Thermo-Kinetic Modeling of Asphaltene Flocculation during Gas Miscible Injection Flow in Shale Oil

近年来，非常规油藏的开发对美国石油产量的快速增长起到了至关重要的作用，从而降低了对外国石油的依赖。虽然非常规油藏可以在水平威尔斯井中使用水力压裂法开采，但采用这种技术的生产通常只能回收4%至6%的可用石油。目前用于解锁剩余石油的注气技术受到注入气体时石油性质发生变化的限制。 这导致被称为沥青质的重质有机固体的沉积，其悬浮在油中。沥青质的沉积最终需要钻更多的威尔斯井，因为它降低了岩石的渗透性，损害了地层，并堵塞了地层孔隙和油管。该项目预计将开发和实验验证一个模型，能够预测的热力学和动力学的沥青质絮凝下注入混溶性气体混合物，扩展过去的研究的基础上连续注气的有前途的新模式的循环注入。这项建模工作预计将有助于开发新的注气工艺，这将提高美国页岩油采收率，减少石油开采所需的能源，并减少钻探新威尔斯井的需求。涉及高中学生和教师的教育活动将提高对石油生产技术的理解。目前的模型没有充分描述页岩油成分、气体成分和压力以及注入时机如何影响沥青质絮凝，而沥青质絮凝是影响石油生产和采收率的关键因素之一。在本研究计划中，两组实验研究将探索页岩油中沥青质的絮凝。首先，批量研究将用于确定二氧化碳和氮气的气体混合物在超出先前研究的温度和压力下的最小溶解性气体压力（MMP）。沥青质胶体颗粒的絮凝动力学分析将使用共聚焦显微镜成像技术进行，絮凝沥青质的尺寸分布作为时间的函数将用于验证新开发的动力学模型。对MMP和胶体颗粒的参数分析将允许量化絮凝动力学。第二，将使用一个流通过滤装置，以量化沥青质的热力学和动力学絮凝性能在循环和连续注气混相注入条件下，扩展和验证模型在批量研究。新开发的热动力学模型将是第一个将沥青质聚集的热力学和动力学描述结合在一个模型中的模型。这些研究工作将产生一种新的、简单的、准确的和通用的数学模型，该模型可用于在油田中注入混相气体时使沥青质沉积最小化，补偿油组成、压力、温度、时间、该奖项反映了NSF的法定使命，并被认为是值得通过使用基金会的智力价值和更广泛的评估支持影响审查标准。

In recent years, the development of unconventional oil reservoirs has played a critical role in the rapid increase of oil production in the United States, thereby decreasing the dependence on foreign oil. Although unconventional oil reservoirs can be tapped using hydraulic fracturing in horizontal wells, production with this technology typically recovers only 4 to 6% of the available oil. Gas injection technologies currently used to unlock the remaining oil are limited by changes that occur in the oil properties when the gas is injected. This leads to deposition of heavy organic solids known as asphaltenes that are suspended in the oil. Deposition of asphaltenes ultimately requires more wells to be drilled, as it reduces rock permeability, damages the formation, and plugs the formation pores and well tubing. This project is expected to develop and experimentally validate a model capable of predicting the thermodynamics and kinetics of asphaltene flocculation under injection of miscible gas mixtures, extending past studies based on continuous gas injection to the promising new mode of cyclic injection. This modeling work is expected to aid in the development of new gas injection processes that will improve U.S. shale oil recovery rates, decrease the energy needed for oil extraction, and reduce the need for drilling new wells. Educational activities involving high-school students and teachers will enhance understanding of oil production technologies.Current models do not fully describe how shale oil composition, gas composition and pressure, and injection timing affect asphaltene flocculation, one of the critical components impacting oil production and recovery efficiency. In this research program, two sets of experimental studies will explore asphaltene flocculation in shale oil. First, batch studies will be used to determine the minimum miscibility gas pressure (MMP) for gas mixtures of carbon dioxide and nitrogen at temperatures and pressures that extend beyond prior studies. The analysis of the flocculation kinetics of asphaltene colloidal particles will be carried out using confocal microscopy imaging techniques and the size distribution of flocculated asphaltene as function of time will be used to validate a newly developed kinetic model. Parametric analysis of the MMP and colloidal particles will allow quantification of flocculation kinetics. Second, a flow-through filtration apparatus will be used to quantify asphaltene thermodynamic and kinetic flocculation properties during cyclic and continuous gas injection under miscible injection conditions, extending and validating models developed during the batch studies. The newly developed thermo-kinetic model will be the first model of its kind that combines thermodynamic and kinetic descriptions of asphaltene aggregation in one model. These research efforts will lead to a new, simple, accurate, and universal mathematical model that can be used to minimize asphaltene deposition upon miscible gas-injection in the field, compensating for variations in oil composition, pressure, temperature, time, and gas injection composition.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.