Coal Cleat Compressibility & Matrix Strain Calculator

Calculate cleat compressibility \(c_f\) (1/psi), Langmuir matrix shrinkage volumetric strain, and dynamic cleat width changes using the Seidle-Huitt matchstick model.

Cleat Geometry & Coal Elasticity

Initial Cleat Width b_0 (µm):

Cleat Spacing / Block Size a (cm):

Coal Young's Modulus E (psi):

Matrix Shrinkage Constant ε_max (%):

Initial Pressure P_0 (psi):

Current Depleted Pressure P (psi):

Calculated Cleat Strain & Compressibility

Cleat Compressibility c_f:

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Net Cleat Aperture Change Δb:

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Current Cleat Width b:

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Initial Cleat Porosity φ_0:

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Matrix Shrinkage Strain ε_m:

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Seidle-Huitt Permeability Multiplier:

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Frequently Asked Questions

Why are coal cleat widths measured in micrometers (µm)?

Natural coal cleats are hair-thin microfractures typically 5 to 50 micrometers (0.0002 to 0.002 inches) wide. Despite their minute aperture, they provide the entire Darcy fluid conduit for the reservoir because the coal matrix itself has nanodarcy permeability.

How does CO2 injection affect coal cleats during ECBM (Enhanced CBM)?

Coal has an adsorption affinity for carbon dioxide (CO2) that is 2 to 3 times stronger than for methane. When CO2 is injected, the coal matrix swells violently, squeezing cleats completely shut and destroying permeability (often dropping injectivity by 99%).