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.

Permeability and petrophysical properties of 30 natural mudstones

Abstract: [1] We present permeability and other petrophysical data (including pore size distribution, porosity, particle size distribution, grain density, specific surface area, total carbon content, organic carbon content, and sulphur content) for 30 deeply buried mudstones. Permeabilities were measured at different effective consolidation stresses ranging from 2.5 to 60 MPa with a 30,000 mg L−1 NaCl solution. Samples represent a wide spectrum of mudstone types with clay size particle contents ranging from 13 to 66%. Porosities range from 6 to 27%; pore size data show that porosity loss is driven primarily by collapse of the largest pores. Our results confirm and considerably extend previously reported results indicating the influence of clay content on pore size distributions and the way they evolve as a result of compaction. Vertical permeabilities, measured using the transient pulse decay technique, range from 2.4 × 10−22 m2 to 1.6 × 10−19 m2. Horizontal permeabilities range from 3.9 × 10−21 m2 to 9.5 × 10−19 m2, overlapping with but generally higher than vertical permeabilities. In general, permeability decreases logarithmically with porosity. The relationship between permeability and porosity is strongly influenced by clay content, especially at higher porosities. Ratios of horizontal to vertical permeability measured on four samples range from 1.7 to 11.8, implying the influence of both particle alignment and sedimentological heterogeneity. We have used the data to calibrate two permeability models. For the Kozeny-Carman model, values of 200 and 1000 for the product of shape and tortuosity factors provide the best fit for the vertical and horizontal permeabilities, respectively. The calibrated Yang-Aplin model predicts the permeability of almost all the samples to within a factor of ±3 over a 4 orders of magnitude range of permeability.

Predicting the saturated hydraulic conductivity of soils: a review

Abstract: This paper examines and assesses predictive methods for the saturated hydraulic conductivity of soils. The soil definition is that of engineering. It is not that of soil science and agriculture, which corresponds to “top soil” in engineering. Most predictive methods were calibrated using laboratory permeability tests performed on either disturbed or intact specimens for which the test conditions were either measured or supposed to be known. The quality of predictive equations depends highly on the test quality. Without examining all the quality issues, the paper explains the 14 most important mistakes for tests in rigid-wall or flexible-wall permeameters. Then, it briefly presents 45 predictive methods, and in detail, those with some potential, such as the Kozeny-Carman equation. Afterwards, the data of hundreds of excellent quality tests, with none of the 14 mistakes, are used to assess the predictive methods with a potential. The relative performance of those methods is evaluated and presented in graphs. Three methods are found to work fairly well for non-plastic soils, two for plastic soils without fissures, and one for compacted plastic soils used for liners and covers. The paper discusses the effects of temperature and intrinsic anisotropy within the specimen, but not larger scale anisotropy within aquifers and aquitards.

Method of thermal stimulation for recovery of hydrocarbons

Abstract: A method for improving hydrocarbon flow from a consolidated, tight reservoir rock having authigenic clay cementation includes thermally heating the reservoir rock in-situ surrounding a production well to change the mode of occurrence of clay cements within the rock so as to enhance reservoir permeability and carrying out rapid flowback into the production well.

Theoretical derivation of Darcy's law

Abstract: Darcy's law for anisotropic porous media is derived from the Navier-Stokes equation by using a formal averaging procedure. Particular emphasis is placed upon the proof that the permeability tensor is symmetric. In addition, it is shown that there is a one-to-one relationship between the local and macroscopic velocity fields. This leads to the interesting phenomenological observation that the local velocity vector at any given point must always lie either on a fixed line or in a fixed plane. All of this holds true for an incompressible homogeneous Newtonian fluid moving slowly through a rigid porous medium with uniform porosity under isothermal and steady state conditions. The question whether Darcy's law is applicable under nonsteady or compressible flow conditions, or when the medium has nonuniform porosity, is also discussed. Finally, it is shown that the Hagen-Poiseuille equation, as well as the expression describing Couette flow between parallel plates, can be derived from the equations presented in this work and may thus be viewed as special cases of Darcy's law.