Miscible Drive - Its Theory and Application

Abstract

Abstract Petroleum industry research organizations have for a number of years placed considerable emphasis on investigations regarding various techniques of recovering more oil from reservoirs. Out of this effort has emerged the miscible-drive process which to date shows great promise for future oil recovery operations. The process can actually be subdivided into several kinds of operations; however, the basic principle of all is that hydrocarbon materials such as propane, LPG, or gas are injected into a reservoir under such conditions that fluid capillary forces are reduced to zero and resultant displacement of oil is essentially complete in those pore spaces through which injected materials move. Consideration is given in this technique to subsequent recovery of valuable injected materials and to leaving the reservoir essentially filled with dry gas at abandonment. Success in application of these techniques will depend almost entirely on proper engineering and geological evaluation. The engineer must not only understand the basic principles involved in miscible-drive techniques, but also must recognize where various techniques are applicable and be able to cope with the many factors that require careful consideration to assure proper design and conduct of complicated operations such as these. This paper discusses the various miscible-drive techniques, their place in present day oil and gas operations, factors that require detailed consideration in determining their applicability and feasibility with regard to given reservoirs, and the approach to the application of these techniques to production operations. Introduction It has been recognized for a number of years that oil does not produce itself, but instead requires energy from some other source to cause the movement of oil to the wellbore where it is produced. The type and availability of energy will to a great degree determine the general magnitude of the percentage of the initial oil that can be produced through means inherent in the reservoir producing mechanism itself. Depending upon the source of energy, only a small or a large percentage of the oil may be produced. Average recovery expectancy of oil from all reservoirs in the U. S. by primary means has been placed in the order of about 35 per cent of initial oil in place. An enormous amount of oil is thus left in the reservoirs awaiting only the development of new methods of extraction before the petroleum industry can realize the recovery of a part of this residual oil left underground.