An optimization study for a steam-foam drive process in the Provost Upper Mannville B Pool (Bodo Reservoir) located in east central Alberta, Canada was conducted using the ARC (AIberta Research Council) foam transport model. The optimization was done with respect to the foam injection strategy and the concentration of the foaming agent (surfactant). A "discounted net profit due" to foam injection was maximized.
Within the scope of this study, oil recoveries of all steam-foam processes investigated were better than the steam-only baseline process. However, not all foam processes were economically viable, optimal processes were dependent on the heavy oil prices. Over a range of heavy oil prices of US$10 to US$20/bbl. the single foam slug process with a total foam injection period of 2 to 3 months and a surfactant concentration of 0.5 to 1% by wt. in the liquid phase of the injected fluids appeared to be the most profitable.
The process of adding foaming agent (surfactant) aqueous solution to the injected steam to form foam in situ has been recognized as a promising technique in recovering heavy oil from underground reservoirs. Foam is well known as a selective blocking agent which can optimize reservoir conformance and minimize steam channelling and gravity override. This paper will demonstrate the necessity of choosing a suitable foam injection strategy for steam-foam drive field applications.
Using the foam transport model developed at Alberta Research Council by Law et al. 1,2 an optimization study for a steam-foam drive process in the Provost Upper Mannville B Pool (Bodo Reservoir) located in east central Alberta, Canada is conducted. In the optimization study it is impossible to examine all of the operation variables. The objective of this study is to investigate the advantage of using a steam-foam drive process instead of a steam-only drive process. The search for an optimal steam-foam drive process is made by permuting operation variables such as foam injection schedule (single or multiple foam slug process), total length of the foam injection period and surfactant concentration. Operation variables such as steam injection rate and steam quality are kept constant. Optimization of the steam-foam drive process is performed by maximizing a "discounted net profit" due to surfactant inject ion.
Detailed descriptions of the ARC foam transport model have been given by Law et al. 1,2. Only a very brief review of this model will be given in this paper.
The foam transport model which is based on the physical properties of an alkylaryl sulfonate surfactant (SUN TECH IV), is a fully implicit multi component thermal reservoirs model having the ability to handle five components and there phases. The five components are water, heavy oil. Surfactant and two additives (non-condensible gases or volatile hydrocarbon components). The three phases are the acqueous water phase, the oild phase and the gaseous phase. Conservation of mass of all components is governed by Darcy's law and is solved implicitly together with conservation of energy.