Solubility Studies on High Molecular Weight Paraffin Hydrocarbons Obtained From Petroleum Rod Waxes

Abstract

Published in Petroleum Transactions, AIME, Volume 204, 1955, pages 151–155. Abstract Data are presented on the physical properties of five waxes obtained from fields in Texas and Louisiana in which "paraffin" troubles are being experienced. The crude paraffin was fractionated into three components, soluble in cold acetone, soluble in boiling acetone, and insoluble in boiling acetone. The acetone insoluble fraction was found to consist essentially of straight chain paraffin hydrocarbons in the molecular weight range 525 to 700. Solubilities of the purified high molecular weight paraffins were determined in a number of solvents. It was found that in hydrocarbon solvents, including crude oil, solubilities could be calculated satisfactorily by use of ideal solubility relations. In chlorinated, and oxygenated solvents, large deviations from ideal behavior were observed. These deviations could be partially correlated with the internal pressure of the solvent. Introduction A problem encountered in many producing oil fields is that of "paraffin" deposition. The problem refers to the deposition of material from the crude oil onto tubing, pumping rods, flow lines, or other material contacted by the crude. This problem has been recognized for nearly a hundred years, and numerous investigations have been reported on its causes and prevention or alleviation. One of the more comprehensive of such investigations was published by Reistle in 1932. A few of the salient findings of his report are briefly as follows: The term "paraffin" as used to describe this problem refers to the deposit of carbonaceous material which is not soluble or dispersible by the crude oil under the conditions where deposition occurs. The "paraffin" normally consists of high molecular weight paraffin hydrocarbons, both straight chain and branched, resins and asphaltic materials of undetermined nature, occluded oil and water, and possibly sand. In consistency, the deposit may vary from a soft, sticky material, to one which is hard and brittle. Deposits are usually black, although lighter colors are sometimes observed.