It is now common knowledge in the industry that only about one third of the oil in known reservoirs will be recovered by present methods of production. Since 240 billion barrels of oil have been discovered and only 90 billion barrels are expected to be produced, the unrecovered oil in fields already discovered amounts to approximately 150 billion barrels. This tremendous quantity of oil is of great economic value and is the prize for those who devise new or improved methods for increasing recovery.

One approach being used by many to obtain some of these reserves is the use of heat and "in-situ" combustion as a recovery scheme. Such methods are particularly adaptable to viscous crudes which apparently cannot be recovered by any other known scheme.

A second and different approach is based on the fact that oil can be displaced completely by fluids miscible with it. Consequently, we are presently seeing great activity ill the-industry in the development and testing of a variety of miscible displacement schemes for increasing recovery. The most common of these which are now being field tested include high pressure gas displacement, condensing gas drive, and the LEG slug process. All of these methods require the use of pressure of the order of 1500 psi or higher. Unfortunately, most of the old Pennsylvania fields are shallow. The material in this paper describes some of the efforts of our laboratory to develop a type of miscible displacement which works at low pressures and so would be applicable to Pennsylvania oil fields. In particular, we have been working on the development of a relatively new modification of the miscible flood called the"Alcohol Slug Process." The work reported here describes this process, and discusses supporting studies which were performed to test or prove the validity of the laboratory work.

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