No abstract

Summary The existence of high conductivity features such as fractures, karst zones, and void space conduits can severely restrict the sweep efficiency of waterflooding or polymer flooding. Preformed particle gel (PPG), as a cost-effective technology, has been applied to control excessive water production. However, conventional PPG has limited plugging efficiency in high-temperature reservoirs with large fractures or void space conduits. After water breakthrough, gel particles can easily be washed out from the fractures because of the lack of particle-particle association and particle-rock adhesion. This paper presents a comprehensive laboratory evaluation of a novel water-swellable high-temperature resistant hyperbranched recrosslinkable PPG (HT-BRPPG) designed for North Sea high-temperature sandstone reservoirs (130°C), which can recrosslink to form a rubber-like bulk gel to plug such high conductivity features. This paper systematically evaluated the swelling kinetics, long-term thermal stability, and plugging performance of the HT-BRPPG. Bottle tests were used to test the swelling kinetic and recrosslinking behavior. High-pressure-resistant glass tubes were used to test the long-term thermal stability of the HT-BRPPG at different temperatures, and the testing lasted for more than 1 year. The plugging efficiency was evaluated by using a fractured model. Results showed that this novel HT-BRPPG could recrosslink and form a rubber-like bulky gel with temperature ranges from 80 to 130°C. The elastic modulus of the recrosslinked gel can reach up to 830 Pa with a swelling ratio (SR) of 10. In addition, the HT-BRPPG with an SR of 10 has been stable for over 15 months at 130°C. The core flooding test proved that the HT-BRPPG could efficiently plug the open fractures, and the breakthrough pressure is 388 psi/ft. Therefore, this novel HT-BRPPG could provide a solution to improve the conformance of high-temperature reservoirs with large fractures or void space conduits.

No abstract

No abstract