Modelling of Non-Equilibrium Heavy Oil-Solvent Behaviour
提出了一个多组分动力学模型来模拟稠油本体环境中非平衡溶剂出溶和反溶过程。该模型由微气泡组成，微气泡继承了溶液气体的物理特性，并被视为类气体液体，以模拟体积膨胀过程中的泡沫油行为。自由气体被认为能够直接转移到溶液气体中，以模拟体积压力增加时溶解过程中发生的滞后现象。动力学模型包括三个具有七个参数的伪化学反应，这些参数是根据实验数据校准的。该模型通过热储层模拟器进行了验证，结果能够准确预测两种不同溶剂稠油系统在15°C和75°C下不同压力变化率下的油气系统体积变化。对四个反应级数和三个反应频率因子进行了调整，结果表明，在溶剂为CH4或C2H6的溶剂-重油体系中：（1）在溶剂浓度相似的重油的压力消耗过程中，溶剂为C2H6而不是CH4存在更强的泡沫油行为；（2） 对于这两种溶剂，在较高的温度下，微气泡的释放速率较大，并且无论温度如何，微气泡释放速率都倾向于随着压力的下降而增加；和（3）在溶剂溶解过程中，对于CH4和C2H6，相对较高的压力和温度都是促进溶剂溶解回重油的重要因素。
A multi-component kinetic model is proposed to simulate non-equilibrium solvent exsolution and back dissolution processes in the heavy oil bulk environment. The model consists of micro bubbles, which inherit physical properties from the solution gas and is treated as a gas-like liquid, to simulate foamy oil behavior during volume expansion processes. Free gas is considered as being able to transfer directly to solution gas to simulate the hysteresis which happens in the dissolution process when volume pressure increases. The kinetic model comprises three pseudo-chemical reactions with seven parameters which were calibrated against experimental data. The model was validated by using a thermal reservoir simulator and the results were capable of predicting the oil-gas system volume changes for two different solvent-heavy oil systems accurately under various pressure variation rates at both 15 and 75°C. Four reaction orders and three reaction frequency factors were tuned and it indicated that in a solvent-heavy oil system with solvent CH4 or C2H6: (1) stronger foamy oil behavior exists with solvent of C2H6 instead of CH4 during pressure depletion processes for heavy oil with the similar solvent concentration; (2) for both solvents, micro bubble release rates are larger at higher temperature and the rates tend to increase with pressure decline regardless of temperature; and (3) in the solvent dissolution process, for both CH4 and C2H6, relatively high pressure and temperature are both significant elements for promoting solvent dissolution back into heavy oil.
Effect of temperature on viscosity of Athabasca bitumen (Mehrotra andSvrcek, 1986).
