Abstract
A novel technology has been developed for in-depth profile control based on thermo-gelling polymers (refers as THR). This technology differs from the ones currently used through different aspects. Thermo-gels polymers spontaneously gel when they reach a threshold temperature. Below this temperature, the product behaves as low-viscosity fluid, with good injectivity in reservoir rock. The system is single-component, and does not require any additive, contrary to classical gel systems which need to mix a polymer with a cross-linker (and often additives) to control gelation time. It is thus of easy control and does not face the drawbacks of two- or multi-component gel systems. Moreover this family of products is bio-sourced, thus environmentally friendly (some are CEFAS approved). Different THRs have been developed whose gel temperature varies between 25 and 85°C.
The present work details laboratory evaluation of different THRs, including rheological properties, gel kinetics, gel strength, long-term stability and coreflood experiments.
Main results are as follows: i) gel temperature can be optimized by varying brine salinity and THR type and/or concentration; ii) gel kinetics is very rapid once the gel temperature is reached, iii) THRs remain stable over period of time superior to one year in reservoir conditions; iv) coreflooding experiments in sandstone rocks show moderate adsorption (around 50 μg/g), good injectivity below gel temperature and strong pressure build-up once gel temperature is reached. Gel strength can be as high as 35 bar/m.
