A core-scale reconstructing method for shale.

Area of Science:

• Geology
• Petroleum Engineering
• Materials Science

Background:

• Shale core characterization is challenging due to complex multiscale pore structures and thin layers, hindering conventional analysis.
• Accurate pore structure representation is crucial for understanding low and anisotropic permeability in shale reservoirs.

Purpose of the Study:

• To develop a novel core-scale reconstructing method for creating 3D digital-experimental models of shale cores.
• To accurately reproduce the morphology of multiscale pore structures, including nano-organic pores, micro-nano inorganic pores, and micro-slits.

Main Methods:

• Combines Scanning Electron Microscopy (SEM), Energy Dispersive Spectroscopy (EDS), nitrogen adsorption, and pressure pulse decay experiments.
• Utilizes a multiscale and multicomponent reconstructing algorithm and a simulated annealing optimization algorithm constrained by experimental data.
• Integrates layer-specific models, incorporating bedding fractures derived from mineral distribution analysis, to form the final core-scale model.

Main Results:

• Successfully generated 3D digital-experimental models that accurately represent the complex pore morphology of shale cores.
• Validated the model's accuracy by comparing computed morphological and flow properties with those of actual 3D shale samples.
• Demonstrated the capability to systematically describe anisotropic pore structures across multiple scales (nm-cm).

Conclusions:

• The proposed method offers a robust approach for detailed characterization of shale core pore structures.
• This digital-experimental modeling technique provides valuable insights into shale reservoir quality and fluid flow behavior.
• The method overcomes limitations of conventional techniques for analyzing low and anisotropic permeability shale.