Conroe field is an elliptical-shaped oil-producing area in south central Montgomery County. It was discovered by a young wildcatter, George W. Strake, but its development was the quick work of Humble Oil and Refining Company (now Exxon), the Texas Company (Texaco), and a number of independents. The original field drew production from an average depth of 5,050 feet in the Upper Cockfield and Main Conroe sands, which overlie a deep-seated, faulted salt dome of Eocene age. The source of primary recovery was a strong water drive and gas-cap expansion. Reservoir pressure has been closely observed since April 1933 and has been maintained by gas and water injections, obviating the need for secondary recovery. Between its discovery on December 13, 1931, and January 1, 1993, the field produced more than 717 million barrels of oil. Although the field held large volumes of gas, many early operators regarded gas as a nuisance and a danger and wasted it through venting or flaring until 1935, when the practice became illegal. The field is significant because its flush production reestablished the Texas Gulf Coast as a major oil-producing province after thirty years of intensive prospecting. Conroe field was named for the county seat, situated five miles to the southeast.
Several early exploration attempts in the area of Conroe field proved unsuccessful before and during the 1920s. Gas seeps on the Rhodes farm in Montgomery County captured the interest of a number of local amateur oilmen as early as 1919. They formed Crystal Creek Oil Company and consolidated a block of 5,000 acres in and around the Ransom house survey. Although the acreage later proved to be a part of Conroe field, the company could not finance the drilling of a test and dropped the leases. In 1924 El Saline Petroleum Company No. 1 Outlaw was staked in the G. W. Wagers survey and drilled to 1,961 feet. Finding only gas, the operators abandoned it. The Kelly-Barker No. 1 Juergens was staked in the D. James survey two miles west of Conroe in 1929. Drilling to a depth of 3,662 feet encountered no oil. In January 1930 the No. 1 Juergens was junked.
Although amateurs and independents had found no production in the area, several major oil companies took leases and began geophysical studies there. After refraction seismography and torsion balance were used, no oil-bearing structure was found and most of the leases were allowed to expire. Although seismography was important to Gulf Coast exploration by the late 1920s, it offered no evidence of the deep-seated domal structure. That evidence came from a wildcat well drilled by George W. Strake, who became interested in the area. He put together a block of 9,300 acres and spudded a poor-boy well, the Strake No. 1 South Texas Development Company, in the Theo Slade survey on August 30, 1931. He drilled the well to a depth of 5,033 feet, where it began to spray fifteen million cubic feet of gas and 200 barrels of condensate a day. The discovery was given little attention because it produced only gas and condensate and because oilmen regarded the Cockfield sands as unproductive. At the end of 1931, Conroe field reported annual production of 1,000 barrels of oil from one well. Although Strake had found oil, he still had no money to develop the field. In March 1932 his company, Strake Oil Corporation, contracted with Humble Oil and Refining Company. Strake Oil assigned six leases to the major company for $100,000 and agreed to drill four wells for Humble to a depth of 5,500 feet at a maximum cost of $50,000 each. Strake Oil brought in the No. 2 South Texas Development Company, staked 2,400 feet south of the No. 1, at a depth of 5,026 feet on June 5, 1932. It flowed 900 barrels of oil a day and was considered the discovery well in the Conroe field because it sank into the Main Conroe sand and produced large quantities of oil. Although there were other operators in the field, Strake and Humble delayed the drilling of additional wells for several months.
One reason for delayed development by Strake and Humble may have been the emergency proration rules set up in the field by the Railroad Commission of Texas when only five wells had found production. The regulations covered drilling practices, casing procedure, and well spacing, all designed to preserve the highly unstable reservoir. The gas-charged shallow sands and the deeper soft, unconsolidated domal formation made drilling and development risky. Several wells in the field cratered. The rig in one instance and the Christmas tree in another sank out of sight into their holes. Several wells caught fire. There were blowouts in a number of wells. Water, mud, and cement were pumped into difficult wells to stabilize them. Relief holes were drilled to minimize the force of reservoir gas. But it was the Harrison and Abercrombie Oil Company No. 1 M. H. Alexander, located in the John McHorse survey, that caused a major problem for all field operators.
The No. 1 Alexander was completed to a total depth of 5,094 feet and flowed 120 barrels of oil in its first hour on December 12, 1932. At the end of 1932 the field had sixty drilling rigs at work and reported an annual production of 2,630,000 barrels of oil. But early in January 1933 as the field was poised for the greatest year of its development, the No. 1 Alexander cratered when the casing, well-head connections, and tubing began to sink. The casing split and the well began to flow out of control. A short time later, the hole bridged over and production decreased to an estimated ten barrels a day. By March the No. 1 Alexander was quiet, and flush field production began as 258 wells flowed oil and sixty-two rigs drilled for new oil. As development in the field continued, the Railroad Commission temporarily separated the Upper Cockfield sand production from the main field and set the Cockfield allowable at 10,000 barrels of oil a day. Daily allowable for the main field was fixed on June 1, 1933, at 60,000 barrels of oil, based 50 percent on acreage and 50 percent on potential, on twenty-acre units. Although operators agreed to the regulations, they were unprepared for the events of June 20, 1933. On that day the No. 1 Alexander roared to life again when the bridge that checked its wild production gave way, allowing unrestricted flow. On August 10, 1933, with the field only 57 ½ percent developed and with the renegade well gushing, production reached a peak daily flow of 92,000 barrels of oil, exceeding its allowable by 32,000 barrels. As late as September 13 the runaway well continued to shower the countryside with nearly 11,000 barrels of oil daily as pumps were installed to skim the oil from the surface for storage. Since the No. 1 Alexander was using its own allowable in addition to that of other wells, operators petitioned the Railroad Commission to increase field allowable to assure them their proportion of production. The request was denied because the depression economy could not absorb the great volume of oil. The commission actually reduced the field allowable by the end of 1933. With their petition rejected, field operators realized that any solution to the problem of the No. 1 Alexander had to come from their own initiative. In October 1933 Humble, aided by several other operators, made a deal with Harrison and Abercrombie by which Humble agreed to pay the owners of the fugitive well $300,000 cash for the privilege of killing it in the producing horizon. Harrison and Abercrombie would continue to own all oil produced from the No. 1 Alexander above the well allowable. If the well were not killed, it would remain the property of Harrison and Abercrombie. If the plan were successful, Harrison and Abercrombie would assign to Humble the fifteen acres surrounding the No. 1 Alexander. It was estimated that Humble spent $365,000 to drill a relief well, kill the outlaw well, and preserve the reservoir by January 16, 1934. The crater of the No. 1 Alexander was estimated to be 600 feet deep and 200 feet wide at the top. The well had produced more than 1,250,000 barrels of oil.
In 1933, the year of its greatest development, the field produced 21,483,279 barrels of oil from 679 wells-ten times more than in 1932. A large part of production left the field by pipeline. Eight gathering systems took crude to two trunk lines owned by Tide Water Pipe Line Company and Channel Transport and Pipe Line Company, which linked Conroe field with the Houston Ship Channel. Three other pipelines, operated by Humble Pipe Line Company, Texas Pipe Line Company, and Sun Pipe Line Company, carried crude to refineries owned by the parent companies. In the field, Strake had constructed Conroe Refining Company to handle a daily capacity of 250 barrels of oil, and several other small refineries were under construction at year's end. Two gas plants operated in the field-Humble, with a daily capacity of 6.72 million cubic feet, and Midland, with a daily capacity of 12.5 million cubic feet.
By early 1934 the field was in the last stage of development and covered 17,000 proved acres. During the year six gas wells were completed and daily gas production for the field reached thirty million cubic feet. Oil-well drilling declined during the year as operators observed the twenty-acre spacing rule. In 1934 crude production declined to 17,761,000 barrels. Throughout the remainder of the decade, it generally slipped downward as gas production climbed. By the end of 1941, after ten years of production, Conroe field reported an increased annual gas yield to 1,598,942,000 cubic feet from thirteen wells, while crude figures slid to 11,614,880 barrels. By 1942, with the increased wartime demand for crude, production rose, and by 1944 crude yields soared to an all-time annual high of 23,207,917 barrels of oil as gas production surged to 2,930,385,000 cubic feet. At the end of the war, crude production began a general downward trend as gas production maintained or escalated yields. By the end of 1951, after twenty years of production, the field reported yearly yields of 13,989,299 barrels of oil and 5,226,669,000 cubic feet of gas. On August 1, 1956, the commission permanently separated the Upper Cockfield formation into a new field by that name, leaving production from the Main Conroe sands in the original field. Throughout the 1960s the mature field continued reduced crude and enlarged gas production. At the end of 1971 new short-lived production improved annual yields of both oil and gas. In 1978 Conroe field was unitized, retaining the twenty-acre spacing. By the 1990s the field no longer produced dry gas or condensate, but its cumulative gas yield since 1970 was 16,403,142,000 cubic feet. By January 1, 1993, the field that reestablished the Gulf Coast region as an oil province reported cumulative crude production of 717,258,952 barrels.