APPROACH TO DETERMINING THE ABILITY OF TUBING COATINGS TO RESIST AFS DEPOSITS

One of the common types of complications in the operation of oil production wells, especially in the development of fields with heavy oil, is the formation of asphalt-tar-paraffin deposits (AFS) on the inner surface of tubing. The formation of AFS leads to a decrease in the internal cross-section of the tubing, a decrease in production, an increase in electricity costs for lifting the product and requires the well to be stopped for cleaning measures. There are several known and widely used technologies to prevent the formation of deposits, as well as methods for their removal. Field development conditions and characteristics of the produced product are diverse and often require an individual approach or the development of new technologies. Many modern methods of combating the formation of AFS only increase the overhaul period of wells for some time, and it is not always possible to completely avoid the formation of deposits. It is necessary to know the composition of deposits, their physicochemical properties and causes of formation. Attention should also be paid to the correct selection of methods that will achieve the greatest efficiency under different operating conditions, and will also be economically feasible.An effective way to prevent AFS in pipes is to use tubing with an internal coating. These coatings, due to low roughness and oleophobia, reduce the intensity of the formation of AFS deposits on the walls of the tubing or completely eliminate it. On the domestic market there are brands of coatings of various manufacturers, differing in production technology and operational characteristics. At the same time, in the regulatory documentation there are no requirements for the characteristics of coatings and methods for testing them for the ability to reduce and prevent AFS. Evaluation of the applicability of tubing coating and its effectiveness is carried out by conducting pilot tests (OPI) of tubing on the existing well stock with AFS complications.The article describes the approach to laboratory evaluation of the ability of the inner coating of tubing to prevent the formation of AFS, as well as the possibility of using one or another coating in the conditions of Rosneft fields, taking into account the physicochemical properties of the hydrocarbons produced. This approach makes it possible to reduce the time of introduction of new protective coatings into production processes due to the rejection of long-term OLP in favor of laboratory tests.