A new plugging agent in drilling engineering of waste rubber powder modified in-situ with radical pentacopolymer

In the drilling operations of oil and gas wells, the temperature resistance and adhesion of plugging agents play a crucial role in preventing the leakage of drilling fluid. In this study, waste rubber powder (WRP) was used as the base material, and styrene (St), 1,3-butadiene (BD), 3-(Trimethoxysilyl) propyl methacrylate (KH570), N-vinylpyrrolidone (NVP), and acrylic acid (AA) were copolymerized and grafted onto the surface and pores of WRP through in-situ free radical polymerization technology, successfully synthesizing a modified rubber powder plugging agent named WRP-K-N-A. WRP-K-N-A was characterized by FTIR, XPS, SEM, and TGA. Rock-soil bonding experiments were conducted to verify its adhesion. The plugging effect of WRP-K-N-A was evaluated through crack plugging simulation experiments. The experimental results showed that WRP-K-N-A has a high temperature resistance of up to 416.83°C and strong adhesion, which helps maintain the integrity of the filter cake structure. In the crack plugging simulation experiment, WRP-K-N-A exhibited excellent plugging ability, with medium pressure filtrate loss and invasion depth stabilizing at 9–11.4 mL and 7.5–12.7 cm, respectively. This study provides theoretical support for the modification of waste rubber powder and its further application in the field of oil well plugging.