Studies of the Mechanism of Paraffin Deposition and Its Control

Abstract

A review of the background literature on the paraffin deposition problem has shown:it is a major production operational problem,the problem apparently occurs in all crude oil types and areas of production, andinsufficient information is available to clearly delineate its occurrence. A number of experiments have been performed which show that there are numerous types of paraffin deposition. Several evaluation schemes have been devised, one of the most useful is the determination of viscosity at various temperatures. The viscosity temperature curves of several types of crude oils are discussed with reference to the deposition problem. Solvent evaluation procedures have been proven useful in determining the response of a given paraffin to a proposed solvent treatment. Introduction When considering that wax or paraffin problems have been recognized as a major problem from the inception of oil production, it is slightly less than amazing that the literature contains only a handful of references in which the problem is surveyed. The latest thorough examination of the problem by Reistle is now 20 years old. Brown reported on the API survey in 1940, Wright on Southeastern Ohio problems, and Sayre on problems in the Bradford, Pa., field in 1951. These papers have discussed the various developments on the problem from an operational standpoint. There is no evidence in the literature that additional work is being done to define the conditions under which paraffin problems occur and examine critically the various means of alleviation. During the past two years, the authors have gradually accumulated background on these aspects of the paraffin problem. Thc technology has advanced sufficiently that a new appraisal of the problem by the industry would yield profitable results. This paper is presented not so much as a completed investigation, but as a stimulus to encourage others to re-examine the problem. This presentation will cover our appraisal of the problem and several techniques we have found useful.

Wax diffusivity under given thermal gradient: a mathematical model

“…Table 1 In fig. 3 of [8] solubility as a function of temperature is plotted for a crude oil with physical properties similar to oil A of [2], confirming that, in the range of temperature of our experiments, a linear approximation for C s is reasonable. Further if we compute the average slope we obtain a value of b w in the same range as the ones reported in Table 1.…”

Mathematical formulation and numerical modeling of wax deposition in pipelines from enthalpy–porosity approach and irreversible thermodynamics

“…To prevent blockage of pipelines, wax deposits should be removed periodically. Different mechanical, thermal, and chemical techniques can be used for wax removal [1][2][3][4][5].…”

“…There are two main processes that affect the deposition of wax in flowlines: (1) heat transfer, and (2) species flow. The heat transfer is mainly from conduction and convection.…”

Application of Gaussian quadrature method to characterize heavy ends of hydrocarbon fluids for modeling wax precipitation

“…The costs associated with such measures could be reduced significantly if accurate means to predict the wax precipitation region were available. Therefore, it is crucial to develop reliable experimental techniques and/or predictive tools for determining wax equilibria [1][2][3][4][5][6][7][8]. One approach to cope with the deposits which may form in reservoirs, pipelines and production facilities is to predict their occurrence through mathematical (thermodynamical) models to design proper systems preventing their formation as well as dissolving them if already formed.…”