Mechanism Of Inhibition Of Paraffin Deposition In Crude Oil Systems

Abstract

Introduction The accumulation of paraffin wax in petroleum reservoirs and production equipment petroleum reservoirs and production equipment remains a continuous problem and expense in the production of oil. The use of scrapers, production of oil. The use of scrapers, hot-oil treatments and solvents has eased the problem; however, with the advent of extremely problem; however, with the advent of extremely deep production, offshore drilling and ocean floor completions, the application of remedial measures becomes prohibitive economically. As a result, use of chemical additives as paraffin deposition inhibitors is becoming more prevalent. prevalent. Since no one additive has proved universally effective, the selection of an efficient additive for a specific application becomes important, and a better understanding of the mechanism of inhibition is necessary. Patton and Chichakli showed that high molecular weight fractions from crude oil significantly affect paraffin crystal growth and retard or prevent paraffin deposition. Hanke and Birdwell also found these fractions were adsorbed preferentially to a metal surface. Other investigators attributed decreased deposition to modifying the paraffin wax crystals or changing the wetting characteristics of the pipe surface. The purpose of this work was to develop a technique for studying the flow characteristics of crude oil at temperatures below the cloud point, examine the effect of various additives point, examine the effect of various additives on these flow characteristics, and to correlate any change in the flow characteristics with depositional tendency. Hanke discussed thoroughly the ideas presented by several investigators concerning presented by several investigators concerning accumulation of paraffin waxes. Tronov used a micro-moving picture camera to record paraffin deposition in a flowing well and found nucleation of paraffin crystals occurred directly on the metal surface. Paraffin crystals already in suspension were usually deposited in quiescent parts of the equipment. parts of the equipment. Hunt and Jorda consider surface roughness the only factor controlling the amount and characteristics of paraffin deposits However, Jorda also found use of smooth plastic tubing of tetrafluorethylene, polyethylene and polypropylene still resulted in massive polypropylene still resulted in massive deposits. Patton found that the presence of an adsorbed crude film on a steel surface increased the surface energy of the metal and caused greater deposition. The association of asphaltenes and paraffin wax in wax deposits has been mentioned paraffin wax in wax deposits has been mentioned by several investigators, and Preckshot found that bitumen deposits possibly were associated with an electro-depositional effect.