Synthesis and plugging performance evaluation of micro-nano polymeric high-temperature resistant plugging agent for water-based drilling fluids

Wellbore instability of deep and ultra-deep formations is critical in the drilling industry. To solve the problem of plugging material failure in high-temperature environments and plug micron-scale pores, it is crucial to develop a plugging agent that can maintain its effectiveness in high-temperature scenarios. In this study, a high-temperature-resistant plugging agent was synthesized by emulsion polymerization. The copolymer consisting of acrylamide (AM), 2-acrylamide-2-methylpropanesulfonic acid (AMPS), diallyl dimethyl ammonium chloride (DMDAAC), styrene (St) was named ASDS. ASDS was characterized by Fourier Transform Infrared (FT-IR), thermogravimetric analysis (TGA), particle size distribution, and transmission electron microscopy (TEM). The rheological property and filtration performance of ASDS in various temperature conditions were evaluated by rheological and filtration performance tests, respectively. The experimental results demonstrated that ASDS was smooth and malleable with a median particle size distribution of 1720 nm, and it exhibited good thermal stability with an initial thermal decomposition temperature of up to 316.9 °C. The ASDS maintains persistent plugging performance up to high temperatures of 180 °C for various pore sizes of filter medium. This resulted in a 56.6% reduction in filtration loss with filter paper and a reduction from 122 mL to 60 mL with ceramic sand disks under 180 °C 3.5 Mpa. This paper presents a preparation method for a plugging agent with good plugging performance in high-temperature conditions, which has potential applications in water-based drilling fluids.