A New Method for Artificial Core Reconstruction of a Fracture‐Control Matrix Unit

Abstract

The fracture-control matrix unit (F-CMU) is a special body present in low-permeability fractured reservoirs that can be distinguished by a fracture system and a matrix system. The imbibition phenomenon of the F-CMU provides the possibility for secondary development of low-permeability fractured reservoirs because of the driving force including capillary force and gravity. However, the F-CMU is difficult to obtain during the field core drilling, which has limited the development for laboratory dynamic imbibition tests. Therefore, a new F-CMU reconstruction method is proposed in this study. According to the geometry and parameters, combining laser engraving technology, the fracture system is designed and engraved. Then, the F-CMU is established using a three-dimensional (3D) printed material called polyvinyl alcohol (PVA) as fracture support material which has a faster dissolution rate and causes less damage to the core due to water being the solvent. Finally, the porosity, permeability, and wettability of the matrix system and the T2 spectra from nuclear magnetic resonance (NMR) before and after reconstruction are measured. In addition, numerical simulation calculation of F-CMU permeability is performed. The results show that the characteristic parameters of the matrix system hardly change, indicating low damage to the core. The reconstructed fracture system is found on the T2 spectra, and the fracture permeability is consistent by comparing with the experimental and numerical simulation results. The permeability of the fracture system is about 104 orders of magnitude of the matrix system, which is closer to real core and meets the requirements needed for dynamic permeability experiments.

Research Advance on the Diagnosis Technology of Hydraulic Fractures in Shale Reservoirs

“…Near-wellbore measurement methods often use radiotracers to monitor wellbore data (Guo et al, 2019;Liu et al, 2018;Jin et al, 2021;Liu et al, 2020a). Different radioactive materials were put into the fracturing fluids, gamma spectrum was measured by using a logging instrument, the distribution of the proppant was obtained, and then the fracture height and width were calculated (Gulrajani and Romero, 1996;Shi et al, 2017;Liu et al, 2020b), as shown in Figure 1C.…”

Spontaneous Imbibition in Nanomatrix–Fracture of Low Permeability Using Multiscale Nanofluidic Chips

“…The in situ visualization of instant transport phenomena becomes impossible due to the opacity of the core. Additionally, core experiments are often associated with lengthy experimental periods, cumbersome operations, and limitations in representing the multiscale matrix–fracture structure …”

“…Additionally, core experiments are often associated with lengthy experimental periods, cumbersome operations, and limitations in representing the multiscale matrix−fracture structure. 32 Microfluidic technology, with its unique advantages of customizability, real-time in situ visualization, and economic efficiency, has emerged as a potent tool for researching flow in porous media. 33,34 Microfluidic chips can serve as a dynamic complement to "petrological sheets" by simplifying the pore/ throat structure while preserving the essential characteristics of natural tight formations.…”

Experimental Study on Waterflooding Characteristics of a Large-Scale Physical Low-Permeability Model Based on a Similarity Criterion

“…The one-dimensional core was fractured using advanced techniques such as radial extrusion and laser engraving. 19,20 Additionally, low-field nuclear magnetic resonance technology was employed to dynamically monitor the fluid saturation changes during the displacement process in FMDS. 21 While one-dimensional natural cores and cylindrical artificial cores offer improved simulation of formation heterogeneity conditions, their limited size prevents accurate and effective representation of fractured reservoirs.…”

“…At present, physical models employed for simulating displacement processes, prognosticating productivity, and assessing the efficacy of operational measures in oil and gas field development predominantly encompass the one-dimensional sand-filled pipe/core model, 2D flat plate model, and 3D model. The one-dimensional core was fractured using advanced techniques such as radial extrusion and laser engraving. , Additionally, low-field nuclear magnetic resonance technology was employed to dynamically monitor the fluid saturation changes during the displacement process in FMDS . While one-dimensional natural cores and cylindrical artificial cores offer improved simulation of formation heterogeneity conditions, their limited size prevents accurate and effective representation of fractured reservoirs.…”