Dynamic rheology and relaxation time spectra of oil-based self-degradable gels

In oil well treatments, such as matrix stimulations or water shut-off, it is often necessary to temporary isolate or protect productive zones with chemical diverting agents. In this work, a solution of peroxide crosslinked styrene-butadiene rubber (SBR) has been transformed to a self-degradable gel system by adding hydroperoxide as a degradation agent to the formulation. This oil-based self-degradable gel has been characterized by linear oscillatory rheometry. In situ and ex situ experiments were performed to evaluate the evolution of crosslinking and degradation reactions, including the liquid-solid transition. Relaxation time spectra were calculated from dynamic mechanical frequency sweeps. Structural changes in the polymer network were visible within the relaxation time spectra, since it qualitatively showed the contribution of local simple entanglements and chemical covalent bonds to the final rheological behavior. The influence of peroxide concentration, polymer concentration, hydroperoxide concentration, and temperature have been studied and described in terms of rheological changes. Finally, a hydrogen donor aromatic solvent was used as scavenger to retard both crosslinking and degradation reactions. (c) 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2016, 54, 433-444