Analysis of Enhanced-Oil Recovery Potential in Ohio

In terms of the international petroleum industry, Ohio is considered part of a mature hydrocarbon basin; that is, most of the petroleum reservoirs are thought to have been discovered and most of the primary production has been recovered from those reservoirs. Although much exploration continues today in Ohio, especially in the deeper Ordovician- and Cambrian-age strata, the mature status does apply for most of the shallow reservoirs in our state. Most of the best production areas from the shallower horizons have been defined and developed. Primary production in many of the larger "Clinton" and Berea Sandstone fields developed in the 1960s through the early 1980s is now in decline.

A number of companies are engaged in or considering secondary oil recovery in Ohio's declining or abandoned fields using enhanced-recovery technologies. Some feel that Ohio is past due for a concerted effort to increase production through enhanced-recovery projects (EPRs). Ohio's current production from ERP's accounts for less than 5 percent of the state's total yearly oil production, whereas in some surrounding states, secondary recovery accounts for approximately 25 to 50 percent of total production.

Enhanced-recovery techniques have been developing almost as long as the oil industry has been in existence. Ohio was an early innovator in secondary recovery technologies. Depending upon the process used, an operator may expect to recover from ½ to more than 1 barrel of secondary oil for produced more than 1 billion barrels of oil since 1860, so there is no lack of ERP prospects to be examined.

One of the earliest attempts at secondary recovery in Ohio was conducted in 1911 by the Cumberland Oil Company and I. L. Dunn in the Chesterhill field in Morgan County. The Pennsylvanian "Cow Run" sand, at a depth of 400 feet, was repressurized using compressed air. By 1917, about 4,000 wells were affected by this process, termed the Smith-Dunn or Marietta compressed-air process. It is estimated that 80 percent of the projects were successful, and an average increase of 33/2 times the rate of production was realized from the repressuring began. The largest repressuring project was in the Sistersville field in Monroe County, where gas was injected in 19 injection wells beginning in 1933. The daily production rate of 374 wells was slowly increased from 124 barrels of oil per day to a peak of 337 barrels of oil per day in 1939, when a slow decline began.

Waterflood technology got its start in the giant Bradford field of northwestern Pennsylvania in the 1930's. As soon as the Ohio legislature legalized waterflooding of oil sands in 1939, waterflooding of the shallow Mississippian Berea Sandstone was attempted in the Chatham field in Medina County. By 1949, 325 injection wells and 392 producing wells were producing 650 barrels of oil per day. Estimated total flood production from the field was 2,250,000 barrels of oil. Active waterflooding continued into the 1960's, and it is conservatively estimated that in excess of 5,000,000 barrels of oil have been recovered from the Chatham field.

As of early 1995, 43 enhanced-recovery projects are active in Ohio. Approximately 700,000 barrels of water were injected in 1994. Some of the more significant enhanced-recovery activities include:

• The Quaker State Corporation Berea Sandstone (Mississippian) waterflood in Ashland County. This project was initiated in 1974 with 123 injection wells and 116 production wells; 4,109,845 barrels of water have been injected since 1982. Estimated cumulative oil production exceeds Estimated cumulative oil production exceeds 2,000,000 barrels.
   
• The Mitchell Energy Corporation Pennsylvanian sandstone waterflood in Lawrence County. Since 1991, 375,000 barrels of water have been injected in 17 wells. By 1993, when the full flood effects were realized, 49,349 barrels of oil per year had been produced from 25 wells, representing 2.7 times the production anticipated by the normal field-decline curve.
   
• The Baldwin & Baldwin (formerly owned by Sun Oil Company) waterflood of the "Krysik" sandstone (Cambrian) in Erie County. Primary production was more than 600,000 barrels when waterflooding began in 1974; 2,178,435 barrels of water have been injected since 1982. Estimated total cumulative production is 1,500,000 barrels of oil.
   
• The Oxford Oil Company (formerly Preston Oil Company) "Clinton" sandstone (Silurian) in Coshocton County. This project was initiated in 1965. Yearly production was 680 barrels of oil in 1965 and increased to 4,848 barrels by 1968. Cumulative production by 1971 from seven wells was 370,000 barrels. Production continued through 1994.