Abstract:Plugging agent plays a key role in the process of oil development, quality improvement and efficiency enhancement. However, there are some problems such as insufficient plugging strength, short validity period and low water plugging efficiency. Therefore, the research on high-strength plugging system has become areas of research focus. In this paper, a kind of organic cross-linked gel plugging agent was developed. With polyhydroxyethylacrylamide (PHEAA) as the skeleton molecule, 1,6-hexane diisocyanate ( HDI ) as the crosslinking agent, N, N-dimethylformamide ( DMF ) and dimethyl sulfoxide(DMSO)mixed solution as the solvent, an organic plugging system ( ADI ) that can undergo sol-gel phase transition under constant temperature conditions was successfully constructed. The influence of polymer, ( HDI ) content and temperature on the gelation time and gel strength were systematically investigated. The results demonstrate that the strength of the gelled organic gel is proportional to the concentration of the polymer and the concentration of the crosslinking agent, and the gelation time is adversely proportional to the temperature. While the content of PHEAA and HDI increased from 10%, 2% to 16%, 5 %, respectively, the corresponding elastic modulus increased from 991 to 3100Pa, and the viscosity increased from 22400 to 45100 mPa.s, separately. Accompanied with the ambient temperature increased from 45 °C to 125 °C, the gelation time decreased from 3h to 13min. The solid-state transition of the system is mainly attributed to the nucleophilic reaction between HDI and hydroxyl groups in PHEAA. The artificial core plugging experiment confirmed that when the volume of liquid plugging system injected to the core reached to 1 PV, the plugging strength after solidifing could reach up to 26.11 MPa, illustrating the potential application for water plugging and profile control.