Application of Elastomer Microsphere Particles as Water-Based Drilling Fluid Lost Circulation Material

Summary

Lost circulation is a common issue during oil and gas well drilling, presenting significant safety hazards and resulting in substantial economic losses. Bridging materials typically exhibit limited deformation and poor adaptability to formation pores and fractures, primarily due to size mismatching. Polymer gel materials have the potential to address these issues effectively. While strength is a crucial factor affecting plugging performance, other properties—such as the toughness and elasticity of polymer gel particles—are often overlooked. In this research, we introduce a novel elastomer plugging material that exhibits high toughness and elasticity. The material is composed of polyampholytes, which are synthesized through the copolymerization of an acrylate monomer with long alkyl side groups and a pair of oppositely charged monomers. The acrylic monomer enhances the mobility of the polymer chain, while the oppositely charged monomer generates a gradient interaction, resulting in the formation of ionic aggregates with a broad range of sizes and stiffness. The multigradient strong interaction affords the elastomer remarkable strength and elasticity, which, in turn, safeguards the structural integrity of microsphere particles when subjected to elevated pressure and shear stress. Additionally, the presence of weak interactions, enabled by high mobility, promotes gradual energy dissipation, ultimately enhancing the toughness of the material. PABD [poly (AMPS-BXSZ-DMDAAC)] microsphere particles possess the ability to effectively plug leakage channels by infiltrating pore cracks that are smaller than their own size. Additionally, they can form an elastomer block layer to seal cracks that are larger than their own size, which is facilitated by self-healing through the accumulation of particles and the intermolecular forces between them. As the pressure increases, the plugging layer compresses and becomes more dense, thereby effectively preventing the leakage of drilling fluid into the formation. The experimental results demonstrate that PABD microsphere particles effectively obstruct 8-darcy and 180-darcy consolidated sand trays at temperatures as high as 150°C. Moreover, these particles can be used to seal unconsolidated sand beds of 40−60 mesh, and their plugging performance is significantly enhanced when combined with traditional rubber. This study emphasizes the considerable application potential of elastomer materials in drilling operations.