Study on in-depth profile control system of low-permeability reservoir in block H of Daqing oil field

According to the geologic characteristics of low-permeability reservoir in block H of Daqing oilfield, three formulations of gel systems for in-depth profile control treatment in this block was optimized by orthogonal experiment and the profile control effect of these systems was evaluated further by core experiment. The results showed that optimal profile control system can effectively block the high permeability core and have little effect on the low permeability core when the injection volume reached 0.6 PV. The changes of water flooding stable pressure was less than 8% within 45 days when its injection volume between 0.6 PV and 0.9 PV. It had a good plugging effect, and it can enhance oil recovery by more than 11%. The profile control system exhibited excellent thermal stability between 60 °C and 80 °C. With the increase of shear times, core plugging rate of the optimized profile control system decreased by less than 1.2%, it means that the plugging performance of profile control agent was less affected in the process of in-depth profile control treatment in oilfield. The application of this profile control system in Daqing Oilfield H block has achieved remarkable results. The water cut decreased by 4.66% and the well group oil productions increased by 21% after the in-depth profile control treatment.