Experimental modeling of multiphase flow in low-permeability reservoirs using low-frequency nuclear magnetic resonance relaxometry

UDK: 622.276.031.011.433:556.822.3

DOI: 10.24887/0028-2448-2025-7-99-105

Key words: low-permeability reservoir, tight sandstone, Achimov deposits, relative phase permeability, nuclear magnetic resonance, pore size distribution

Authors: A.Z. Mukhametdinova (Skolkovo Institute of Science and Technology, RF, Moscow); T.I. Yunusov (Skolkovo Institute of Science and Technology, RF, Moscow); D.V. Sergeeva (Skolkovo Institute of Science and Technology, RF, Moscow); D.I. Bakulin (Skolkovo Institute of Science and Technology, RF, Moscow); D.O. Davydov (Skolkovo Institute of Science and Technology, RF, Moscow); P.A. Grishin (Skolkovo Institute of Science and Technology, RF, Moscow); A.N. Cheremisin (Skolkovo Institute of Science and Technology, RF, Moscow)

The main characteristics of unconventional reservoirs include high heterogeneity and anisotropy of the pore space, low permeability due to nanoscale pore channels, significant influence of capillary forces and diffusion, active mass exchange between phases, and the presence of solid, insoluble organic components in the rock matrix. These factors complicate the application of existing physical and mathematical models for accurately describing fluid flow, and affect the precision of recoverable hydrocarbon reserves assessments, including the effectiveness of various development strategies. One of the most important parameters of multiphase flow through porous media is relative phase permeability. Applying conventional laboratory techniques to determine relative phase permeability in these reservoirs is challenging due to the lengthy duration of studies and high errors in phase saturation estimation. This study aims to develop methodological approaches for the laboratory determination of relative phase permeability in low-permeability core samples using nuclear magnetic resonance assisted profiling to determine saturation during core flooding experiments. The research involves determining phase permeability in water-gas and oil-gas systems under reservoir pressure, as well as describing changes in the pore space structure of rocks during gas filtration. The influence of different fluid flow rates is demonstrated through both steady-state and unsteady-state tests on carbonate rocks and tight sandstones. The results obtained show good agreement with data from X-ray scanning experiments conducted on similar core models.

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