Lightweight Cement Pastes with Hollow Glass Microspheres: Homogenization of Elastic Parameters and Nonlocal Mechanical Damage Model

Abstract

Hollow glass microspheres (HGMS) are used to lighten cement pastes applied in hydrocarbon extraction and CO2 injection wells. These pastes ensure zonal isolation, protect the casing, and sustain mechanical loads. The use of HGMS lowers density and hydrostatic pressure on the formation, which is crucial in low-strength, deep wells. However, HGMS alter the composite behavior. This work implements a chemo-poromechanical numerical model able to simulate traditional cement pastes under CO2 injection conditions. The model is enhanced to account for HGMS effects on elastic parameters through micromechanical homogenization and includes a nonlocal gradientdependent damage formulation describing stiffness degradation beyond a specified threshold. The coupled model is calibrated and validated using laboratory results.