Delayed expansion behavior and mechanical properties of water-swelling rubber/OMMT composites

Abstract

To meet the harsh water plugging conditions for a crack fracture-type rock reservoir of Tahe oilfield in China, which are high temperature, high salinity and above 4000 m underground, a novel delay-expansion water-swelling rubber/OMMT (DWSR) with silty-resistant and lower hydrophilic resin migration behavior was developed. HNBR, semi-HEMA@PU, polyacrylamide (PAM), OMMT and other rubber additives were mechanically blended in an open mill mixer. The semi-HEMA@PU blocked by double bond and isocyanate group was prepared by the reaction of NCO group (50% mole fraction) with hydroxyethyl methacrylate. The semi-HEMA@PU reacted with the amino group from PAM and the unsaturated double bond of HNBR, respectively. A crosslink network constructed among PU, PAM and HNBR matrix made the DWSR/OMMT composite exhibit high salinity resistance and low hydrophilic resin migration features. With an increase of PU content, the crosslinking density of DWSR increases gradually. When the semi-HEMA@PU content was 10 phr, the tensile strength reached a maximum of 13.6 MPa. The influences of OMMT content on swelling behavior were investigated. When the mass content for OMMT was about 1phr, the delayed expansion time was more than 50 h. The presence of OMMT significantly improved the delayed expansion property of DWSR.