Waxy gels with asphaltenes 1 - Characterization of precipitation, gelation, network strength and morphology

Oil pipeline blockages by paraffinic deposits remain a major problem in the oil industry today. Among the strategies to combat wax gelation is the use of polymer additives. Another component in crude oil that is involved with such deposits is the asphaltene fraction. A model with 3-10 wt % multi-component wax containing 85 wt % n-paraffins ranging from C₂₀ to C₄₈ was evaluated with 0-0.2 wt % asphaltenes. The gelation temperature and yield strength of the gel were examined. Addition of asphaltenes depressed the precipitation and gelation temperatures. At high asphaltene concentration and/or low wax concentration, addition of asphaltenes significantly reduced crystal size and yield stress, much like a polymer additive for wax inhibition. However, when both asphaltene concentrations were low (≤ 0.1 wt %) and when wax concentration was high, there was little effect on microstructure. In such cases, the yield stress was unaffected or even greater than the waxy sample with no asphaltenes. This is an abstract of a paper presented at the AIChE Annual Meeting (Salt Lake, UT 11/4-9/2007).