Foam Field Tests: State of the Art and Critical Review

Abstract

This paper gives a current overview of field experience with the use of foam for improved recovery and a ciitical evaluation of selected pilot projects. The focus is on identifying and describing critical problems encountered in foaxn tests arid suggesting improvements.Foam applications are classified by the type of gas injected and the type of foam process. This is important since the choice of foamer is process dependent as well as reservoir dependent. The processes evaluated include the use of foam in cyclic steam, steam drive, CO 2 drive, hydrocarbon-gas/nitrogen diversion and in-depth mobility control, GOR-control treatment of production welLs, and water diversion treatment. The reservoir aspect ratio is a useful parameter for comparing foam process varieties and understanding the different application environments.The use of foam in conjunction with steam is a mature and proven technology that, even at current oil prices, cnn be applied in many fields at an attractive cost over that of steam. A key question addressed by this paper is how the positive experience with foam can be successfulty transferred to other gases, for which results are more mixed.Many technical failures are explainable by erroneous problem definition. Either the reservoir cause of the production problem observed was not known, or an in itself viable foam process was applied to the wrong reservoir. In many cases, reservoir description was poor prior to the foam test, and insufficient data were collected during the test to obtain a clear picture of the effects of the foam. Interference from neighboring patterns or welis often cause problems with interpreting the effects of a foam treatment. The presence of fractures may have been the cause of several failed test.s. Only in one case was a treaunent procedure devîsed specifically to account for fractures, with encouraging results. A few early failures appear to have been due to use of thermaily sensitive foainers. In some later tests, the choice of foamer appears less than optimal in view of later, comparable product selection efforts. A few projects were rated as technical successes but economic failures, but the cost of chemicals was generaily not the cause of this problem. Production well treatments, which have been rarely used in the past, show definite possibiliues for the near future. IntroductionThe combination of a gas and a foaming agent injected in a hydrocarbon reservoir can generate a foam. In broad terms, foam can be described as a continuous liquid phase surrounding a discontinuous gas phase. As the liquid network is composed of thin films reducing and sometimes even biocking the gas flow, this process can be applied to improved and enhanced oil recovery. Foam has been used to improve the injection of various gases, as a means of reducing coning and cusping in producers, to improve gas storage and in some cases to enhance waterflooding. Figure 1 illustrates the different problems with gas injection that foam can soive.The practical oilfield experience with foam spans ...

Mobility control during CO2 EOR in fractured carbonates using foam: Laboratory evaluation and numerical simulations

“…Recent research, however, confirms in-situ foam generation in single fractures (Buchgraber et al, 2012;Kovscek et al, 1995), leading to increased sweep (Yan et al, 2006) and flow diversion within a rough-walled carbonate fracture network during co-injection of surfactant and gas . Hence, the reported unsuccessful foam pilots in fractured reservoirs may be related to operational issues or lack of optimized, field-specific surfactants (Castanier and Hanssen, 1995;Prieditis and Paulett, 1992), rather than lack of foam generation mechanisms in fractured reservoirs. With the development of better surfactants (Buchanan, 1998;Cui et al, 2014;Elhag et al, 2014;Ryoo et al, 2003), the injection of foam in naturally fractured reservoirs is increasingly recognized as a potential EOR technique in fractured reservoirs (Farajzadeh et al, 2012;Haugen et al, 2012;Lopera Castro et al, 2009;Panahi, 2004;Pancharoen et al, 2012;Zuta and Fjelde, 2010).…”