Quantification of the concentration dependent diffusivity and dispersivity of light hydrocarbons in heavy oil

加拿大西部的油砂占1850亿桶可采石油中的180桶，但含有粘度从1000到100多万厘泊(水为1 CP)的重油和沥青。原地稠油的回收依赖于我们降低原油粘度并将其动员到紧密堆积的砂粒或固结碳酸盐岩的孔隙空间中的能力。在商业上，使用能源和水密集型的热方法，将蒸汽注入一口井，通过热传递降低粘度，将石油动员到生产井并带到地面。一种能耗较低、更可持续的方法是使用轻烃溶剂代替水蒸气，通过传质来降低沥青的粘度。 “重油中轻烃浓度相关扩散系数和分散率的量化”的目的是：1)进一步研究轻烃在重油和沥青中的浓度相关扩散系数；2)在孔隙尺度上定量传质。第一个目标是扩展之前开发的数学模型。(James等人)2010)新模型将纳入非理想溶液的热力学。使用新的模型，我们将进行参数研究，以建立轻烃在重油/沥青中扩散系数的经验关联式。这项工作的新颖性将是开发一种新的经验相关性来取代历史相关性。第二个目标是通过开发一种方法来测量溶剂在重油中的分散度，然后使用分散度和扩散系数来量化孔隙尺度上的传质；我们将计算实验室条件下的弥散系数，并将其与其他找到的(反计算、调谐参数或相关)弥散系数进行比较。对弥散和扩散的独立知识将提供对孔隙尺度物理的洞察，并使在预尺度数学模型中能够更准确地描述该过程。

The oil sands in western Canada account for 180 of the 185 billion barrels of recoverable oil but contain heavy oil and bitumen whose viscosity ranges from 1,000 to over one million centipoises (water is 1 cP). The recovery of the in-situ heavy oil relies on our ability to reduce the oil's viscosity and mobilize it in the pore space of tightly packed sand grains or consolidated carbonate rocks. Commercially, energy and water intensive thermal methods are used where steam is injected into one well, viscosity is reduced by heat transfer, the oil is mobilized to the production well and brought to the surface. A less energy intensive and more sustainable method uses light hydrocarbon solvents instead of steam to reduce the bitumen's viscosity via mass transfer. The goal of the "Quantification of the Concentration Dependent Diffusivity and Dispersivity of Light Hydrocarbons in Heavy Oil" is to 1) further examine the concentration dependent diffusivity of light hydrocarbons in heavy oil and bitumen, and 2) quantify the mass transfer at the pore scale. The first goal is to expand the previously developed mathematical model. (James et al. 2010) The new model will incorporate thermodynamics for non-ideal solutions. Using the new model we will perform a parametric study to develop an empirical correlation for the diffusivity of light hydrocarbons in heavy oil/bitumen. The novelty of this work would be the development of a new empirical correlation to replace historic correlations. The second goal is to quantify the mass transfer at the pore scale by developing a methodology to measure the dispersivity of solvent in heavy oil, then using the dispersivity and the diffusivity; we will calculate the dispersion coefficient for laboratory conditions and compare it to otherwise found (back calculated, tuned parameter or correlation) dispersion coefficients. Separate knowledge of the dispersion and diffusion will provide insight into the pore-scale physics and enable a more accurate physical description of the process in pre scale mathematical models.