A novel temperature-sensitive expandable lost circulation material based on shape memory epoxy foams to prevent losses in geothermal drilling

Lost circulation will inevitably increase non-productive time (NPT) and well cost. The application of high-efficiency lost circulation materials (LCMs) plays an indispensable role in preventing and mitigating loss. The development of new LCMs based on stimuli-responsive materials is an important research direction and it is expected to realize the revolutionary development of LCMs. In recent years, the temperature-responsive plugging agent based on shape memory polymers has caused a lot of attention. In this paper, based on the shape memory epoxy polymer (SMEP) and hollow glass beads (HGBs), a shape memory epoxy foam (SMEF) was successfully synthesized. The results show that the shape memory temperature (51.6 degrees C - 97.5 degrees C) of the SMEPs has a good linear relationship with the content of curing agent 4, 4'-diaminodiphenyl methane (DDM) (12% - 20%), and the expansion ratio (0% - 120.2%) of the SMEFs has a good linear relationship with the content of HGBs (0% - 50%). The mechanism of the SMEFs was proposed. A novel temperature-sensitive and expandable plugging agent (SMP-LCM) has been developed. The plugging experiment shows that SMP-LCM has a good plugging effect on high permeability loss zone simulated by sand beds. Compared with conventional LCMs (e.g., nutshells or fibers), SMP-LCMs can eliminate the risk of plugging of downhole drilling tools and enhance the plugging effect.