The Frio Deep-Seated Salt Dome fields lie south and southeast of Houston in Brazoria, Fort Bend, Harris, Galveston, and Chambers counties along the Texas coast. Located on domal structures, the fields are divided into small segments by closely spaced faults that block fluid communications in the subsurface. To recover oil from the segmented reservoirs explorationists established a large number of individual fields. Some had meager cumulative yields and were depleted within a few years, but some were still producing after decades, drawing prolific yields from larger reservoirs. Collectively, the Frio Deep-Seated Salt Dome fields are significant because their cumulative yields exceed those of any other producing formation in southeast Texas. By 1982 the fields reported a combined cumulative production in excess of 2.3 billion barrels of oil, and at the end of 1993 the figure surpassed 2.4 billion barrels.
Exploration in the area of the Frio Deep-Seated Salt Dome fields began as early as 1924, when Gulf Production Company took leases that were 4½ miles southeast of Sugar Land in Fort Bend County and completed refraction seismic work. The seismic missed the dome, however, and Gulf dropped the acreage. H. C. Cockburn acquired the leases and used torsion balance to find evidence of the dome in 1926. Cockburn sold the idea and the leases to Humble Oil and Refining Company (later Exxon Company, U.S.A.). After taking additional contiguous leases, Humble spudded the No. 1 Sugar Land Industries, which was completed on March 27, 1928, at a total depth of 3,536 feet in a Frio sand. Initial production was 1,000 barrels of oil per day. With the success at Sugar Land field, explorationists searched for similar fields in Fort Bend and the surrounding counties of southeast Texas. Other fields that added to the play in the early 1930s were Thompson Frio (Fort Bend County, 1931), Manvel F. B. I Oligocene (Brazoria County, 1933), East Hastings Upper Frio (Galveston County, 1934), West Hastings Frio (Brazoria County, 1934), and Manvel F. B. II Oligocene (Brazoria County, 1934). In 1935 five more fields were brought in: Anahuac Main Frio and Turtle Bay Middleton in Chambers County, Gillock Big Gas in Galveston County, and South Houston Frio and South Houston Miocene in Harris County. Before the end of the decade seven additional Frio fields were found. They were Webster Upper Frio (Harris County, 1937), Cedar Point Frio 5900 (Chambers County, 1938), Cedar Lake Frio (Harris County, 1938), South Gillock Big Gas (Galveston County, 1939), and North Thompson Upper Vicksburg, South Thompson 4400, and South Thompson 5400 (all Fort Bend County, 1939). Of the fields discovered in the 1930s, the most prolific in cumulative barrels of oil by 1982 were West Hastings Frio (534 million), Webster Upper Frio (528 million), Thompson Frio (325 million), Anahuac Main Frio (227 million), and East Hastings Upper Frio (112 million).
Although the most prolific fields were found in the 1930s, development of the play continued into the 1940s and 1950s and centered in Chambers and Brazoria counties with more field discoveries. Among the most important fields were Fig Ridge Seabreeze and Oyster Bayou Seabreeze (both Chambers County, 1941) and Gillock East Segment (Galveston County, 1949). In the 1950s three new areas became productive and were called Chocolate Bayou Upper Frio (Brazoria County, 1950), Trinity Bay Frio 12 (Chambers County, 1951), and Chocolate Bayou Alibel (Brazoria County, 1952). By 1982 three of those fields that were brought into production in the 1940s and 1950s reported impressive cumulative yields in barrels-Oyster Bayou Seabreeze (127 million), Fig Ridge Seabreeze (43.5 million), and Trinity Bay Frio 12 (21.2 million). Although the important Frio Deep-Seated Salt Dome fields were found before 1960, exploration continued through the 1980s with the discovery of many insignificant fields that were drained of their meager reserves within a short time.
The sources of primary recovery in the Frio Deep-Seated Salt Dome fields were strong water drives and gas-cap expansion. Many of the fields were operated under cooperative management to maximize primary recovery. Others were unitized for secondary recovery and have initiated reservoir-wide gas-injection projects. Still others have begun less common forms of secondary recovery to stimulate weak water drives. Infill drilling was employed selectively in some fields, enhancing their ultimate yields. By 1982 engineers set recoverable reserves for Frio reservoirs of the deep-domes play at nearly 4 billion barrels of oil. By the end of 1993 the fields had yielded more than 2.4 billion barrels.