Self-Degradable Rubber Plug for Temporary Plugging and Its Degradation Mechanism.

Abstract

A self-degradable rubber plug (SDRP) was developed to address issues in existing crosslinked polymer temporary plugging technology, such as poor self-degradation properties. The synthesis formula was optimized using response surface analysis, resulting in an optimized composition of the SDRP: 13 wt% monomer, 0.02 wt% initiator, 0.7 wt% crosslinker, and 1.8 wt% degradation catalyst. Under the condition of 70-120 °C, the SDRP was transformed from a liquid to a solid gel in 30-110 min; the degradation time was 3-10 days, and the viscosity of the completely degraded solution was lower than 20 mPa·s. At an injection volume of 1 PV SDPR, a breakthrough pressure of 8.34 MPa was achieved. The hydrolysis of the unstable crosslinker was found to have caused the breakage of the SDRP. Over time, the functional groups within the unstable crosslinker underwent hydrolysis due to the combined effects of temperature and the degradation catalyst. This process led to the disruption of crosslinking points, resulting in a gradual deterioration of the network structure. As a consequence, some immobile water was converted into free water. The mobility of water molecules increased until the plug was completely degraded into a viscous liquid. This study enriches the temporary plugging gel system.