PEPTIZATION AND COAGULATION OF ASPHALTENES IN APOLAR MEDIA USING OIL-SOLUBLE POLYMERS

The asphaltene fraction of crude oil contains a variety of acidic and basic functional groups. During oil production and transportation, cha nges in temperature, pressure or oil composition can cause asphaltenes to precipitate out crude oil through the flocculation among these pol ar functional groups. In this study, two types of oil-soluble polymers ? dodecylphenolic resin and poly (octadecene maleic anhydride), were s ynthesized and used to prevent asphaltenes from flocculating in heptan e media through the acid-base interactions with asphaltenes. The exper imental results indicate that these polymers can associate with asphal tenes to either inhibit or delay the growth of asphaltene aggregates i n alkane media. However, multiple polar groups on a polymer molecule m ake ii possible to associate with more than one asphaltene molecule, r esulting in the hetero-coagulation between asphaltenes and polymers. I t was found that the size of the asphaltene-polymer aggregates was str ongly affected by the polymer-to-asphaltene weight (or number) ratio. At low polymer-to-asphaltene weight ratios, asphaltenes keep flocculat ing with themselves and with polymers until the flocs precipitate out of solution. On the other hand, at high polymer-to-asphaltene weight r atios, asphaltene-polymer aggregates peptized by the extra polymer mol ecules can remain fairly stable in the solution.