Study on a new cementitious material waterborne modified epoxy resin under sealed conditions for oil and gas wells

Abstract

Given the poor environmental performance of epoxy resin for oil and gas wells and the lack of research on curing and durability in well conditions, a waterborne modified epoxy resin was synthesized, and then combining with the matched viscosity regulator, curing agent and coagulant, a new cementitious material waterborne modified epoxy resin system was developed for oil and gas wells. The new cementitious material was evaluated by means of macroscopicandmicrocosmictests. The effects of curing conditions and hydrophilic monomer ratio on the solidification of waterborne resin and the long-term durability of resin under well conditions were discussed. Research shows that the safe construction and effective curing of resin under sealed conditions can be realized by adequately controlling the proportion of hydrophilic groups and selecting appropriate regulators. This also ensures that the system is cleanable, safe, and environmentally friendly. This resin system enables effective control of thickening time in the temperature range of 30 to 110 °C. After curing, compared with traditional oil well cement, its compressive strength increased by 81.1 %, Young 's modulus decreased by 62.5 % and Poisson 's ratio increased by 131.6 %. It can significantly improve the mechanical properties of oil well cement stone by film forming, filling, and optimizing pore structure. In addition, microscopic studies have shown that the sealing conditions of wells will seriously affect the curing and crosslinking of traditional waterborne epoxy resins due to the inability of water to volatilize, and it is inappropriate for oil and gas wells to adopt an epoxy resin system cured by volatilization mechanism. The durability of resin after curing under well conditions mainly depends on its glass transition temperature.