## 1 Introduction  
Shale formations account for about 75% of the world's drilled formations, and the development of shale gas resources is necessary for the global energy market and sustainable economic development [1, 2]. Shale gas resources in the Sichuan Basin are abundant and have great potential for exploration and development in China [3, 4]. Horizontal wells have become the primary drilling method to increase shale gas production, which increases the risk of well wall instability compared to straight wells. Using water-based drilling fluids to drill horizontal shale gas wells can cause hydration and swelling of clay minerals, which can lead to complex downhole accidents, such as stuck drilling and block dropping [5, 6]. Oil-based drilling fluids are natural inhibitors that have proven to be excellent in solving drilling problems due to wellbore instability caused by shale hydration. Oil-based drilling fluids to drill shale gas horizontal wells have become a hot topic [7]. Microporous seams in shale formations are extremely developed, and micrometer and nanopore seams coexist, with nanoscale seams occupying most of the proportions [8, 9, 10]. However, the commonly used plugging materials in drilling fluids are generally in the micron-scale range in size, which cannot effectively seal nanopores. Drilling fluids will invade nano-fractures, leading to fracture expansion and poor formation stability, resulting in wellbore instability [11, 12]. Developing efficient plugging agents is one of the critical aspects of solving well-wall destabilization. [PERSON] et al. [13] developed a new oil-based drilling fluids composite-plugging agent, CPA, which can make the mud cake thinner and denser and significantly reduce shale permeability. However, the size of the plugging agent is too large to plug the nano-porosity. [PERSON] et al. [14] synthesized a styrene-butadiene resin/nano-SiO\({}_{2}\) (SBR/SiO\({}_{2}\)) composite, which can be used in both oil-based and water-based drilling fluids with good temperature resistance and plugging effect. Still, the plugging agent is more likely to agglomerate in oil, the particle size increases significantly, and it cannot plug pores within 200 nm. [PERSON] et al. [15] used oleic acid as a surface modifier to improve the dispersion stability of polystyrene in mineral oil. The plugging agent was resistant to high temperatures of 252 \({}^{\circ}\)C and effectively mitigated the decrease in the mechanical stability of the rock. However, the plugging agent did not significantly reduce the high-temperature and high-pressure filter loss, and the reduction rate of 3% was only 21%. [PERSON] et al. [16] investigated an organic-inorganic nanocomposite (NS-D) as a plugging agent. After being added to the drilling fluids, the filtrate volume was reduced by 90.5%. Still, more of this plugging agent was added, which significantly impacted the drilling fluid's performance and was suitable for water-based drilling fluids. [PERSON] et al. [17] used multi-walled carbon nanotubes (MWCNTs) as the main raw material and modified them using the SI-ATRP method. The modified multi-walled carbon nanotubes have good dispersion stability and a good plugging effect with a small addition, but again, they have only been used in water-based drilling fluids. [PERSON] et al. [18] synthesized a novel temperature- and salt-tolerant micro-crosslinked polyampholyte gel. The gel can resist the high temperature of 200 \({}^{\circ}\)C, effectively reducing the filtration loss of drilling fluids. Unlike the direct plugging of conventional polymer plugging agents, the gel reduces fluid loss by improving the stability of the base fluid suspension. Through research, it has been found that gel polymers are generally used as water plugging agents, plugging malignant leakage, and so on. For example, [PERSON] et al. [19] conducted experimental studies on organochromium gels as water blocking agents, and [PERSON] et al.