One Hundred Million Barrels of Oil From Block 31 Unit
Crane, Crane County, Texas
Marker Inscription
A discovery well completed in Nov. 1945 about a mile to the northeast has led to vast production of oil--one hundred million barrels by July 27, 1969. The discovery well, University A No.1 , was drilled by the Atlantic Richfield Company. This development is on land belonging to the University of Texas, designated as Block 31 Unit, and leased to Atlantic Richfield (the operator), Phillips Petroleum Company, Continental Oil Company and Champlin Petroleum Company. The unit--7,200 acres in area--has 72 wells approximately 8,500 feet deep, into the earth stratum known as the Devonian formation. Through the years, unusual processes were used to increase unit oil recovery. High pressure natural gas was injected, to wash oil from subterranean rock. Later, exhaust gas was injected instead of the costlier natural gas. Research and farsighted policies made possible unusually high recovery in this reservoir. Credit for the conservation and good management of this unit goes to the Texas Railroad Commission (as the regulatory body with oversight of oil production), the University of Texas and owners of the unit. (1969) supplemental plate added 1989: A second milestone was reached October 17, 1987, when the two hundred millionth barrel of crude oil was produced from the Block 31 Unit.
Erected by Texas Historical Commission
The Story
A discovery well completed in November 1945 opened one of the great oil fields of the Permian Basin, on University of Texas land designated the Block 31 Unit. By 1969 it had produced a hundred million barrels, and by 1987 a second hundred million, drawn from wells reaching some 8,500 feet into the ancient Devonian rock. Engineers pushed recovery far beyond the ordinary by injecting high-pressure gas to wash oil from the reservoir.
Why it matters
The field showcases the postwar oil technology and conservation practices that powered Texas and funded its university system.
The story behind this marker
AI contextThe era
When this field was discovered in November 1945, World War II had just ended, and the country was about to burn oil on a scale it never had before. Returning veterans bought cars, families moved to new suburbs, and highways and trucking spread across the map. The petroleum that had fueled the war effort was about to fuel a peacetime boom, and West Texas was one of the places it would come from.
The Permian Basin, the huge buried sea floor under this part of Texas and southeastern New Mexico, had already shown its riches in the 1920s. By the postwar years, drillers were reaching deeper than ever, chasing oil locked in older rock far below the shallower fields first tapped. The wells here went down about 8,500 feet into the Devonian formation, rock laid down hundreds of millions of years ago.
The land itself has a story too. Texas set aside large tracts of West Texas to support public higher education, and for decades they looked like little more than dry ranch country. Once oil turned up beneath them, those same acres became one of the most important sources of university money anywhere in the country.
People & events
The story starts with a single well, University A No. 1, completed about a mile northeast of this marker. The name tells you whose land it was on: the University of Texas. The tract, designated the Block 31 Unit, was leased to a group of oil companies, with one acting as operator. Over time it grew into a carefully managed field of about 72 wells spread across 7,200 acres.
The really interesting part came underground. Oil doesn't sit in a cave waiting to be pumped. It clings to the tiny pores of rock, and ordinary pumping leaves much of it behind. Engineers here forced high-pressure natural gas into the reservoir to wash oil out of the rock and push it toward the producing wells. Natural gas was valuable in its own right, though, so they later switched to exhaust gas, a cheaper stand-in that did similar work.
The results were counted in barrels. By July 27, 1969, the unit had produced one hundred million. The marker credits that success to research, farsighted policy, and shared stewardship by the Texas Railroad Commission, the University of Texas, and the unit's owners. Eighteen years later, on October 17, 1987, a supplemental plate recorded the next milestone: the two hundred millionth barrel.
Its place in the American story
Block 31 is a lesson in a part of the oil business that rarely makes headlines: getting more out of a field that has already been found. Early oil booms often drained reservoirs wastefully, letting pressure escape and stranding most of the oil underground. Gas injection, and the broader idea of managing a whole reservoir as one unit instead of a free-for-all of competing wells, was part of a shift toward conservation in American oil production. The marker states that shift plainly: credit for good management goes to regulators and owners working together.
The Texas Railroad Commission's oversight of oil production made it one of the most powerful regulatory bodies in the country for much of the 20th century, and fields like this one show what that oversight looked like on the ground.
There is a public story here as well. Because the oil lay under university land, its revenue helped build higher education in Texas. A barrel pumped from the Devonian rock beneath Crane County helped pay, in part, for classrooms and laboratories hundreds of miles away. Few places tie the oil patch to the lecture hall so directly.
If you visit
Crane is classic Permian Basin country: wide, flat, open land under a huge sky, with pump jacks nodding on the horizon. Standing at the marker, you're about a mile from the well that started it all, and on top of a reservoir that has produced hundreds of millions of barrels. You won't see any of that underground drama, but the scattered oilfield equipment around you hints at it.
Take a moment to picture what's happening thousands of feet below: gas pushed into ancient rock, oil slowly driven toward the wells. It's a good spot to talk with kids about how much engineering hides under an ordinary-looking landscape.
On a West Texas road trip, this marker fits naturally into a drive through the oil towns of the Permian Basin. Bring water, check your fuel before long stretches, and give yourself time. Distances out here are bigger than they look on a map, and the open country is part of the experience.
Written by AI to add context, grounded in the marker’s inscription and the historical record. The inscription above is the original, unaltered text.
Own a business near here? Add it to the map.
Themes & tags
Nearby & related markers
Odessa Telephone Exchange
Odessa, TX
Odessa's telephone exchange opened around 1897 in the early years of rural Texas telephony, when connecting far-flung ranches meant improvising with whatever ran across the land. Under pioneer rancher A. Quincy Cooper, service reached the countryside by stringing calls along barbed-wire fence lines. In a remarkable coincidence, Cooper's repair work on one such line in 1915 briefly broke into the first transcontinental telephone call between Alexander Graham Bell and his assistant, and the exchange was folded into Southwestern Bell in 1928.
Odessa Petrochemical Complex
Odessa, TX
In 1946 four West Texas oilmen founded the Odessa Natural Gasoline Company to capture the natural gas being flared away as waste in the oil fields. That gas proved ideal for making butadiene and styrene—the building blocks of synthetic rubber—and through the 1950s the Odessa Chamber of Commerce helped attract a cluster of plants that grew into what was then the largest petrochemical complex in the world. Firms like Shell, Rexene, and El Paso Products anchored an industry that reshaped the town.
The Cable Tool Rig
Odessa, TX
The cable tool rig, which dropped a heavy bit on a steel cable to pound its way downward, replaced the older spring-pole method and let drillers reach the deep formations of the Southwest. Introduced in Texas in 1866, it brought in the first great wells of the Permian Basin, including reconstruction from rigs used at the legendary Santa Rita No. 1, which blew in near Big Lake in May 1923. Texas pioneered much of the surrounding industry, from the first oil lease to the first pipeline and storage tanks.
El Paso Natural Gas Company's First Compressor Transmission Engine
Odessa, TX
This 800-horsepower Cooper-Bessemer compressor engine went to work in Culberson County in 1931 as the first machine of its kind at El Paso Natural Gas Company's original transmission station. Founded in 1928 by Houston attorney Paul Kayser, the company was among the earliest gas transmitters in the Permian Basin. Over 38 years of service the engine ran more than 152,000 hours and moved over 144 billion cubic feet of gas toward El Paso and the Southwest.