Research on the recovery efficiency of crude oil in tight reservoirs with different pore sizes

Tight reservoirs are rich in microscale pores, and the fluid flow mechanisms are extremely complex. In this paper, firstly, by using the high-temperature and high-pressure static and dynamic throughput experimental equipment and nuclear magnetic resonance instrument, the effects of pressure and imbibition medium on the recovery rate and total recovery rate of different pore sizes under static imbibition conditions of rock cores are studied. Secondly, the effect of soaking time on the recovery rate and total recovery rate of pores with different sizes under dynamic throughput conditions is studied. Results show that: (a) Under static imbibition conditions, pressurization can improve the total recovery efficiency of the two imbibition systems and shorten the imbibition equilibrium time. (b) Under static imbibition conditions, pressurization will reduce the degree of crude oil utilization in microscale pores and macroscale pores, and increase the degree of crude oil utilization in small and mesoscale pores. (c) As the imbibition pressure increases, PAM type slick water reaches the imbibition displacement equilibrium faster than anionic non-ionic surfactants