1 Fracture mapping

Fracture mapping is the process of measuring and recording the spatial distribution, geometry, and characteristics of fractures on outcrops, boreholes, or remote sensing images. It can help to identify fracture sets, networks, and domains that control the deformation and fluid flow of the rock mass. For best results, it is important to use a consistent method and terminology to describe and classify fractures, such as the scanline, window, or circular scan methods, and the ISRM or Barton-Bandis schemes. Appropriate tools and instruments should be used to measure fracture parameters like orientation, spacing, length, aperture, roughness, and filling (e.g., a compass, a tape measure, a ruler, a caliper, a camera, or a digital device). The scale and resolution should also be chosen based on the purpose and scope of study (e.g., regional, local or detailed scale; coarse, medium or fine resolution). Additionally, a representative sampling strategy should be used to avoid bias (e.g., random, systematic or stratified sampling method; considering spatial autocorrelation and anisotropy). Finally, standard format and software should be used to store data (e.g., spreadsheet or database) as well as specialized software for visualization (e.g., Stereonet), modeling (e.g., FracPaQ), and interpretation (e.g., DFN).

2 Fracture sampling

Fracture sampling is the process of collecting and processing rock samples that contain fractures or are affected by fractures. This procedure can help you to determine the mineralogy, geochemistry, and geomechanics of fractures and their host rocks. To ensure the best results, it is important to use a clear objective and criterion to select relevant and representative samples. The appropriate techniques and equipment should also be used to extract and transport the samples without damaging or altering them. Additionally, adequate methods and protocols should be employed to prepare and analyze the samples in the laboratory or in situ. Finally, a consistent system and software should be used to document, organize, and report your results.

3 Fracture environments

Fractures can form in various environments that reflect the geological history and processes of the rock mass, as well as interact with the environmental factors that affect their evolution and behavior. Examples of common fracture environments include tectonic, volcanic, and sedimentary. Tectonic fractures are related to the stress field and deformation of the crust, such as faults, folds, shear zones, or joints. Volcanic fractures are related to magma emplacement and cooling, such as dykes, sills, veins, or cooling joints. Sedimentary fractures are related to sediment deposition and diagenesis, such as bedding planes, stylolites, or dissolution features. By understanding these fractures, we can gain insight into the kinematics, dynamics, composition, temperature of magma, lithology, stratigraphy, and paleoenvironment of the sediments.

4 Fracture characterization

Fracture characterization is the process of describing and quantifying the properties and attributes of fractures and their host rocks. This can help understand the structural and hydrogeological significance of fractures and their effect on rock mass behavior. Key aspects of fracture characterization include fracture geometry, which refers to the shape, size, spatial distribution, and orientation of fractures; fracture filling, which is the material that occupies the fracture space such as minerals, fluids, or gases; fracture roughness, which is the irregularity and variability of the fracture surface; and fracture mechanics, which is the deformation and failure modes of fractures under different stress conditions. All these aspects can affect the connectivity, permeability, strength, aperture, friction, flow, stability, integrity, and durability of a rock mass.

5 Fracture modeling

Fracture modeling is the process of creating and simulating numerical or physical representations of fractures and their host rocks. This technique can help predict and optimize the performance and behavior of the rock mass in various applications and scenarios. There are three main types of fracture modeling: discrete fracture models, equivalent continuum models, and hybrid models. Discrete fracture models explicitly represent each individual fracture with its own geometry and properties, allowing for a complex and heterogeneous fracture network. Equivalent continuum models implicitly represent the fracture effects as an equivalent continuum with effective properties. Hybrid models combine discrete fracture models and equivalent continuum models to represent different scales or domains of fracture influence, balancing accuracy with efficiency.

6 Here’s what else to consider

This is a space to share examples, stories, or insights that don’t fit into any of the previous sections. What else would you like to add?