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Explore a groundbreaking research on fluid flow in fractured rocks, using CT scanning and computer simulations to analyze single-phase and two-phase flows in fractures. The study introduces a novel empirical equation for fracture friction factor and provides detailed insights on pressure drops and velocity profiles through fractures.
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A New Friction Factor Correlation for Laminar and Single-Phase Fluid Flow through Fractured Rocks K. Nazridoust, G. Ahmadi, and D.H. SmithDepartment of Mechanical and Aeronautical Engineering Clarkson University, Potsdam, NY 13699-5725National Energy Technology LaboratoryU.S. Department of Energy, Morgantown, WV 26507-0
Outline • CT Scanning Procedures of Fractured Rocks - Geometric Features of Fractures • Single Phase Flows through Fractures - Velocity and pressure contours • Gas-Liquid Flows - Water Flooding in Oil Saturated Fractures • Conclusions
C.T. Scanning of Fractured Rocks
0.5 mm HD-250 Medical C.T. Scanner
OMNI-X Scanner - Penn State Source Detector Rock sample in the pressure vessel
Healed Natural Fracture Open Artificial Fracture
Fractures Topology Sample diameter is 25 mm. Inset size is 5x5 mm.
aperture length Extracting Digital Fracture
Fracture/Sections C.T. Scan Images 240 Micron Resolution
Fracture Sections No-slip Wall Inlets
Governing Equations Continuity Momentum ParallelPlate Model, Laminar Flow For ith passage : Tortuosity Friction Factor Average aperture height
Pressure Drop Air Water
Friction Factor Friction Factor for Laminar Flow between Parallel Plates Friction Factor for Laminar Flow in Fractures
Two-Phase Flows Water-Oil
Volume Fraction during Water Flooding Water Oil
Velocity Magnitude Contours During Water-Oil Flow on a Plane across Fracture Shaded region is the fracture opening which is made transparent so that the flow can be observed. White regions are rock. The contours are shown on a plane through the fracture.
Volume Fraction of Oil During Water-Oil Flow on a Plane across Fracture
Two-Phase Air-Water Flows though a Multi-Branch Fracture
Air-Water Flow in a Multi-Branch Fracture Velocity Magnitude Contours Air Volume Fraction Contours
Air-Water Flow in a Multi-Branch Fracture Air Volume Fraction Contours
Air-Water Flow in a Multi-Branch Fracture Water Volume Fraction Contours on a Plane
Air-Water Flow in a Multi-Branch Fracture Velocity Magnitude Contours on a Plane
Conclusions • The computer simulation technique is capable of capturing the features of the flow through the fracture. • The simulation results are in qualitative agreement with the parallel plate model. • The newly proposed empirical equation for fracture friction factor provides reasonably accurate estimates for the pressure drops in fractures for range of Reynolds numbers less than 100. • A significant portion of the fracture pressure drop occurs in the areas with smallest passage aperture.
Conclusions • The order of the magnitude of the pressure in various sections of the fracture is consistent with the number of passages with smallest aperture that are present in those sections. • The tortuosity of the fracture passage is an important factor and needs to be included in the parallel plate model.