IMODERN APPROACHES TO ASSESSING THE STRESS-STRAIN STATE OF A CEMENT RING DURING HYDRAULIC FRACTURING

Abstract

The article presents a systematized review of modern approaches to assessing the stress-strain state of the cement ring during hydraulic fracturing (HF). It considers analytical models of the multi-layer cylindrical system "casing-cement-rock", numerical calculations using the finite element method, and experimental studies of the mechanical properties of the cement stone, including its tensile strength, modulus of elasticity, and sensitivity to temperature effects. The key factors affecting the stability of the cement layer have been identified: hydraulic fracturing modes, cyclic loading, temperature fluctuations, the quality of cement adhesion to the casing and rock, and the presence of defects (incomplete contact, porosity, microcracks, and voids). It has been shown that as the internal pressure increases, the maximum tensile circumferential stresses occur at the inner surface of the cement ring, which increases the likelihood of cracking and the formation of migration channels.The paper emphasizes that repeated cycles of pressure and temperature changes contribute to the accumulation of microdamage, a decrease in tensile strength, and an acceleration of cement structure degradation, which is critical for multi-stage hydraulic fracturing. A comprehensive approach to assessing the risk of cement ring failure is proposed, combining analytical, numerical, and statistical methods, including sensitivity analysis and probabilistic assessment. The findings can be used in cementing design, cement composition selection, and hydraulic fracturing regime planning to enhance well reliability and prevent inter-formation flow.