| abstract |
The invention relates to the field of drilling in the petroleum industry, in particular to a weakly cross-linked copolymer and its preparation method, its application as a plugging agent, water-based drilling fluid and its application. The weakly crosslinked copolymer contains the structural unit shown in formula (1), the structural unit shown in formula (2) and the structural unit shown in formula (3), and the crosslinked substructure in the weakly crosslinked copolymer The content is 0.1‑1% by weight. The weakly cross-linked copolymer provided by the present invention can be used as a plugging agent in water-based drilling fluids, and can be formed into particles, so that it can adjust its own particle shape by absorbing water and swelling during the drilling process, and is suitable for different formation fractures or pore sizes. Plugging can effectively reduce the fluid loss of drilling fluid. |