Enhanced Crude Oil Recovery Potential-An Estimate
Authors: Doscher T.M. , Wise F.A. 
Published: December 2007

Examination of recovery efficiency and distribution of oil in place in the U.S. indicates reservoir recovery efficiency has been quite static for many years. Superficial changes in efficiency have resulted from the sequence in which reservoirs have been discovered and the methods used to book supplemental reserves. Development of tertiary recovery schemes is seen to have comparable importance to exploration in frontier areas.

Introduction and Summary
Examination of published API data on domestic reserves of crude oil results in several interesting observations concerning the present status and future direction for the United States oil industry. Comparison of the low discovery rate of new reserves that the industry has experienced in the past - not with standing the discovery of Prudhoe Bay - with our present domestic demands for crude oil is striking. These discrepancies promise to have a dramatic effect on our domestic oil promise to have a dramatic effect on our domestic oil industry in years to come as the large fields discovered in the 1930's and 1940's are depleted. The foremost conclusion of this report, in common with that of many others, is that large, new domestic sources of crude oil need to be discovered and developed soon. Or, alternatively, an economically viable, massive substitute for domestic oil must be developed soon.
The second conclusion is that, contrary to many opinions, the cumulative oil reservoir recovery efficiency in the U.S. has been decreasing for a number of years, with the exception of a slight lift from the discovery of Prudhoe Bay. We can be certain that this is no way Prudhoe Bay. We can be certain that this is no way caused by poor or mediocre engineering, or by any arbitrary or poorly conceived decisions by management. The changes that have occurred in recovery efficiency with time are merely and exclusively caused by the sequence in which different types of oil fields were discovered in various locations in the U.S.
Study of the recovery-efficiency data has permitted us to reach some conclusions on the potential of tertiary recovery that we believe will be a shade better than those estimates that have been over-imbued with wishful thinking. The API data leave little doubt that there is and will be a very large amount of oil discovered that will not be produced with the technology we have developed to date. Thus, a third conclusion is that in addition to the need for large, new domestic sources of petroleum to be discovered, there is a potential for a petroleum to be discovered, there is a potential for a sizable addition to domestic reserves if recovery efficiency can be increased. It becomes apparent, however, that the tertiary recovery potential cannot be quantified at this time, although targets can be spelled out. Were we faced with definitive success today in experimental and pilot operations, the time frame required for execution of the projects would make 1 million B/D by 1990 a difficult target.

Recovery Efficiency Retrospective Analysis
Fig. 1 relates the 1973 estimates of ultimate recovery of crude oil reservoirs to their year of discovery; that is, reserves are attributed to the year in which the field was discovered even though development and additions to reserves from the field were continued in subsequent years. The data are not complete for the last few years because development drilling and evaluation is still under way, but the trend is incontrovertible.
P. 575