously — a performance that made Fullerton a standard reference case for Clearfork waterflood management.
Exxon, Humble’s successor, operated the unit for decades and used it as a laboratory for low-permeability carbonate recovery, with the Bureau of Economic Geology later conducting a major reservoir-characterization study of the field. In the modern era the unit has been associated with ExxonMobil’s XTO Energy organization, and the field continues as a large, mature waterflood with substantial remaining oil in place targeted by infill and recompletion work.
Fullerton produces primarily from the lower Clearfork, an early Permian dolomite deposited on a shallow carbonate shelf, with additional pay in the Wichita-Albany section. Clearfork reservoirs are notoriously heterogeneous — low-permeability dolomite with porosity distributed in thin, discontinuous layers — which limits primary recovery to a small fraction of the oil in place. That same rock character is why Fullerton rewarded careful pattern waterflooding for decades and why reservoir studies keep identifying bypassed oil: the field’s remaining resource is a function of geology, not exhaustion.
Fullerton’s recovery story is one of the Permian’s great sustained waterfloods. Injection began in 1956 within the giant Fullerton Clearfork Unit, and disciplined pattern management held unit output remarkably steady for decades — the signature of a flood recovering oil the primary era could not touch. Low-permeability Clearfork rock gives up its oil slowly, which cuts both ways: recovery factors are modest, but decline is gentle and the economic tail is very long. For royalty owners, that means Fullerton checks have historically been about persistence, not spikes.
A mineral or royalty interest in the Fullerton area is a stake in a unitized flood with nearly seventy years of injection history and a demonstrated ability to produce steadily at scale. Interests like these are frequently undervalued by buyers who apply steep-decline assumptions built for shale to a field that declines like a glacier. Understanding your unit decimal and the flood’s track record is the foundation of any fair sale. We buy minerals and royalties in Andrews County and provide free written offers.
County-level well data, production charts, and selling guides for the counties this field spans:
Yes. The Fullerton Clearfork Unit has been under continuous waterflood since 1956 and remains an active, large-scale mature flood, with ongoing infill and recompletion work targeting the substantial oil still in place.
Humble Oil developed the field after its 1942 discovery, and successor Exxon operated the unit for decades. In the modern era the unit has been associated with XTO Energy, ExxonMobil’s conventional-asset organization.
Your decimal interest in the unit, current unit production and pricing, and the shallow decline profile characteristic of Clearfork waterfloods. A fair offer prices the long tail — request a free written offer and compare it against your recent statements.