Imbibition Characteristic of Fractured Tight Sandstone Reservoir

Fracture network stimulation + imbibition replacement is a new attempt to effectively develop tight sandstone reservoirs, and the fractures provide conditions for fluid imbibition replacement. On the basis of nuclear magnetic resonance and pseudo-color processing technology, combined with the imbibition experiments, this paper studies the imbibition process of fractured tight sandstone reservoirs, clarifies the effect of each level of pore-throat on imbibition, and realizes the visualization of the imbibition process. The results show that, in fractured tight sandstone reservoirs, the fluid displacement occurs in fractures first, followed by pore-throat. Most of the imbibition recovery is contributed by the macropore, the contribution of the mesopore to imbibition recovery is very weak, and the contributions of the micropore and the pinhole are even less. In the process of imbibition, capillary force and gravitational force are key parameters controlling fluid flow in pores and fractures. The replacement of fluid normally takes place in the early stage of imbibition, especially on the first day of imbibition, then the imbibition rate gradually decreases and finally tends to be stable.

Automated summary

The study shows that in fractured tight sandstone reservoirs, imbibition replacement mainly occurs in fractures, with macropores contributing the most to imbibition recovery, while mesopores, micropores, and pinholes contribute less. Capillary force and gravitational force are key parameters controlling fluid flow, and fluid replacement mostly happens in the early stages of imbibition.