The Big Lake Oil Company was chartered under the laws of Delaware by Michael L. Benedum in Pittsburgh, Pennsylvania, on October 5, 1923, to acquire and develop a 10,000-acre lease on University of Texas land in Reagan County, in what became the Big Lake oilfield. The land, which included the Santa Rita Oil Well, had been owned by Frank T. Pickrell and associates, who had formed the Texon Oil and Land Company in 1919. Pickrell sold tracts of Texon's oilfields to Benedum for $200,000 and a quarter share in the Big Lake Oil Company. The new company operated with Levi Smith as president and Pickrell as vice president. On October 19, 1923, Benedum and his associates formed the Plymouth Oil Company as a parent company that managed BLOC. Walter S. Hallanan was president of Plymouth, and Jerome G. Farquaher was vice president. The BLOC immediately assumed operation of Santa Rita No. 1 and the Texon Company's test wells two and three. By late 1923, four more wells were underway, and the BLOC opened an office in San Angelo. In February 1924, ten wells were being drilled, and in March, a well was begun using rotary tools, a first for West Texas, where cable tools had dominated. In May a rig burned and was replaced with the first steel derrick. After several dry holes, well number 9 began flowing at seventy barrels an hour and assured the field. By May 1926, BLOC had sixty producing wells. As the BLOC expanded, it also built Texon, a town for its employees, including a water system and an ice plant. Pipelines, tank-loading racks, a tank farm for oil storage, and an oil-treating plant were built. Electrification of the field was started immediately, and by 1927, with current furnished by the Pecos Valley Power and Light Company, the BLOC field was among the nation's earliest to be fully electrified. In 1941, the BLOC built its own power plant for the field and Texon. In April 1925 the BLOC completed a casing-head gasoline plant to convert wellhead gas to gasoline, all of which was snipped to the Humble refinery at Baytown. In 1930 the plant was enlarged and a gas line built to supply San Angelo; in 1936, it was converted to recycling. An explosion and fire ended operations in 1951.
Lack of an outlet for the steadily increasing production of the field caused the BLOC and the adjoining Texon Company to conclude, in October 1924, an agreement with the Marland Oil Company to join in organizing the Reagan County Purchasing Company to transport the bulk of its crude to market. The BLOC continued its drilling program through the 1930s and 1940s, and although a few wells were drilled in the 1950s, by 1954 the field was primarily a pumping operation. The Big Lake field was unique in that never before had one company ever held all the leases on such a large area. Throughout its existence, the BLOC applied the most modern business and conservation practices. Because of its concern for the welfare of its workers and their families, the company enjoyed the reputation of being an ideal employer. Opening of the Santa Rita well and development of the BLOC field brought growth to several towns within a hundred-mile radius, opened the Permian Basin for exploration, and produced immense wealth for the University of Texas. In 1962 Plymouth Oil Company was sold to Marathon Oil Company, which continued to operate the Big Lake oilfield.