Summary of intrinsic permeability, k_i, before and after gas diffusion measurements and diffusion coefficient, D. Note, test BC3 was split into two measurement phases each yielding a separate value. Permeability and diffusion measurements were performed at two different confining stress and backpressure values for sample ES1, that is, 3.1 and 1.5 MPa, and 8.0 and 3.9 MPa for tests ES1A and ES1B, respectively. ‘Correction applied’ indicates minor leakage was detected during diffusion testing and a correction thereafter applied to the data