Master of Science in Petroleum Engineering (MSPE)
A numerous laboratory and field tests revealed that foam can effectively control gas mobility, improve sweep efficiency, and increase oil production, if correctly designed. It is believed that there is a significant gap between small laboratory-scale experiments and large field-scale tests because of two main reasons: (i) typical laboratory flow tests are conducted in linear systems, while field-scale foam EOR processes are performed in radial (or spherical partly) systems in general; and (ii) through the complicated in-situ lamella creation and coalescence mechanisms and non-Newtonian behavior, foam rheology is thought to depend on geometry and dimensionality and, as a result, it is often not clear how to translate laboratory-measured data to field-scale applications. Therefore, this study for the first time investigates how foam rheological properties change in different dimensions and geometries and how such dimensionality-dependent properties are affected by different foam flowing conditions by using mechanistic foam fractional flow analysis. Complex foam characteristics such as three foam states (weak-foam, strong-foam, and intermediate state; sometimes referred to as foam catastrophe theory) and two steady-state strong-foam regimes (high-quality regime and low-quality regime) lie in the heart of this analysis. The calculation results from a small radial or spherical system showed that (i) for strong foams in the low-quality regime injected, foam mobility decreased (or mobility reduction factor increased) significantly with distance which improved sweep efficiency; (ii) for strong foams in the high-quality regime, the situation became more complicated – near the well foam mobility decreased, but away from the well foam mobility increased with distance, which eventually gave lower sweep efficiency; and (iii) for weak foams injected, foam mobility increased with distance which lowered sweep efficiency. The results also implied that the use of fixed value of mobility reduction factor, which is common practice in reservoir simulations, might lead to a significant error, especially for strong foams in the low-quality regime. When the method was applied to the large field-scale applications, it was first shown why strong foams would eventually turn into weak foams. Then additional results showed that strong foams could propagate deeper into the reservoir at higher injection rate, higher injection pressure, and at lower injection foam quality. Foam propagation distance was very sensitive to these injection conditions for foams in the high-quality regime, but much less sensitive for foams in the low-quality regime. This study uses a mechanistic foam model similar to Afsharpoor et al. (2010) which is an updated version of Kam and Rossen (2003), Kam et al. (2007), and Kam (2008). In all calculations, gas and liquid phases are assumed to be incompressible and the presence of oil is not considered at this stage.
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Lee, Woochan, "Investigation of Dimensionality-Dependent Foam Rheological Properties by Using Mechanistic Foam Model" (2014). LSU Master's Theses. 3609.