Reservoir Simulation Study of Water-in-Oil Solubility Effect on Oil Recovery in Steam Injection Process
- Shanqiang Luo (Schlumberger) | Maria A. Barrufet (Texas A&M U.)
- Document ID
- Society of Petroleum Engineers
- SPE Reservoir Evaluation & Engineering
- Publication Date
- December 2005
- Document Type
- Journal Paper
- 528 - 533
- 2005. Society of Petroleum Engineers
- 5.5 Reservoir Simulation, 5.5.1 Simulator Development, 5.4.6 Thermal Methods, 4.3.1 Hydrates, 4.1.1 Process Simulation, 5.8.3 Coal Seam Gas, 5.8.2 Shale Gas
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Water is usually considered insoluble in the oil phase; however, at thetemperatures typically encountered in the steam-injection process, water mayhave higher than 40 mol% solubility in the oil phase. On a mass basis,experimental results from the literature indicate water solubility as high as33%. We developed a practical and robust algorithm for a water/oil/gasthree-phase flash calculation. The algorithm is based on the well-developedvapor/liquid two-phase flash-calculation algorithm and avoids trivial or falsesolutions commonly found in multiphase flash calculations. We also developed afully compositional thermal reservoir simulator, considering water/oil mutualsolubility, to study the effect of water-in-oil solubility on oil recovery inthe steam-injection process. A simulation study shows that when water issoluble in the oil phase, it may increase oil recovery appreciably. We alsofound that the oil fluids should be characterized with at least threecomponents for accurate compositional thermal reservoir-simulation study.
Steam injection is used widely as an improved-oil-recovery method for theproduction of heavy oil and many light-oil resources. Conventional reservoirsimulation of the steam-injection process simplifies the computations byignoring water solubility in the oil phase. However, as temperature increases,water solubility in the oil phase increases significantly. Griswold and Kaschstudied water/oil mutual solubilities at elevated temperatures. Their data showthat for a 54.3°API naphtha, the solubility of water in oil is 16.18 mol% at431.6°F; for a 42°API kerosene, the solubility of water in oil is 34.97 mol% at507.2°F; and for a 29.3°API lube oil, the solubility of water in oil is 43.44mol% at 537.8°F. Nelson also showed that water solubility in oil is as high as42 mol% at 540°F. Heidman et al. showed that the solubility of water in liquidC8 is 38.7 mol% at 500°F. Glandt and Chapman obtained up to 33.3 wt% of waterdissolved in crude-oil mixtures and analyzed its effect on oil viscosity. Thishigh solubility will dramatically change the viscosity, density, and thermalexpansion of the hydrocarbon phase and, consequently, affect the productionperformance. Therefore, a rigorous and efficient multiphase flash algorithm isneeded to evaluate the phase equilibrium of water/hydrocarbon systems. Also,fully compositional thermal reservoir simulations, which consider water-in-oilsolubility, are necessary to evaluate the extent to which the water-in-oilsolubility affects oil recovery in the steam-injection process.
|File Size||783 KB||Number of Pages||6|
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