Current Status of Steam Injection As a Heavy Oil Recovery Method

Abstract

Abstract Steam injection both cyclic and continuous, has been extensively employed for the recovery of heavy oil in the United States, Canada and Venezuela with mixed success. This study view the current status and the future potential of steam injection as an oil recovery process, am1 its economics on relation to in-situ combustion. A comprehensive survey of the steam injection tests conducted so far is presented, based on published reports. Cyclic steam injection, steamflooding and hot waterflooding projects are covered. A number of unsuccessful tests are also mentioned, in order to delineate the cordinations under which steam injection is likely to be successful. The result of all project are listed, and they are used To develop certain correlations which may be helpful in designing a field project. Economics of the steam injection processes and special operational problems, together with remedial measures, are also discussed. Introduction STEAM AND HOT WATER INJECTION have been employed as oil well stimulation methods for many years, as the existing technical and patent literature shows. Steam stimulation, following its accidental discovery, gained widespread popularity because of its attractive feature of rapid payout and its effectiveness as a recovery method in heavy oil reservoirs with marginal or zero oil production rates. Steamflooding, or continuous steam injection is relatively new and only recently have its advantages come to be recognized. The present article gives the principal statistics of selected steam stimulation, steamflood and hot waterflood field tests. An attempt is made to obtain useful correlations from these data, and thus derive general criteria for steam stimulation and steamflooding. The two processes are compared and contrasted. Operational problems are briefly outlined, together with remedial measures employed in the field. Finally, the economics of steam injection are disclosed. It should be noted that this article does not discuss the great mass of literature on laboratory studies and theoretical investigations of steam and hot water injection: not does it deal with the operational aspects of steam injection, such as well completions, surface and downhole equipment, etc. Mechanism of Oil Recovery by Steam Injection Before reviewing- the field test statistics, it is instructive to consider briefly the principal mechanistic features of cyclic steam stimulation and steamflooding. In cyclic steam stimulation, the primary objective is to lower oil viscosity, with some thermal expansion of oil, the drive energy being supplied by reservoir pressure, gravity, compaction, solution gas drive, etc. As a result, the oil production response would vary greatly, depending on the reservoir energy. In the case of thick, steeply dipping sands (as in California l. gravity drainage is the dominant oil expulsion mechanism. In the Bolivar Coast fields of Venezuela, formation compaction plays an important role in oil recovery. In thinner, flat-lying formations, such as those of Western Canada, solution gas drive is the main mechanism.