Characterization of the Chemical Properties of Crude Oils To Explain Observed Asphaltene Inhibitor Specificity

Abstract

Abstract Asphaltenes are typically defined by solubility as benzene soluble and pentane or heptane insoluble. The deposition and precipitation of flocculated asphaltenes in the oilfield can severely reduce the permeability of the reservoir, cause formation damage and can also plug-up the wellbore and tubing. Asphaltene inhibitors have been used with success in preventing these precipitation/deposition problems. Based on laboratory and field tests, it was found that asphaltene inhibitor performance is oil specific. We present results obtained by analyzing crude oil from two different geographic regions. The crude oil and asphaltene samples were characterized by a variety of analytical techniques including total acid number (TAN), elemental analysis, and Fourier transform infrared spectroscopy (FT-IR). Electrospray ionization Fourier transform ion cyclotron resonance mass spectrometry (ESI FT-ICR MS) was used to further characterize the two different crudes and their associated asphaltenes. Substantial differences between the relative abundance of heteroatom-containing compound classes were found for the two oils. The relationship between these findings and asphaltene inhibitor performance specificity is discussed. The results from this study provide a greater understanding on how different inhibitors interact with asphaltenes thus enhancing the ability to develop the next generation of asphaltene inhibitors. Introduction Asphaltenes are believed to exist in the oil as a colloidal suspension, and are thought to be stabilized by resins adsorbed on their surface. The asphaltenes are normally in equilibrium at reservoir condition.