Effects of Waxes and the Related Chemicals on Asphaltene Aggregation and Deposition Phenomena: Experimental and Modeling Studies

Abstract

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.

Experimental Measurement and Equilibrium Modeling of Adsorption of Asphaltenes from Various Origins onto the Magnetite Surface under Static and Dynamic Conditions

“…The adsorption and deposition of asphaltene on the surface of reservoir rocks can eventually lead to oil production decline. 1,3,4 Coating of the rock surface by polar molecules such as asphaltene or even resin is often cited as the main reason for the wettability alteration of reservoir rocks. 5 Hence, the study of adsorption of asphaltenes onto the surface of reservoir rocks and solid−fluid interaction with rock minerals is very important to gain insight into the better management of oil production in formations.…”

“…Because of its different functional groups and high polarity, asphaltene can cause many problems such as wettability alterations, plugging of rock pores, and permeability reduction of reservoir rocks in the oil reservoir. The adsorption and deposition of asphaltene on the surface of reservoir rocks can eventually lead to oil production decline. ,, Coating of the rock surface by polar molecules such as asphaltene or even resin is often cited as the main reason for the wettability alteration of reservoir rocks . Hence, the study of adsorption of asphaltenes onto the surface of reservoir rocks and solid–fluid interaction with rock minerals is very important to gain insight into the better management of oil production in formations. , However, the lack of definite information about asphaltene interactions with different rock mineralogy and its behavior in different fluid environments due to the complexity of the asphaltene molecule has made this topic an attractive area for research.…”

Wax Deposition Law under a Gas–Liquid Bubbly Flow Pattern

“… 1 − 5 If the deposits are not removed in time, it may even threaten the safety of transmission in serious cases. 6 − 9 Wax deposition has always been a hot issue in the field of petroleum exploration and the development and pipeline transportation. Detailed research has been conducted on it by scholars for many years.…”

Investigating the Performance of Carboxylate-Alumoxane Nanoparticles as a Novel Chemically Functionalized Inhibitor on Asphaltene Precipitation

“…To investigate the practical approaches for preventing or postponing the asphaltene precipitation, many researchers endeavor to find practical, cost-effective, and environmentally benign solutions to overcome the asphaltene deposition problems. − Hu et al investigated the effect of the ionic liquids based on [Cnpy] + and [C 4 iql] + cations and the alkylbenzene-derived amphiphiles Cnphol, Cnbsa, and CnbsNa on the asphaltene precipitation. Their proposed mechanism illustrated that due to having high-charge-density anions, ionic liquids could act as effective inhibitors via the destruction of asphaltene associations.…”