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Questions and Answers
Fracture orientations can be related to specific geological ______ and structural events.
Fracture orientations can be related to specific geological ______ and structural events.
parameters
Changes in orientation can be caused by later fault movement associated with variations in tectonic ______ through time.
Changes in orientation can be caused by later fault movement associated with variations in tectonic ______ through time.
stress
Fractures are three-dimensional (3D) features and their distribution is generally ______.
Fractures are three-dimensional (3D) features and their distribution is generally ______.
heterogeneous
Natural fractures are usually assumed to have been created by tectonic ______.
Natural fractures are usually assumed to have been created by tectonic ______.
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Well logs such as borehole micro-scanners are used to analyze the ______ and probable production rates.
Well logs such as borehole micro-scanners are used to analyze the ______ and probable production rates.
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Large fractures induced from drilling conditions are usually long straight cracks in an axial position on opposite sides of the ______.
Large fractures induced from drilling conditions are usually long straight cracks in an axial position on opposite sides of the ______.
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Fractures provide an interface with the matrix that is much larger than the ______.
Fractures provide an interface with the matrix that is much larger than the ______.
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Fractures are often detected while drilling by massive lost circulation, sudden pressure ______ or drilling breaks.
Fractures are often detected while drilling by massive lost circulation, sudden pressure ______ or drilling breaks.
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Factors controlling the occurrence of natural, open, permeable fractures include changes in rock properties such as ______ and bedding.
Factors controlling the occurrence of natural, open, permeable fractures include changes in rock properties such as ______ and bedding.
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High-resolution logs, such as the Formation Micro-Scanner or ______ tool, are the best means of describing the fracture geometry.
High-resolution logs, such as the Formation Micro-Scanner or ______ tool, are the best means of describing the fracture geometry.
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Fractures are usually formed during ______ or doming of a reservoir.
Fractures are usually formed during ______ or doming of a reservoir.
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The fracture opening or aperture, ε, requires some ______.
The fracture opening or aperture, ε, requires some ______.
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In areas where the reservoirs have little matrix permeability, fractures are critical to ______.
In areas where the reservoirs have little matrix permeability, fractures are critical to ______.
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The main differences between electrical images and acoustic images relate to the resolution and depth of ______ of the measurements.
The main differences between electrical images and acoustic images relate to the resolution and depth of ______ of the measurements.
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Borehole imaging and 3D seismic surveys have improved ______ mapping.
Borehole imaging and 3D seismic surveys have improved ______ mapping.
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Fracture density, or the 'intensity' of fracturing, is defined as the number of fractures per unit ______ inside an interval of a defined height.
Fracture density, or the 'intensity' of fracturing, is defined as the number of fractures per unit ______ inside an interval of a defined height.
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Study Notes
Fractured Reservoirs - Elective I
- Fractures are three-dimensional (3D) features with heterogeneous distribution.
- Well logs (e.g., borehole micro-scanners) analyze fractures in wellbores to determine aperture and production rates.
- Fractures are crucial in tight reservoirs, not necessarily for oil storage, but for influencing flow.
- Fracture volume, although potentially small compared to reservoir volume, significantly increases matrix-reservoir interface.
- Factors influencing fracture occurrence include folding/faulting, in-situ stresses, and rock properties (porosity, bedding).
- Fractures are often concentrated in low-porosity rocks (e.g., during folding or doming).
- In reservoirs with low matrix permeability, fractures are crucial for productivity.
Fracture Detection and Analysis
- Borehole imaging and 3D seismic improve fault and fracture mapping.
- Fractures typically form parallel or perpendicular to faults (normal, reverse, oblique).
- Fracture density (number of fractures per unit length) is a key parameter corrected for orientation changes.
- Fracture orientations are correlated to geological parameters and structural events.
- Fault-related fractures are less abundant than those associated with folding.
- Recognizing faults involves identifying bedding planes.
- Natural fractures are often created by tectonic stress and are more common in brittle rocks (carbonates, igneous, metamorphic).
- Induced fractures are often long, straight cracks on opposite borehole sides.
- Fractures can be detected during drilling via massive lost circulation, sudden pressure kicks, or drilling breaks.
Fracture Geometry and Measurement
- High-resolution logs (e.g., Formation Micro-Scanner or FMI) help describe fracture geometry.
- Fracture inclination, spacing, and aperture are measurable from imaging logs.
- Electrical imaging logs offer high vertical resolution for fracture analysis.
- Acoustic imaging differs in resolution and investigation depth.
Problems related to Fractured Reservoirs
- Defining fractured reservoirs.
- Tools for detecting fractures.
- Importance of fractures.
- Fracture intensity.
- Common fracture types (Lithology).
- Fault-related fractures vs. folding-related fractures.
- Detecting fractures from induced drilling activities.
- Mud circulation limitations in fracture detection.
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Description
This quiz focuses on the critical role of fractures in fractured reservoirs, examining their influence on flow and production rates. Key concepts include fracture detection techniques and the relationship between fractures and rock properties. Test your understanding of how fractures affect reservoir productivity and the methods used for their analysis.
