CAUSES OF CHANNEL FORMATION IN CEMENT STONE AND METHODS OF THEIR ELIMINATION

Abstract

As a result of the annular space depressurization and the formation of fluid-conducting channels at the boundaries of the casing-cement stone, cement stone-formation contact, as well as a system of cracks that arise under the influence of a dynamic load, which can be several times greater than the bending strength of the stone, routes are laid for the migration of formation fluids, including gas griffins or behind-the-casing water circulation. The consequences of inter-casing fluid manifestations are premature wear of the cement lining, a reduction in its trouble-free service, immediate shutdown of the well for repairs, all this entails downtime and suppression of the well operating mode due to changes in time of the pressure gradient in the drainage zone and, although temporarily, but a decrease in oil mobility. Due to the fact, that the specific technology and materials for cementing wells predetermine the irreversibility of the process, which cementing is, in some cases traditional restoration technologies turn out to be useless, ending in the abandonment of the well. The only way to prevent violations of the continuity of the cement lining and restore the tightness of the cement ring without transferring the well to repair is the development and use of a special cementing material that would have self-healing properties, capable of self-activation in the event of depressurization of the well lining.