Synthesis and Properties of a Novel Salt-Resistant Block Copolymer Aps for Oilfield Fracturing Thickening Agent

Abstract

Taking the fracturing requirement of the ultra-high-salinity reservoirs into account, we describe a novel segmented ternary copolymer through the macromolecular design principle as fracturing fluid thickening agent. The copolymer (APS) was block copolymerized by acrylamide (AM), 2-acrylamido-2-methylpropanesulfonic acid (AMPS), and sodium p-styrenesulfonate (SSS). According to the orthogonal experiment design and range analysis, we achieved the optimum APS synthesis technology route. The APS sample was evaluated by salt resistance and high-temperature tolerance test. Meanwhile, the rheological properties and breaking capability of the fracturing fluid system APS + BPA were also measured at high-temperature and high-salinity condition. The APS thickening agent exhibits more excellent salinity-resistant and high-temperature-tolerant ability than the normal AM/AMPS thickener. The fracturing fluid system APS + BPA also shows the outstanding rheological property at high-temperature and ultra-high-salinity condition. Besides that, the APS + BPA system also exerts the good breaking capability, which could meet the demand of oil field construction. The above results indicated that the existence of SSS could obviously improve the rheological property at ultra-high-salinity condition. It is well known that the –SO₃H⁻ group exerts good salt tolerance. The introduction of benzene ring could increase the density of electron around –SO₃H⁻ group and then further enhance the hydration capacity as well as stability at ultra-high-salinity condition. In this study, we induce the benzene sulfonic acid group into the conventional fracturing fluid through block copolymerization method, which greatly improves the salinity-resistant ability at high temperature compared with traditional fracturing fluid. Therefore, the technology provides the possibility for the ultra-high-salinity oilfield fracturing operation.