Development of Cement Slurry Composition with Self-healing Properties

The construction of oil and gas wells involves well casing and annulus cementing. Cement stone undergoes dynamic loads during drilling, perforation or hydraulic fracturing of a productive formation, and corrosive leaching, exposure to rock pressure and temperature during operation. All this causes fractures and channels to form, through which formation fluids can migrate to upper or lower horizons, as well as to the wellhead. This paper studies a new composition of a cementing material with self-healing properties to control behind-the-casing flow by sealing the annulus and adding a water-swellable polymer (WSP) in a three-layer polyethylene glycol (PEG) shell to the cement slurry. In addition to self-healing of cement stone, the paper also considers an additive to increase the strength characteristics of cement stone with silica, which made it possible to compensate for the loss of stone strength after WSP addition. The findings of the study to determine the strength of cement stone samples, density, spread ability and setting time of cementing slurries with WSP are presented. In addition, a new method for encapsulating polymer particles in a water-soluble shell is presented.