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AAPG Bulletin

Figure

AAPG Bulletin; Year: 2024; Issue: February
DOI: 10.1306/12202222033

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Figure 7. Plot showing the horizontal permeability to dodecane measured in samples from the organic-rich siliceous mudstone (sample PN3-108; squares) and dolomitic calcareous sandstone (sample PND-17; circles) lithofacies (as examples) at the effective stress conditions specified in our test program (see Figure 4). The arrows indicate the direction of loading and unloading paths. The vertical, gray-shaded rectangle represents the range of in situ mean effective stresses ( ${σ'}_{m}$ ) (1038 [7.16 MPa]–1665 psi [11.48 MPa]) inferred for the depths of the samples tested. The relationship between permeability and effective stress during the second unloading path (tests 4–6) is given by fitting the exponential relationship: k = k₀ exp (−α (P_c − P_p) (Best and Katsube, 1995). In sample PND-17, the coefficients are k₀ = 2122 nd and α = 0.0010 MPa⁻¹ (coefficient of determination [R²] = 0.94) (gray dotted line); in sample PN3-108, the coefficients are k₀ = 149 nd and α = 0.0366 MPa⁻¹ (R² = 0.83) (gray dashed line). P_c = confining pressure; P_p = pore pressure.

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