Polymeric Surfaces for Heavy Oil Pipelines To Inhibit Wax Deposition:  PP, EVA28, and HDPE

Abstract

Pipelines for heavy crude oils have recurrent clogging situations due to paraffin deposition that may lower production rates and be responsible for leakages. This work evaluates the effect of three polymers on crude oil wettability and on paraffin deposition inhibition: polypropylene (PP), high-density polyethylene (HDPE), and a vinyl acetate copolymer with 28% oxygen content (EVA28). Under static conditions, the interfacial tension between the crude oil and the linings was determined by the contact angle being 12% and 17% higher for EVA28 and HDPE, respectively, than for that of PP. As the crude oil inside the pipelines is flowing at high rates, the dynamic interfacial tension was also observed for high flow rates when molecular effects overtake hydrodynamic ones. For this, the perturbation of intermolecular orientation within the flow, caused by the beginning of deposit formation and by the wettability, was determined using depolarization of the fluorescence induced by laser. Under flow, EVA28 and HDPE caused an increase of interaction with the crude oil of 79% and 43%, respectively, compared to that of PP. HDPE yielded globular wax deposits. The higher tendency of HDPE than PP to form deposits was attributed to the absence of methyl branches in the first. The EVA28 tendency to form deposits was attributed to the oxygen atoms on the surface as well as to its high polycyclic aromatic hydrocarbon sorption. Thus, under a high flow rate, PP is better suited to inhibit wax deposition than HDPE and EVA28.

Multifunctional anti-wax coatings for paraffin control in oil pipelines

“…In order to meet the actual working conditions in crude oil transportation, Quintella et al evaluated the influence of the flow state of crude oil on the inhibition of paraffin deposition when using three types of polymer coatings (Quintella et al 2006). Figure 1 shows the structures of three coatings: polypropylene (PP), high-density polyethylene (HDPE) and ethylene vinyl acetate copolymer (EVA28) with an oxygen content of 28%.…”

Design of surfaces for controlling hard and soft fouling

“…Many early studies demonstrate surface energy and roughness as co-dependent factors in paraffin adhesion [168,172,173]. Quintella et al [174] showed the dependence of wax deposition on the contact angle of a surface with paraffin oil. They observed high wax deposition rates for vinyl acetate copolymers with 28% oxygen content (EVA28) when compared with the more hydrophobic polymers, polypropylene (PP) and high-density polyethylene.…”

Effects of paraffin chain size on the oil outflow investigated by a combination of thermal lens and laser-induced fluorescence spectrometries

“…The laser beam is modulated by a chopper at a frequency of 10 Hz, and the signal magnitude is experimentally determined by a lock-in that sends the information to a dataacquisition interface. In this work the sample has not only a single known chromophore and the intrinsic fluorescence is being detected due to several chemical species of oil which are usually polycyclic aromatic hydrocarbons [31]. Thus, there's not a single a, since the signal registered by the detection system is the result of contributions of different chemical species, with specific electronic structures.…”