scholarly journals Formation factor and the microscopic distribution of wetting phase in pore space of Berea sandstone

1992 ◽  
Author(s):  
E.M. Schlueter ◽  
L.R. Myer ◽  
N.G.W. Cook ◽  
P.A. Witherspoon
Keyword(s):  
Pore Space ◽  
Berea Sandstone ◽  
Formation Factor ◽  
Microscopic Distribution

scholarly journals Formation factor and the microscopic distribution of wetting phase in pore space of berea sandstone

1993 ◽  
Author(s):  
E. M. Schlueter ◽  
L. R. Myer ◽  
N. G. W. Cook ◽  
P. A. Witherspoon
Keyword(s):  
Pore Space ◽  
Berea Sandstone ◽  
Formation Factor ◽  
Microscopic Distribution

Salinity dependence of the complex surface conductivity of the Portland sandstone

Geophysics ◽  
2016 ◽  
Vol 81 (2) ◽  
pp. D125-D140 ◽  
Author(s):  
Qifei Niu ◽  
André Revil ◽  
Milad Saidian
Keyword(s):  
Relaxation Time ◽  
Pore Size Distribution ◽  
Pore Size ◽  
Size Distribution ◽  
Pore Space ◽  
Complex Surface ◽  
Surface Conductivity ◽  
Formation Factor ◽  
Polarization Model ◽  
Fluid Conductivity

Induced polarization can be used to estimate surface conductivity by assuming a universal linear relationship between the surface and quadrature conductivities of porous media. However, this assumption has not yet been justified for conditions covering a broad range of fluid conductivities. We have performed complex conductivity measurements on Portland sandstone, an illite- and kaolinite-rich sandstone, at 13 different water salinities (NaCl) over the frequency range of 0.1 Hz to 45 kHz. The conductivity of the pore water [Formula: see text] affected the complex surface conductivity mainly by changing the tortuosity of the conduction paths in the pore network from high to low salinities. As the fluid conductivity decreases, the magnitude of the surface conductivity and quadrature conductivity was observed to decrease. At relatively high salinities ([Formula: see text]), the ratio between the surface conductivity and quadrature conductivity was roughly constant. At low salinities ([Formula: see text]), the ratio decreased slightly with the decrease of the salinity. A Stern layer polarization model was combined with the differential effective medium (DEM) theory to describe this behavior. The tortuosity entering the complex surface conductivity was salinity dependent following the prediction of the DEM theory. At high salinity, it reached the value of the bulk tortuosity of the pore space given by the product of the intrinsic formation factor and the connected porosity. The relaxation time distributions were also obtained at different salinities by inverting the measured spectra using a Warburg decomposition. The mode of the relaxation time probability distribution found a small but clear dependence on the salinity. This salinity dependence can be explained by considering the ions exchange between Stern and diffuse layers during polarization of the former. The pore-size distribution obtained from the distribution of the relaxation time agreed with the pore-size distribution from nuclear magnetic resonance measurements.

scholarly journals Predicting Resistivity and Permeability of Porous Media Using Minkowski Functionals

2019 ◽  
Vol 131 (2) ◽  
pp. 705-722 ◽  
Author(s):  
Per Arne Slotte ◽  
Carl Fredrik Berg ◽  
Hamid Hosseinzade Khanamiri
Keyword(s):  
Surface Roughness ◽  
Predictive Power ◽  
Pore Space ◽  
Random Systems ◽  
Minkowski Functional ◽  
Two Dimensional ◽  
Formation Factor ◽  
Minkowski Functionals ◽  
Functional Value ◽  
Wide Range

AbstractPermeability and formation factor are important properties of a porous medium that only depend on pore space geometry, and it has been proposed that these transport properties may be predicted in terms of a set of geometric measures known as Minkowski functionals. The well-known Kozeny–Carman and Archie equations depend on porosity and surface area, which are closely related to two of these measures. The possibility of generalizations including the remaining Minkowski functionals is investigated in this paper. To this end, two-dimensional computer-generated pore spaces covering a wide range of Minkowski functional value combinations are generated. In general, due to Hadwiger’s theorem, any correlation based on any additive measurements cannot be expected to have more predictive power than those based on the Minkowski functionals. We conclude that the permeability and formation factor are not uniquely determined by the Minkowski functionals. Good correlations in terms of appropriately evaluated Minkowski functionals, where microporosity and surface roughness are ignored, can, however, be found. For a large class of random systems, these correlations predict permeability and formation factor with an accuracy of 40% and 20%, respectively.

Influence of Microgeometry on Membrane Potential of Shaly Sands

1990 ◽  
Vol 195 ◽  
Author(s):  
Pabitra N. Sen
Keyword(s):  
Electrical Conductivity ◽  
Membrane Potential ◽  
Pore Space ◽  
Geometrical Parameters ◽  
Formation Factor ◽  
Water Conductivity ◽  
Shaly Sand ◽  
Local Geology ◽  
Geometrical Factors

ABSTRACTThe microgeometry of the pore space influences the membrane potential Em. and theDC electrical conductivity σ of a shaly sand in a similar manner, independent of the details of the geometry: Em and σ being related via the conductivities of cations and σanions;σ=σcation + σ onion, and Em α σ cation/(σcation + σanion). This explicit relationship is used to investigate the role of the geometrical factors which influence both Em and σ in a related manner. The dependence of σ on the water conductivity σw can be well approximated with four geometrical parameters which can be obtained from the slopes and the interceptsof σ vs. σw curve at high and low salinities. We show that these geometrical factors appear in the expression for Em a well. These geometrical parameters (one of them is the formation factor) vary from rock to rock, and any trend in these parameters depend on the local geology.

A physical model for porosity reduction in sandstones

Geophysics ◽  
1998 ◽  
Vol 63 (2) ◽  
pp. 454-459 ◽  
Author(s):  
Doron Gal ◽  
Jack Dvorkin ◽  
Amos Nur
Keyword(s):  
Elastic Moduli ◽  
Pore Space ◽  
Total Porosity ◽  
Effective Porosity ◽  
High Porosity ◽  
Formation Factor ◽  
Archie’S Law ◽  
Unconsolidated Sands ◽  
Porosity Reduction ◽  
Reduction Mechanisms

The experimental elastic moduli‐porosity trends for clean sandstones can be described by the modified upper Hashin‐Shtrikman (MUHS) bound. One geometrical (but not necessarily geological) realization is: as porosity decreases, the number of the pores stays the same and each pore shrinks while maintaining its shape. This concept of uniform porosity reduction implies that permeability is proportional to the effective porosity squared, and that formation factor is proportional to the inverse of the effective porosity. The effective porosity here refers to the part of the pore‐space that dominates fluid flow. The proposed relations for permeability and formation factor agree well with the experimentally observed values. These laws are different from the often used forms of the Kozeny‐Carman equation and Archie’s law, where permeability is proportional to the total porosity cubed and formation factor is proportional to the inverse of the total porosity squared, respectively. We suggest that the uniform porosity reduction concept be used in consolidated rocks with porosities below 0.3. The transition from high‐porosity unconsolidated sands to consolidated sandstones can be described by the cementation theory: the MUHS moduli‐porosity curves connect with those predicted by the cementation theory at the porosity of about 0.3. This scheme is not appropriate for modeling other porosity reduction mechanisms such as glass bead sintering because, during sintering, the pores do not maintain their shapes, rather they gradually evolve to rounder, stiffer pores.

scholarly journals Complex conductivity of tight sandstones

Geophysics ◽  
2018 ◽  
Vol 83 (2) ◽  
pp. E55-E74 ◽  
Author(s):  
André Revil ◽  
Antoine Coperey ◽  
Yaping Deng ◽  
Adrian Cerepi ◽  
Nikita Seleznev
Keyword(s):  
Pore Space ◽  
Geometric Mean ◽  
Full Range ◽  
Coarse Sand ◽  
Exchange Capacity ◽  
Surface Conductivity ◽  
Frequency Effect ◽  
Complex Conductivity ◽  
Phase Lag ◽  
Formation Factor

Induced polarization well logging can be used to characterize sedimentary formations and their petrophysical properties of interest. That said, nothing is really known regarding the complex conductivity of low-porosity sedimentary rocks. To fill this gap of knowledge, we investigate the complex conductivity of 19 tight sandstones, one bioclastic turbidite, and four sand/smectite mixes. The sandstones and the bioclastic turbidite are characterized by low to very low porosities (in the range of 0.8%–12.3%) and a relatively narrow range of cation exchange capacity (CEC — [Formula: see text]). The sand-clay mixtures are prepared with pure smectite (Na-Montmorillonite, porosity approximately 90%, CEC [Formula: see text]) and a coarse sand (grain size approximately [Formula: see text]). Data quality is assessed by checking that the percentage frequency effect between two frequencies separated by a decade is proportional to the value of the phase lag measured at the geometric frequency. We also checked that the normalized chargeability determined between two frequencies is proportional to the quadrature conductivity at the geometric mean frequency. Our experimental results indicate that the surface conductivity, the normalized chargeability, and the quadrature conductivity are highly correlated to the ratio between the CEC and the bulk tortuosity of the pore space. This tortuosity is obtained as the product of the (intrinsic) formation factor with the (connected) porosity. The quadrature conductivity is proportional to the surface conductivity. All these observations are consistent with the predictions of the dynamic Stern layer model, which can be used to assess the magnitude of the polarization associated with these porous media over the full range of porosity. The next step will be to extend and assess this model to partially saturated sandstones.

Effects of pore and differential pressure on compressional wave velocity and quality factor in Berea and Michigan sandstones

Geophysics ◽  
1997 ◽  
Vol 62 (4) ◽  
pp. 1163-1176 ◽  
Author(s):  
Manika Prasad ◽  
Murli H. Manghnani
Keyword(s):  
Quality Factor ◽  
Wave Velocity ◽  
Pore Space ◽  
Confining Pressure ◽  
Compressional Wave ◽  
Differential Pressure ◽  
Berea Sandstone ◽  
Compressional Wave Velocity ◽  
Stress Coefficient ◽  
Space Deformation

Compressional‐wave velocity [Formula: see text] and quality factor [Formula: see text] have been measured in Berea and Michigan sandstones as a function of confining pressure [Formula: see text] to 55 MPa and pore pressure [Formula: see text] to 35 MPa. [Formula: see text] values are lower in the poorly cemented, finer grained, and microcracked Berea sandstone. [Formula: see text] values are affected to a lesser extent by the microstructural differences. A directional dependence of [Formula: see text] is observed in both sandstones and can be related to pore alignment with pressure. [Formula: see text] anisotropy is observed only in Berea sandstone. [Formula: see text] and [Formula: see text] increase with both increasing differential pressure [Formula: see text] and increasing [Formula: see text]. The effect of [Formula: see text] on [Formula: see text] is greater at higher [Formula: see text]. The results suggest that the effective stress coefficient, a measure of pore space deformation, for both [Formula: see text] and [Formula: see text] is less than 1 and decreases with increasing [Formula: see text].

Fractal Characterization and Petrophysical Analysis of 3D Dynamic Digital Rocks of Sandstone

2021 ◽  
Vol 62 (5) ◽  
pp. 500-515
Author(s):  
Peiqiang Zhao ◽  
◽  
Miao Luo ◽  
Dong Li ◽  
Yuqi Wu ◽  
...  
Keyword(s):  
Fractal Dimension ◽  
Pore Structure ◽  
Fractal Geometry ◽  
Pore Space ◽  
Clay Content ◽  
Coefficient Of Determination ◽  
Formation Factor ◽  
Crucial Issue ◽  
Fractal Parameter ◽  
Fractal Parameters

It is a crucial issue to comprehensively study the relations between microstructure and seepage capacity of porous media. Several physical-based parameters of fractal geometry can analyze the pore structure of rocks, while permeability and electrical conductivity are used to study seepage capacity. In this paper, we first created 3D dynamic digital models of nine different sandstones with varying clay content, cements, and intragranular pores in feldspar. These nine models were divided into three groups. Then, fractal dimension, lacunarity, and succolarity, permeability, and electrical properties of the models were calculated, and their relationships were investigated. We used fractal parameters to interpret the correlation between fluid flow and pore structure as one of the main petrophysical properties of a rock. Results showed that the coefficient of determination for cementation exponent m and fractal dimension is 0.869, while between m and porosity, and succolarity, it is 0.784 and 0.781, respectively. This indicates that the fractal dimension and cementation exponent describe the complexity of pores. The coefficient of determination between permeability and succolarity is 0.975, which is higher than that between permeability and the fractal dimension or porosity. The coefficient of determination between formation factor and succolarity is 0.957, which is higher than that between formation factor and the fractal dimension or porosity. Overall, a stronger relationship between petrophysical parameters, permeability in particular, and succolarity allows this lesser-used fractal parameter to be a good measure for characterizing the connectivity of pore space and pore network.

Detection and Estimation of Dead-End Pore Volume in Reservoir ROCK by Conventional Laboratory Tests

1966 ◽  
Vol 6 (03) ◽  
pp. 206-212 ◽  
Author(s):  
I. Fatt ◽  
M. Maleki ◽  
R.N. Upadhyay
Keyword(s):  
Laboratory Tests ◽  
Saline Solution ◽  
Pore Space ◽  
Flow Behavior ◽  
Reservoir Rock ◽  
Formation Factor ◽  
Pressure Transient ◽  
Reservoir Rocks ◽  
Reservoir Flow ◽  
Dead End

Abstract Conventional laboratory core analysis tests on samples of two limestone reservoir rocks indicate that about 20 per cent of PV is in dead-end pores. These tests (electric logging formation factor. mercury injection capillary pressure and miscible displacement) were carried out on 3/4-in. diameter test plugs. Test results show a clear difference between these samples and sandstone or homogeneous limestone reservoir rock. Although the amount of dead-end pore space can be only roughly estimated, the presence of such pore space seems clearly indicated. Pressure transient studies also show presence of dead-end PV. Although they do not give quantitative results, pressure transient data yield a reasonable estimate of the size of the neck connecting dead-end pores to the main flow channels. Introduction Equations conventionally used to describe reservoir flow behavior contain the implicit assumption that all connected pore spaces contributed to both porosity and permeability. Several authors have pointed out the changes in pressure transient behavior and in electric log interpretation that may result if this assumption is incorrect and, instead, dead-end or cul-de-sac pores are present. There is a need for laboratory tests that can detect presence of dead-end pores in core samples. With such information on hand the petroleum engineer can make more rational use of the mathematical tools now available for analysis of reservoir flow behavior. This paper describes laboratory studies designed to detect and, if possible, give a quantitative measure of dead-end PV in laboratory-size core plugs. Three reservoir rocks were used, two of which were limestones suspected of having dead- end pore spaces and a well-known sandstone, used as a comparison standard, in which there is believed to be little or no dead-end pore space. All the studies were designed to measure the natural dead-end PV; i.e., the pore space which is dead-ended because of rock structure. During multiphase flow in a rock without dead-end pores, some parts of one of the phases can become surrounded by the other, thereby giving (for certain flow behavior) an effective dead-end PV 8,9. Such behavior will not be described here. FORMATION FACTOR THEORY One of the simplest laboratory measurements which can be made on core plugs is the electric logging formation factor F. By definition: (1) where Ro is the resistivity of the core plug saturated with a saline solution of resistivity Rw. Difficulties in using this definition of F may arise when the solid framework of the rock is electrically conducting. These difficulties may be largely circumvented by using a highly conducting saline solution so that the conduction contribution of the solid is negligible. There are no useful theoretical relationships between F and the porosity phi. A widely used empirical relation is the one given by Archie: (2) where m, called the cementation factor, is expected to be a constant for a given type of rock. Pirson shows that for reservoir rocks, m varies from about 1.3 for loosely cemented sandstones to 2.2 for highly cemented sandstones or carbonate rocks. SPEJ P. 206ˆ

Sign in / Sign up

Export Citation Format

Share Document