Joonaki Edris, Hassanpouryouzband Aliakbar, Burgass Rod, Hase Alfred, Tohidi Bahman
Centre for Flow Assurance Research Studies (CFAR), Institute of GeoEnergy Engineering, School of Energy, Geoscience, Infrastructure and Society, Heriot-Watt University, Riccarton, Edinburgh EH14 4AS, U.K.
TÜV SÜD National Engineering Laboratory, Scottish Enterprise Technology Park, East Kilbride, South Lanarkshire G75 0QF, U.K.
ACS Omega. 2020 Mar 23;5(13):7124-7134. doi: 10.1021/acsomega.9b03460. eCollection 2020 Apr 7.
Solid deposition during production, transport, and storage of crude oils leads to significant technical problems and economic losses for the oil and gas industry. The thermodynamic equilibrium between high-molecular-weight components of crude oil, such as asphaltenes, resins, and waxes, is an important parameter for the stability of crude oil. Once the equilibrium is disturbed due to variations in temperature, pressure, and oil composition during production, the solubility of high-molecular-weight waxes decreases. This results in a decrease in the wax appearance temperature (WAT) and the deposit of wax onto solid surfaces. On the other hand, under these conditions, asphaltenes do not interact sufficiently with the resins/waxes and tend to flocculate among themselves and form asphaltene nanoaggregates. The role of waxes during the asphaltene aggregation and deposition has not been appropriately explained yet. The objective of this research study is to describe the interaction of asphaltenes and waxes and subsequently address the specific example of an asphaltenic oil commingled with a wax inhibitor-containing oil during the combination of different oil streams. It is a crucial building block for the development of a suitable and cost-effective strategy for the handling of wax/asphaltene associated flow assurance problems. In this work, the quartz crystal microbalance (QCM) technique has been used for the first time to investigate the effect of waxes and related chemicals, which are used to mitigate wax deposition, on asphaltene aggregation and deposition phenomena. Asphaltene onset point and asphaltene deposition rate have been monitored using QCM at high pressure-high temperature (HPHT) conditions. This study confirms that the different wax inhibitor chemistries result in significant differences in the pour point decrease and viscosity profiles in crude oil. Different wax inhibitors also showed different outcomes regarding the asphaltene deposition tendency. A comprehensive modeling study has also been conducted for mechanistic investigation of experimental results. In this regard, the perturbed chain statistical associating fluid theory equation of state (PC-SAFT EoS) was utilized to model the systems.
原油在生产、运输和储存过程中的固体沉积给石油和天然气行业带来了重大技术问题和经济损失。原油中高分子量组分（如沥青质、树脂和蜡）之间的热力学平衡是原油稳定性的一个重要参数。一旦在生产过程中由于温度、压力和油成分的变化而使平衡受到干扰，高分子量蜡的溶解度就会降低。这导致蜡出现温度（WAT）下降，并使蜡沉积在固体表面。另一方面，在这些条件下，沥青质与树脂/蜡之间的相互作用不足，倾向于自身絮凝并形成沥青质纳米聚集体。蜡在沥青质聚集和沉积过程中的作用尚未得到恰当解释。本研究的目的是描述沥青质与蜡之间的相互作用，并随后探讨在不同油流混合过程中，含沥青质的油与含蜡抑制剂的油混合的具体实例。这是制定合适且具有成本效益的策略以解决蜡/沥青质相关流动保障问题的关键组成部分。在这项工作中，首次使用石英晶体微天平（QCM）技术来研究蜡和用于减轻蜡沉积的相关化学品对沥青质聚集和沉积现象的影响。在高压高温（HPHT）条件下，使用QCM监测沥青质起始点和沥青质沉积速率。本研究证实，不同的蜡抑制剂化学组成导致原油倾点降低和粘度曲线存在显著差异。不同的蜡抑制剂在沥青质沉积倾向方面也表现出不同的结果。还进行了一项全面的建模研究，以对实验结果进行机理研究。在这方面，采用了扰动链统计缔合流体理论状态方程（PC - SAFT EoS）对系统进行建模。
