Performance evaluation of optimized preformed particle gel (PPG) in porous media

Abstract

Preformed particle gels (PPGs) are used as conformance control agents to improve oil production and control excess water production. This paper talks about optimized PPGs that are designed for high-temperature and high-salinity oil reservoirs and their synthesize process. The influence of cross linker concentration, size of dry PPGs, injection rate, temperature, permeability, and brine salinity on resistance factor (RF) and residual resistance factor (RRF) of PPG in porous media are investigated. The focus of study is to see how PPGs would perform in porous media by creating flow resistance to injected fluid, hence enhancing the sweep efficiency. A set of 51-cm slim tubes packed with carbonate cores from one of the Iranian oil reservoir is used to evaluate the performance of optimized PPG at wide range of different temperatures and permeabilities.PPG injection pressure increases with cross linker concentration, PPGs particle size, and brine concentration and injection flow rates but decreases with the increase of permeability and temperature during PPG injection. It was shown that increased injection rate does not increase PPG injection pressure to the same level and the reduction in water permeability caused by swollen PPG prepared in high salinity brine is higher than that prepared in low salinity brine. Synthesized PPGs can also change the permeability of different slim tubs to the same level. Resistance factor (RF) and residual resistance factor (RRF) increase with the increase in PPGs particle size, brine salinity and cross linker concentration. But, they decrease with the increase of temperature and the flow rate. Initially RRF increased gradually as the permeability of slim tubes decreased from 395 to 137Darcy but a sharp increase in RFF caused by swollen PPG in low permeability slim tube was observed.