Economics of Field Proven Chemical Flooding Technologies

Abstract

Chemical enhanced oil recovery technologies are field-proven methods that improve overall oil recovery. High oil prices and dropping reserves replacement has stimulated interest in these technologies, particularly for application in mature waterfloods. Depending upon the perspective of investors, the decision to proceed with an oil field project may depend upon projected: Rate of Return, Return on Investment, $/bbl of added reserves, cumulative cash flow, or combinations of these. This paper discusses chemical flooding processes, constraints on application, and presents economic impacts of: injected chemical cost, oil price, chemical concentration, oil recovery, and process time. The alkaline-surfactant-polymer technology is compared with micellar flooding and alkaline-polymer flooding. For example, a typical range of chemical costs per barrel of added oil for an Alkaline-Surfactant-Polymer project would be $3.50/bbl to $12/bbl for oil recoveries ranging from 0.2 PV down to 0.05 PV (or approximately 25% OOIP to 6.25% OOIP). Rate of Return (ROR) and payout time depends upon process rate, or pore volume per year of injection. Chemical flooding places the majority of cost over the first 50% pore volume of injection whereas, oil incremental income is delayed until the developing oil bank reaches production wells. In today's oil price environment of >$40/bbl, chemical flooding technology provides significant financial returns with increased ultimate oil recoveries. Introduction Chemical enhanced recovery processes are by any measure quite mature. L. C. Uren and E.H.Fahmy wrote in 1927 "A definite relationship exists between interfacial tension of the oil against the flooding medium and the percentage recovery obtained by flooding." A patent was issued the same year to H. Atkinson for the use of aqueous soap solutions or other aqueous solution to decrease the "surface tension" between oil and flooding medium. Pennsylvania State University reported much of the research on surfactant over the next 25 years. A tremendous amount of research on interactions of various aqueous chemicals with oils and rock has been performed since that time. Of particular relevance to this paper are the work of Reisberg and Doscher in 1956 using alkalis and alkali-surfactants, the "soluble oil" process of Holm and Bernard and Csazar, and Gogarty and Olson's micellar process known as Maraflood.Ô All of the major oil company research groups became keenly interested in recovering additional resource from mature waterfloods during the Arab oil embargo of 1973 and the ensuing run up of oil price. Gogarty speculated that petroleum sulfonate manufacturing capacity in the early 1970's of on the order of 388 million pounds would be insufficient to meet the demand for prospective projects that, at the time, were estimated with potential to produce 25 to 60 billion bbl of oil. This possibility and the desire to further improve economics of the process lead Marathon to constructing a 5,000 bbl/day crude-oil sulfonate slug manufacturing facility. Gogarty concluded that the economics of surfactant flooding were driven by factors influencing project life (well spacing, permeability, thickness, depth, etc.), costs (injected fluid costs, surface facilities, additional wells, etc.), royalty and taxes, and most significantly, the price of oil. This remains unchanged, though oil prices have risen considerably above the $11/bbl to $15.50/bbl considered in the economics of the time. Chemical Flooding Processes Many chemical flooding processes have been used to enhance oil recovery efficiency and effectiveness. This paper will discuss only those process recognized to reduce waterflood residual oil saturation, which we categorize as:Micellar-Polymer (MP)Surfactant-Polymer (SP)Alkaline-Polymer (AP)Alkaline-Surfactant-Polymer (ASP)

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