Study on Imbibition Characteristics of Glutenite with Different Boundary Conditions Based on NMR Experiments

A glutenite reservoir is an important unconventional oil resource. However, there are few experimental studies on the imbibition of glutenite, and the imbibition laws with different boundary conditions are not clear. In addition, the one-end-closed (OEC) boundary condition has not received much attention. In this paper, an analytical balance and a nuclear magnetic resonance (NMR) analyzer are used as experimental instruments to monitor the spontaneous imbibition process of saturated oil glutenite in deuterium water, and the imbibition characteristics of glutenite with five different boundary conditions are studied. The T2 spectra show that oil is mainly distributed in micropores and mesopores, and the signal amplitudes in the micropores decrease significantly. The micropores correspond to greater capillary force, and they are the main space for imbibition. The imbibed volume measured by the mass method is basically consistent with the area changes of T2 spectra, and the imbibition curves conform to the Handy model. The imbibition rates with different boundary conditions are different, but their gap is acceptable. Among them, one-end-open (OEO) and two-ends-open (TEO) boundary conditions are slightly higher. Imbibition recovery is related to the exposed areas of the cores, and all-faces-open (AFO) is the boundary condition most conducive to recovery. The normalized recovery model can better scale the three boundary conditions of AFO, OEC, and two-ends-closed (TEC), but there is a certain error in the scaling of TEO and OEO of core end seepage. This research contributes to understanding the effects of boundary conditions on spontaneous imbibition, which is of significance for analyzing the soak mechanism of glutenite reservoirs.