Yunlai Yang

TL;DR: In this article, the authors used the data to calibrate two permeability models, the Yang-Aplin model and the Kozeny-Carman model, for 30 deeply buried mudstones with different effective consolidation stresses and a 30,000 mg L−1 NaCl solution.

TL;DR: In this article, the relationship between porosity and porosity for fine-grained clastic sediments (“mudstones”) is investigated and it is shown that much of the range can be explained by variations in lithology, which is defined simply and pragmatically by clay content (mass fraction of particles less than 2 microns in diameter).

Abstract: This paper describes a series of experiments designed to investigate the influence of lithology on the compactional loss of porosity and permeability in mudstones. Two intact samples of London Clay with clay fractions of 40% and 67% were compacted to 33 MPa effective stress. Clay fraction, permeability, porosity, pore size distribution, and specific surface area were measured and their evolution was monitored throughout the compaction process. Electron microscopy was combined with mercury porosimetry to trace the collapse of the pore structure with increasing effective stress. In both cases, porosity loss occurred primarily by the collapse of large pores. This process is more obvious in the coarser-grained sample because throughout the compaction process it has a much broader range of pore radii and a much greater mean pore radius. Consistent with the pore size distributions, the permeability of the coarser sample ranges from ∼ 10−10 m s−1 to 10−12 m s−1 while that of the finer-grained sample ranges from ∼4 × 10−12 m s−1 to 5 × 10−14 m s−1 during progressive compaction from 2 to 33 MPa. The compressibility of the finer-grained sample is greater than that of the coarser-grained sample (0.15 as opposed to 0.07). However, in both cases the compressibility is much lower than that inferred for lithologically similar samples compacted over geological timescales. The demonstration that both porosity and lithology (clay fraction) influence the permeability of mudstones should allow the development of more realistic porosity-permeability relationships which take into account lithological variations exhibited by mudstones.

TL;DR: In this paper, the authors derived a model which uses pore shape, pore throat size distribution and pore alignment as key inputs to estimate the vertical and horizontal permeability of eleven mudstones from the Norwegian Margin.

TL;DR: In this paper, the authors examined the role of faults and fractures as fluid conduits in mudstones and inferred the occurrence of microscopic hydrofractures from the observation that fluid pressures in sedimentary basins rarely exceed minimum leak-off pressures.