Mohammadpour Milad, Malayeri M Reza, Kazemzadeh Yousef, Riazi Masoud
Enhanced Oil Recovery Research Center, School of Chemical and Petroleum Engineering, Shiraz University, Shiraz, Iran.
Department of Chemical Engineering, School of Chemical and Petroleum Engineering, Shiraz University, Shiraz, Iran.
Sci Rep. 2023 Sep 21;13(1):15727. doi: 10.1038/s41598-023-42886-5.
Asphaltene instability in oil causes severe problems such as deposition and more stable emulsions. Formation and stability of W/O emulsions based on location in which they are formed can either be helpful or detrimental for enhanced oil recovery. Changes in oil composition (saturate, aromatic, resin, and asphaltene) can also render the stability of asphaltene. In this study, the formation and staility of emulsions are investigated using changes in the colloidal instability index (CII) at ambient and reservoir conditions. Experiments were conducted for crude oil samples from various reservoirs which showed that when CII is greater than 1.059, due to the excessive instability of asphaltene and its movement toward the water-oil interface, the formed emulsion would be more stable. When CII was below 1.059 though, the asphaltene became stable hence did not tend to be placed at the water-oil interface, thus less stable emulsion was expected. Higher pressures led to an increase in the stability of the emulsion. These changes in the process of emulsion stability are related to two mechanisms of asphaltene absorption and greater shear stresses.
原油中的沥青质不稳定会引发诸如沉积和形成更稳定乳液等严重问题。基于其形成位置的水包油乳液的形成和稳定性，对于提高采收率可能有利也可能有害。原油成分（饱和烃、芳烃、树脂和沥青质）的变化也会影响沥青质的稳定性。在本研究中，利用在环境条件和油藏条件下胶体不稳定指数（CII）的变化来研究乳液的形成和稳定性。对来自不同油藏的原油样品进行了实验，结果表明，当CII大于1.059时，由于沥青质过度不稳定并向油水界面移动，形成的乳液会更稳定。然而，当CII低于1.059时，沥青质变得稳定，因此不会倾向于聚集在油水界面，从而预期乳液稳定性较低。较高的压力会导致乳液稳定性增加。乳液稳定性过程中的这些变化与沥青质吸附和更大剪切应力这两种机制有关。
