Screening and performance evaluation on temperature tolerant and salinity resistant polymer used in the Tahe Oilfield

As oil production continues, the tertiary oil recovery (TOR) has gradually stepped to high-temperature and high-salinity reservoirs, but their harsh situations have stricter requirements on TOR water soluble high-molecular polymers. Therefore, it is in urgent need to develop the oil displacement that are applicable to high-temperature and high-salinity reservoirs. The performances of 19 kinds of temperature tolerant and salinity resistant polymer solutions in the setting of Tahe oil reservoir were researched and the application potentials of polymer flooding in Tahe high-temperature and high-salinity reservoirs were explored. The temperature tolerant and salinity resistant performances of 19 kinds of polymer solutions were evaluated by virtue of the rheometer. It is shown that in the setting of Tahe oil reservoir, NK-2, thermoviscosifying polymer SAV1, K21 and natural high-molecular BP have higher residual viscosity and viscosity residual rate and present good temperature tolerant and salinity resistant performances. These four kinds of temperature tolerant and salinity resistant polymers were evaluated from the aspects of shearing resistance and long-term thermal stability. It is revealed that the natural high-molecular BP is the best in the long-term thermal stability. After 0.05% BP is injected by 0.5 PV, the oil displacement efficiency can be increased by 5.6% on the basis of the primary water flooding.