Showing papers on "Permeability (earth sciences) published in 1972"

Effect of Overburden Pressure and Water Saturation on Gas Permeability of Tight Sandstone Cores

Abstract: Research conducted to determine the potential of nuclear explosions to stimulate gas production verifies that the gas permeability of tight sandstone cores is markedly decreased with increasing overburden pressure. Water saturation also reduces the gas permeability by a large amount. The relative permeability, however, does not change significantly with overburden pressure.

The role of porosity in filtration VIII: Cake nonuniformity in compression–permeability cells

Abstract: Compression-permeability cells are utilized for measurement of porosity and permeability of compressible cakes. Shortcomings of the cells have tended to be minimized in the literature. Data are presented which show that the stress distribution in typical C-P cells is highly nonuniform because of wall friction. For compressible materials, the porosity and permeability would also be nonuniform. Use of large L/D ratios and minimizing wall friction are essential to proper use of C-P cells.

Aquifer properties of the Permo-Triassic sandstones of the United Kingdom.

Abstract: The potential value of core analysis in hydrogeology is critically examined in the light of the results of a systematic study of the porosity, density and intergranular permeability of the Permo-Triassic sandstones in the United Kingdom, based on the examination of 3500 test specimens. The Thesis begins with an account of the stratigraphy of the sandstones, illustrated by 51 vertical sections. This is followed by a description of the distribution and nature of the samples tested. The principal experimental methods employed were the liquid resaturation technique for measurement of porosity and density, and a gas permeameter was used to determine intrinsic permeability. Equipment systems are described which enable large numbers of samples to be handled rapidly. An improved water permeability test system incorporating sterilising filtration is described and tentative proposals for automated instrumentation are presented. The centrifuge method of measuring specific yield is re-examined. The test data are analysed in two ways: a) by making a detailed comparison of the lithology and physical properties of the test specimens, and b) by considering the porosity and permeability data as probability distributions. The second method permits the aquifer properties of the various sandstone subdivisions in different parts of the U.K. to be quantitatively compared for the first time. The parameter "primary" transmissivity is introduced to describe the intergranular component of transmissivity. Values for this parameter are compared with values for "total" transmissivity derived from analysis of pumping test data from six localities in widely differing hydrogeological environments. It is suggested that this comparison allows some general conclusions to be drawn about the relative importance of intergranular flow in sandstone aquifers. A further comparison is made of the permeability and transmissivity of British and German Triassic sandstone aquifers on the basis of data published by Hauthal (1967) and Durbaum, Matthess and Rainbow (1969). The study was deliberately intended to be of a general nature, so as to provide a firm basis for future me detailed work on the hydrodynamic behaviour of sandstone aquifers in the United Kingdom.

Method for reducing gas production

Abstract: A method for reducing gas permeability in a hydrocarbon bearing subterranean formation having zones of gas permeability and at least two penetrating well bores, comprising the injection into said zones of a basic pH aqueous-thickener slug containing an acidic responsive crosslinking system and acidifying the aqueousthickener slug with carbon dioxide for plugging in situ the zones of gas permeability.

Vertical and Horizontal Laboratory Permeability Measurements in Clay Soils

Abstract: Publisher Summary This chapter discusses the vertical and horizontal laboratory permeability measurements in clay soils The direct measurement of vertical k v and horizontal permeability, k h , of clay soils and the validity of Darcy's law in the materials may be of considerable importance in estimating pore water pressure dissipation, and settlement rates, few measurements with this as the specific purpose have been made The direct laboratory measurement of k h and k v may enable a better estimate of field consolidation behavior to be made in soils with either marked creep properties or a more pervious macro structure This first effect is clearly demonstrated by tests on one undisturbed and three remolded clays Tests to demonstrate the effect of the second point are, at present, being made Darcy's law was generally valid, the exception occurring in organic clay where the permeant was not in chemical equilibrium with the pore fluid and a changing k under constant hydraulic gradient occurred, possibly as a result of particle migration The new permeameter systems functioned well throughout the tests A possible difficulty in the interpretation of radial flow test results because of the smearing at the drains It can be solved by measuring the seepage pressure distribution across the sample base

A Field Test of Micellar Solution Flooding

Abstract: A field test was conducted using a micellar slug for tertiary oil recovery in the Robinson sandstone of the Henry reservoir in southeastern Illinois. The origin of the sandstone was nonmarine fluvial, with 20 percent porosity and 200 md permeability. The micellar slug contained petroleum sulfonate, crude column overhead, isopropanol, nonylphenol, sodium hydroxide and water (500 ppM total dissolved solids). Pusher 500 was the thickening agent in the following polymer flood. The flood water was treated with sodium hydroxide before mixing with the polymer to remove divalent cations. A 63 percent recovery of oil in place after waterflooding was realized.

Transformation of the Tensor Form of Darcy's Law in Inhomogeneous and Anisotropic Soils

Abstract: The transformation of the tensor form of Darcy's law from an arbitrary cartesian coordinate system to one in which the permeability tensor is diagonal is discussed. Matrix equations are developed that allow this transformation to be conveniently performed. This transformation leads in a natural way to a discussion of the ellipses of permeability, which have been used in attempts to find geometrically the direction of the gradient of head given the velocity, and vice versa, in anisotropic media. Equations are derived that allow the magnitude, as well as the direction, of the gradient of head or velocity, as the case may be, to be found from the geometrical constructions; thus the utility of the equations is extended. Finally, the connection between the permeability ellipse and the ellipse of direction, which does not seem to have been previously noted in the literature, is demonstrated, and the implications of the connection are briefly discussed.

Conductivity of fracture proppants in multilayers

Abstract: Laboratory determinations of the permeability of sand and other brittle fracture proppants in multilayers showed that permeability under stress can be affected by the fluid contacting the proppant and by temperature. Brine at higher temperatures decreased permeability of stressed sand under some conditions and there was a continued long-term decrease of permeability. Measurements of turbulence factors for fracture proppants under stress showed that deviations from the Darcy flow are higher than expected. This leads to the conclusion that non-Darcy flow is an important factor under some fracture conditions, particularly in gas wells. Further work is needed to correlate laboratory and field results. Both the environment-sensitive effects and non-Darcy flow indicate that industry can profit significantly by improved materials for propping hydraulic fractures. (13 refs.)

Pocket Permeameter: Hand-Held Device for Rapid Measurement of Permeability: GEOLOGICAL NOTES

Abstract: A "pocket" permeameter has been designed for rapid measurement of rock permeability, both in the field and in the laboratory. The instrument measures the flow of air sucked through a rock sample by a squeeze bulb. The bulb provides a vacuum to establish a radial pressure gradient around the instrument orifice which is pressed against the rock surface. The permeability measurement is indicated by the height to which a marker ball in a flow gauge is raised by the air flow. The permeameter is capable of measuring permeability in the range of 10-250 md on a fairly smooth rock surface. Modification in design can change the range of permeability measured. The instrument is intended as an auxiliary tool and not as a replacement for conventional core analysis. Cost of the materia s used in the device is approximately $20; assembly and calibration require about 3 hours.

Permeability improvement technique

Abstract: A water sensitive subterranean fluid reservoir, a petroleum reservoir, for example, previously damaged by swelling due to contact with water is improved in permeability by treating the reservoir with potassium chloride at about 100* C. for several hours.

Permeability of High Ash Papermill Sludge

Abstract: Most deposits of high ash papermill clarifier sludges contain very high water contents, show little drainage over the years, are unstable, and are subject to large settlements under surface loads. Poor drainability is a major part of the problem. Permeability data presented show the influence of gas bubbles trapped in the sludge mass, solids content, organic content of the solids, and admixtures of lime or flyash on the sludge drainage characteristics. Hydraulic pressures required to eliminate the influence of bubbles on drainage were approximated by an expression which considered Boyle's law and Henry's law of solubility. A threshold gradient, required to initiate flow at low pressures, approached zero when the gas bubbles were eliminated. For a constant solids content, data show that permeability increases with an increase in organic content. Lime or flyash admixtures, used as an aid in sludge dewatering methods, increase the sludge permeability.

Seepage from Trenches through Nonhomogeneous Soils

Abstract: Infiltration from shallow trenches of arbitrary cross-sectional shape and through a layer of nonhomogeneous soil was studied analytically. The soil layer is underlain by a bed of gravel that is represented mathematically by a line of constant pressure. The basic flow equations were derived and the corresponding boundary value problems constructed by use of the perturbation theory. The effect of an exponential variation of the hydraulic conductivity on the quantity of seepage and the free surface is determined. A comparison with the case of constant permeability is made for different layer thicknesses. A triangular trench was chosen to indicate the effect of trench dimensions on the amount of seepage through layers of nonuniform permeability. Curves are presented to illustrate this effect.

An Investigation Into the Flow Behaviour Through Compacted Saturated Fine-Grained Soils with Regard to Fines Content and Over A Range of Applied Hydraulic Gradients

Abstract: A short review is given of research carried out to investigate the validity of Darcy's law as applied to flow through soil systems. The paper is then concerned with the conditions of flow through laboratory compacted saturated fine-grained soils and the results of tests carried out on samples with varying fines content over the range of gradients 0.2 and 12.0 are presented. Some interesting trends are revealed showing that peak deviations from Darcy's law were obtained when the samples had a fines content of about 30 % when using a single size type of coarse grading. (For the purpose of comparison it was assumed that “true” Darcy behaviour was exhibited at a relatively large hydraulic gradient of 12). Using a well-graded coarse fraction the trends were more complex. The evidence suggests particle migration particularly since the clay contents, and hence clay structural effects, were small. Mostly test runs were initiated at a gradient of 1 but a few tests were commenced with this second grading at even smaller gradients, giving “true” Darcy or greater behaviour. The results suggest, where gradients less than 1 should be examined, that occasionally it may be more appropriate even critical that permeability tests be carried out in this range for certain soil types and gradients.

Oil Column Calculations in Stratigraphic Traps

Abstract: Oil columns can be calculated for simple stratigraphic traps if the rock and fluid properties are known or can be estimated. Because oil migration is prevented by capillary pressure in small pores of the trap facies, direct measurements of capillary pressure allow oil columns to be calculated, but such measurements are rare. An alternative is to determine pore size from porosity and permeability data using an empirical equation (Berg, 1970), and then to compute the capillary pressure by an estimate of fluid properties. An example of oil column calculation is the Milbur field, Burleson County, Texas, a lower Wilcox stratigraphic trap. Using core analysis for a nearby well, an oil column of 40 to 70 feet would be expected for the trap, and this estimate agrees reasonably well with actual oil columns of 60 to 75 feet for the field (Chuber, 1972). The most important part of such calculations is the realization that the trapping facies itself can have significant porosity and permeability and yet form an effective barrier to oil migration. The result is that the best oil reservoir may occur down dip from dry holes with porous water sand and oil shows, rather than up dip at the pinchout.

Flow in fissured rocks and effective stresses. Application to hydrocarbon production and to hydraulic fracturing

Abstract: Production of fluids from fissured reservoirs generally decreases with the increase in effective stresses being exerted on the formation. Inversely, reservoir rock permeability in the vicinity of a well increases progressively during hydraulic fracturing as the result of the opening up of natural fissures followed by the development of a main fracture running perpendicular to the smallest main stresses. Variations in rock permeability as a function of variations in effective stresses occur in a reservoir during production and hydraulic fracturing and may be plotted as a single curve whose shape depends on the rate of rock fissuring.