Analytical Techniques Unveil the Nature of Waxphaltenes Interactions in Solution and with Carbonates and Sandstones

Abstract

Abstract Several studies have demonstrated the nature of wax and asphaltene interactions and their impact on crude properties, including deposition characteristics. Laboratory and field studies have confirmed organic deposits from offshore oil wells containing asphaltenes and paraffins coprecipitated together to form solid aggregates. These can be described as "Waxphaltenes." This study used different techniques to understand better the properties of waxphaltenes from an offshore operation and how they interact with different rock mineralogy. It was found that mixing crude oil with acetone or methyl ethyl ketone (MEK) is highly efficient in the precipitation and isolation of heavy organics and other polar fractions than the traditional use of pentane or heptane from bulk hydrocarbon fluid. GC, FTIR, NMR, and elemental analysis revealed the composition characteristics of isolated organic solids. ATR-FTIR and AFM-IR methods were used to monitor the deposition of oil and organics on the surface of carbonate and silicate rocks. Water imbibition and solvent wash could remove some of the waxphaltenes dominated deposit from the surface but leave a key monolayer of organics adhered to the surface via hydrogen- or ionic bonding, which act as hydrophobic film. A plausible mechanism of such film formation may include di-or multivalent ions as bridging agents to bind with carboxylate and hydroxyl groups present in organic fractions.