Experimental Study of Imbibition with Normal Fracturing Fluid in Low-permeability Reservoirs

As the volume of fracturing fluid injected in the formation is getting larger and larger, there is more attention paid to the imbibition efficiency of the broken fracturing fluids. The fracturing fluids, including water-base gel fracturing fluid, thickened water fracturing fluid, slippery water fracturing fluid, emulsified fracturing fluid and clean fracturing fluid were chosen to do the spontaneous imbibition experiment with natural core samples from the Ordos Basin. Furthermore, the correlation between the parameters including viscosity, interfacial tension and contact angle and the recovery ratio was studied respectively. The result showed that the broken fracturing fluids of water-base gel and thicken water performed the highest recovery ratio of spontaneous imbibition, which were 23.1% and 20.6% respectively. Meanwhile, the correlations between those parameters and recovery ratio were contact angle, viscosity of broken fluids and interfacial from in turn in the experimental situation. What's more, both the contact angle and the viscosity showed negative correlation to imbibition recovery ratio while the interfacial tension showed positive correlation. This study provides help to the researchers to understand the mechanism of fracturing fluids imbibition in low permeability reservoirs.