Mechanical Performance of One Latex Cement System for Thermal Storage Wells

To minimize heat losses in the high temperature thermal storage wells, Brookhaven National Lab introduced one type of hydrophobic lightweight thermally insulating cement with a thermal conductivity three times lower than that of regular cement. However, the repeated thermal shock conditions that are the major concern for well integrity can be especially difficult for lightweight cements. This study provides an in-depth evaluation of the latex cement's mechanical performance under in situ conditions, including pressures up to 10 MPa and temperature as high as 200 °C. Before being subjected to thermal shock, the cement showed an elastic modulus ranging from 0.3 to 1.9 GPa, a Poisson ratio between 0.05 to 0.19, and a strength between 4.7 and 27.5 MPa. However, after thermal shock, there is a noticeable increase in its mechanical properties: the elastic modulus spans from 1.6 to 3.7 GPa, the Poisson ratio becomes 0.12 to 0.36, and the strength increases to 6.3 to 27.2 MPa. Although these observations indicate excellent cement performance after thermal cycling, its resistance to cyclic loading decreased after thermal shock tests. Additionally, this formulation shows strong plasticity, and our well integrity simulation shows potentially pose risk to the bond between the cement and the casing. 1. INTRODUCTION High Temperature Reservoir Thermal Energy Storage (HT-RTES) is a promising solution for large-scale energy storage that can stabilize the electric grid, increase its flexibility, and provide energy on demand. HT-RTES systems are designed to store large amounts of energy over the long term and contribute to the overall affordability and sustainability of the current energy system (Dobson et al., 2023; Jin et al., 2023). To ensure its high efficiency and low cost, we need effective strategies to prevent heat losses in the system. The wellbore, serving as the conduit connecting subsurface reservoirs to surface heat sources, plays a crucial role in the heat exchange process via heat transfer fluids. Without proper design, significant heat loss could occur across the wellbore, diminishing system efficiency and potentially damaging the cement behind casing, leading to well leakage and total loss of the well (Meng et al., 2023).