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

Abstract

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 T 2 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 T 2 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.

Nuclear Magnetic Resonance Investigation of Forced Imbibitions in Longmaxi Shales: Consideration of Different Boundary Conditions

“…Regarding the imbibition rates across forced imbibitions, they are not much different in these boundaries, which may be due to the approximate porosity, permeability, and total imbibition volume of these four parallel samples. 32,33 Moreover, the values of imbibition potential are such that TSO > ASO > HSO > OSO, illustrating the different contributions made by late imbibition stages to the whole forced imbibition process. However, these findings are contrary to the previous studies, 31,32,59 which can be attributed to the intrinsic differences of imbibition mechanisms between spontaneous imbibition and forced imbibitions coupled with the boundaries.…”

“…Through the NMR imbibition experiments on fractured shales under three boundaries, Yang et al 32 found that boundary conditions mainly affect the imbibition by changing the movement relationship and contact area between the core and water. Wang et al 33 also conducted NMR experiments to study the imbibition laws of glutenite with ASO, OSO, TSO, one-side-closed, and TSC conditions. Despite considerable publications on the boundary effects for oil−water imbibitions, there are relatively few research studies focused on the boundary effects for gas−water forced imbibition of gas shale.…”

Mechanisms of Imbibition Diffusion and Recovery Enhancing of Fracturing Fluids in Tight Reservoirs

“…52 The impact of pressure pulse imbibition was examined by Wang et al The findings of their research suggest that imbibition recovery was greatest in conditions of extreme pressure and temperature. 53,54 Hou et al conducted an investigation on the process with affecting variables involved in spontaneous pressurized pulse imbibition. They discovered that the recovery process for stress pulse imbibition exhibited an increasing trend as the permeability matrix grew.…”

“…When there are alterations in the core and effective stress, compaction can result in some of the contents within the pore space being expelled from the matrix, subsequently enhancing the imbibition recovery . The impact of pressure pulse imbibition was examined by Wang et al The findings of their research suggest that imbibition recovery was greatest in conditions of extreme pressure and temperature. , Hou et al conducted an investigation on the process with affecting variables involved in spontaneous pressurized pulse imbibition. They discovered that the recovery process for stress pulse imbibition exhibited an increasing trend as the permeability matrix grew. , Saad et al conducted imbibition experiments on matrix, matrix-single, and matrix-crack network samples to explore the influence of natural cracks on imbibition .…”