Marginal Wells: Fuel For Economic Growth
Enhanced Oil Recovery
U.S. oil production reached its peak in 1971 and has declined steadily since 1986. Enhanced oil recovery has been and will continue to be instrumental in recovering additional oil resources.
ere are two enhanced oil recovery methods: sec-
ondary and tertiary. e term “secondary recovery” generally refers to waterflooding or hydrocarbon gas re-injection. Reservoir pressure is increased, or main- tained, and oil is swept to the producing wells.
In older oil fields, reservoir pressure has diminished over time, decreasing the flow of oil. Secondary recovery operations permit the injection of a fluid, such as water or gas, into the formation. is in- creases the reservoir pressure and encourages the oil to flow more rapidly. In many states, the majority of marginal oil that was produced in 2006 was the result of secondary recovery methods. Out of states surveyed that track secondary recovery efforts, more than half of the marginal oil produced in Kentuck , Nebraska, South Dakota and Utah was recovered using this technique, while more than 90 percent of the oil in Alabama and Indiana was produced using this method. e table to the right highlights the survey responses.
“Tertiary recovery” follows waterflooding operations and generally involves the injection of a miscible
fluid. Carbon dioxide is such a miscible fluid. Tertiary recovery can be achieved by using several methods. In one commonly used EOR technique, carbon dioxide is injected into a reservoir. As the CO2 is injected it dissolves in the oil reducing the viscosity and surface tension of the oil droplets. e reduction in viscosity improves the flow rates of the remaining oil. Other techniques include thermal recover , which uses heat to improve the flow of the oil, and chemical injection. e IOGCC does not track the amount of marginal oil produced using tertiary recovery at this time.
e National Petroleum Council in its 2007 Global
Oil and Gas Study recommends the promotion of enhanced oil recovery by supporting regulatory streamlining and research and development pro- grams for marginal wells and by expediting permit- ting of EOR projects, pipelines and associated infra- structure. e study indicates the potential effect of this could be an additional 90 to 200 billion barrels of recoverable oil in the United States alone, which could help slow the current decline in production.
Marginal Oil Well Reserve
An oil resource is defined as a reserve when it is deemed economically recoverable. To date, there is no comprehensive measurement of the total amount of stripper oil reserve in the United States. e table to the right indicates estimates by a handful of IOGCC marginal oil well survey respondents.