ABOUT REQUIREMENTS TO PLUGGING MATERIALS AND TO TUBING TECHNOLOGY FOR THE CASING COLUMNS WORKING IN EXTREME CONDITIONS

Abstract

The most vulnerable elements of the well lining is cement paste in injection wells and the lower parts of the intermediate and surface casings, which suggests the need for the study of additional requirements to plugging materials and lining technology of the specified lining elements. Analysis shows that the main number of workover happens for the share of injection wells, and the number of detected violations in injection wells which is more than an order of magnitude exceeds the corresponding figures for the production casing. Samples of cement stone, selected from the injection and production wells showed that in injection wells, the cement stone collapses in 4-5 years.The mechanism and kinetic process of destruction of cement stone under the influence of leaching was considered and the ways of increasing the durability of linings in injection wells were shown. Leaching corrosion processes in injection wells strengthens during the formation of cracks in the cement stone as a result of technological operation inside the casing string. The most dangerous technological operations are; perforation and deepening of the well. In order to obtain high-quality well anchoring, it is inevitable to regulate the basic properties of cement mortars with the help of various chemical reagents. At the same time, the filtration characteristics (water output and water separation), setting time, pumpability, rheological parameters, as well as the properties of the resulting stone require correction most often in grouting solutions It is shown that for plugging materials, the most preferred way to increase the resistance of grouting stone to dynamic loads is dispersed reinforcement, which can be effectively regulated by the most important characteristics of cement slurries and cement stone can be obtained from them. Studies have been conducted on the influence of basalt fiber and polyamide fiber on the basic physical and mechanical properties of the resulting stone, such as the strength of cement stone, deformation of cement stone during destruction, the specific impact strength of Portland cement stone, as well as the permeability of cement stone. Studies have shown positive results of the addition of basalt fiber at concentrations up to 2%.