Permeability (earth sciences)

About: Permeability (earth sciences) is a research topic. Over the lifetime, 15424 publications have been published within this topic receiving 288535 citations.

Experimental compaction of clays: relationship between permeability and petrophysical properties in mudstones

Abstract: This study determines the relationship between permeability and other petrophysical properties in synthetic mudstones as a function of vertical effective stress. Six brine-saturated clay slurries consisting of smectite and kaolinite were compacted in the laboratory under both controlled pore pressure and proper drained conditions. Porosity, permeability, bulk density, velocity (both V p and V s ) and rock mechanical properties were measured constantly under increasing vertical effective stress up to 50 MPa. The results show that smectite-rich clays compact significantly less and have lower bulk density, velocity, permeability, bulk and shear modulus but higher Poisson9s ratio compared to kaolinite-rich clays at the same effective stress. Kaolinite aggregates compacted to about 26% porosity at 10 MPa effective stress corresponding to about 1 km burial depth in a normally compacted basin, whereas a pure smectite aggregate has a porosity of about 46% at the same stress. The permeability of kaolinite aggregates varies between 0.1 mD and 0.001 mD, while that of smectite aggregates varies from 0.004 mD to 0.00006 mD (60 nD) at stresses between 1 MPa and 50 MPa. Permeabilities in clays show a logarithmic decrease with increasing effective stress, bulk density, velocity or decreasing porosity. At the same porosity or bulk density, permeabilities differ up to five orders of magnitude within the smectite–kaolinite mixtures. Applications of the Kozeny–Carman equation for calculating permeability based on porosity in mudstones will therefore produce highly erroneous results. The relationships between V p , V s , bulk and shear modulus to permeability also vary by up to four orders of magnitude depending on the clay compositions. Velocities or rock mechanical properties will therefore not be suitable to estimate permeability in mudstones unless the mineralogy and textural relationships are known. These experimental results demonstrate that smectite content may be critical for building up pore pressure in mudstones compared to kaolinite. The results help to constrain compaction and fluid flow in mudstones in shallower parts of the basins (

The relation among porosity, permeability, and specific surface of chalk from the Gorm field, Danish North Sea

Abstract: The origin of the difference in the relationship between permeability and porosity for Danian and Maastrichtian chalk from the Gorm field offshore Denmark has been investigated. The investigation was based on 300 sets of core data (He-expansion porosity and air permeability) from Well Gorm N-22X. On 24 of the core plugs, the specific surface was determined by BET and, on 14 of these samples, image analysis was made. The data were rationalized by the use of the Kozeny equation and it was found that each geologic unit had a characteristic relationship among porosity, permeability, and specific surface. Furthermore, it was found that the nature of porosity (intrafossil, intergranular, etc.) had no significant influence on the air permeability, so that the permeability of the chalk can be calculated from total porosity and specific surface. Kozeny’s empirical constant, c, was determined analytically from a simple porosity model and Poiseuille’s law.

Hydraulic Properties and Microgeometry Evolution Accompanying Limestone Dissolution by Acidic Water

Abstract: A reactive flow-through experiment by carbon dioxide-saturated water at the partial pressure of 01 MPa and room temperature was conducted on a porous limestone in order to identify the relationships between fluid chemistry, hydrodynamics and structural properties Periodic imaging by non destructive X-ray microtomography allowed following the evolution of the core micro-geometry and fluid-rock interface in detail while its porosity and permeability increased due to dissolution Several mechanisms were successively involved in the rapid permeability increase Early in the experiment, the permeability increase was related to concomitant particle dissolution and displacement Later on, permeability continued to rise due to solid-fluid interface smoothing and to pore connectivity increase

Frictional stability‐permeability relationships for fractures in shales

Abstract: There is wide concern that fluid injection in the subsurface, such as for the stimulation of shale reservoirs or for geological CO2 sequestration (GCS), has the potential to induce seismicity that may change reservoir permeability due to fault slip. However, the impact of induced seismicity on fracture permeability evolution remains unclear due to the spectrum of modes of fault reactivation (e.g., stable versus unstable). As seismicity is controlled by the frictional response of fractures, we explore friction-stability-permeability relationships through the concurrent measurement of frictional and hydraulic properties of artificial fractures in Green River shale (GRS) and Opalinus shale (OPS). We observe that carbonate-rich GRS shows higher frictional strength but weak neutral frictional stability. The GRS fracture permeability declines during shearing while an increased sliding velocity reduces the rate of permeability decline. By comparison, the phyllosilicate-rich OPS has lower friction and strong stability while the fracture permeability is reduced due to the swelling behavior that dominates over the shearing induced permeability reduction. Hence, we conclude that the friction-stability-permeability relationship of a fracture is largely controlled by mineral composition and that shale mineral compositions with strong frictional stability may be particularly subject to permanent permeability reduction during fluid infiltration.