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Novel Polymer Modifications Lead to Next-Generation Pour-Point Depressants

Fig. 2—Examples of PPD polymer solutions based on PSMA-1822 and PSMA-1822/2-tetradecyl octadecanol (70/30) (70% active) in xylene.

Current logistics and pipeline-infrastructure limitations make transportation and production of waxy crude oil challenging, necessitating a step change in the chemistry required to mitigate crude-oil-composition issues. For wax prevention, pour-point depressants (PPDs) or wax inhibitors usually are used. A new approach makes use of a special hydrophobe modification in typical polymer systems that significantly broadens the systems’ applicability.

Introduction

Several wax-control strategies are available in the oil industry. Waxy crude oils are sometimes mixed with a diluent to avoid deposits. The diluent can be a gas condensate, natural-gas liquid, or a lighter crude with a lower wax-­appearance temperature. Other possibilities include heating pipelines and isolations, mechanical removal by pigging and wireline cutters, ultrasonic techniques or magnets, microbial treatments or wax dissolvers, wax inhibitors, PPDs, and dispersions. Many polymer compounds are described as PPDs; the ones most extensively used for crude oils are ethylene-­vinyl-acetate (EVA) copolymers, poly-n-alkyl acrylates, methacrylate copolymers, and styrene-maleic anhydride copolymer esters. PPD polymer systems incorporate into the wax crystal and alter or even disrupt the crystal structures. Polystyrene-maleic anhydride (PSMA) copolymers can be modified easily with alcohols, amines, or other materials, which render them suitable to adjust the PPD performance for crude oil. However, until recently, research has focused on the effect of the polymer additives on the crystal structure of treated waxes in the crude oil and not on the applicability of the PPD itself. The PSMA PPD polymer systems are solids and must be solubilized by suitable solvents in order to be applied under field conditions.

This article, written by Special Publications Editor Adam Wilson, contains highlights of paper SPE 187386, “Next-Generation Pour-Point Depressants Based on Novel Polymer Modifications,” by Sabine Scherf and Albert Boddien, Sasol Germany, prepared for the 2017 SPE Annual Technical Conference and Exhibition, San Antonio, Texas, USA, 9–11 October. The paper has not been peer reviewed.
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Novel Polymer Modifications Lead to Next-Generation Pour-Point Depressants

01 September 2018

Volume: 70 | Issue: 9

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