Controlling Asphaltene Deposition in Oil Wells

Abstract

Summary The deposition of asphaltenes in oil producing formations and production systems has caused problems for years. Selection of chemical control agents in the past has been limited to bulk dissolution studies on samples retrieved from production systems. Until recently, the accepted way to treat these problems has been through the use of xylene, toluene or other aromatic solvents. This method requires the use of large amounts of these solvents, as well as a high frequency of treatment. This paper describes the results of field testing and application of asphaltene control chemicals, and the use of laboratory tests to select asphaltene deposition removal and prevention chemicals. Preliminary dispersant and solvency tests are conducted by an asphaltene dispersant test in hexane. Chemicals which provide promising results in dissolving and dispersing asphaltenes in the non-solvent medium of hexane are selected as candidates for field application, or for additional testing in a core flow deposition removal test. The core flow test apparatus provides a method to introduce asphaltene fouling into a core and study its removal by the use of chemical agents. Using core samples and asphaltenes from the production resource under consideration allows the selection of the best removal chemical.