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 Evaluation of Mishrif Reservoir in Abu Amood Oil Field, Southern Iraq

2021 ◽  
pp. 4758-4768
Author(s):  
Ahmed Hussain ◽  
Medhat E. Nasser ◽  
Ghazi Hassan
Keyword(s):  
Total Porosity ◽  
Effective Porosity ◽  
Oil Field ◽  
Well Logs ◽  
Neutron Density ◽  
High Porosity ◽  
Petrophysical Properties ◽  
Density Method ◽  
Southern Iraq

     The main goal of this study is to evaluate Mishrif Reservoir in Abu Amood oil field, southern Iraq, using the available well logs. The sets of logs were acquired for wells AAm-1, AAm-2, AAm-3, AAm-4, and AAm-5. The evaluation included the identification of the reservoir units and the calculation of their petrophysical properties using the Techlog software. Total porosity was calculated using the neutron-density method and the values were corrected from the volume of shale in order to calculate the effective porosity. Computer processed interpretation (CPI) was accomplished for the five wells. The results show that Mishrif Formation in Abu Amood field consists of three reservoir units with various percentages of hydrocarbons that were concentrated in all of the three units, but in different wells. All of the units have high porosity, especially unit two, although it is saturated with water.

Synthesis of β-SiAlON Porous Ceramics by Filtrational Combustion of Reactive Foams in Nitrogen Flow

2014 ◽  
Vol 1040 ◽  
pp. 418-422 ◽  
Author(s):  
A.S. Maznoy ◽  
Alexander Kirdyashkin ◽  
Ramil Gabbasov
Keyword(s):  
Combustion Synthesis ◽  
Gas Flow ◽  
Pore Space ◽  
Reactive Systems ◽  
Total Porosity ◽  
Ceramic Materials ◽  
Porous Ceramics ◽  
Porous Space ◽  
Initial Structure ◽  
High Porosity

Process of synthesis of porous ceramics via organization of the filtrational mode of combustion synthesis in reactive samples preliminary structured by the method of foaming of slurry is investigated. The Al + SiO2 + N2 system is investigated; the target product of synthesis is β-SiAlON. It is demonstrated that high-porosity ceramic materials inheriting initial structure of the porous space of reactive systems can be fabricated in the filtrational mode of combustion synthesis. This has allowed us to vary the pore space parameters in wide ranges. The β-SiAlON based ceramic materials with total porosity from 40 to 75%, sizes of core elements 250–750 μm, sizes of porous channels 10–200 μm, and specific surface 4–15 mm-1 have been fabricated. It is demonstrated that combustion in reactive gas flow considerably intensifies the process of combustion synthesis.

GAS HAZARD ASSESSMENT IN THE RUDNA MINE, BASED ON ANALYSIS OF POROSITY OF DOLOMITES FROM THE RESERVOIR FORMATION

2017 ◽  
pp. 47-58
Author(s):  
Anna POSZYTEK ◽  
Robert Rożek ◽  
Lidia Dudek
Keyword(s):  
High Pressure ◽  
Pore Space ◽  
Mercury Porosimetry ◽  
Mining Industry ◽  
Effective Porosity ◽  
High Porosity ◽  
Closed Porosity ◽  
X Ray ◽  
Gas Hazard ◽  
Reservoir Potential

Reservoir dolomites saturated with gas under high pressure were found in the ceiling of excavations in a Rudna copper mine in southwestern Poland. Reservoir dolomites are a major concern in the mining industry and the focus of substantial research. High-porosity dolomites are definitively considered "hazardous", but the gas is extracted from the dolomites with low porosity, too. So, it is necessary to know way of gas occurrence in the pore space. This article aims to describe the reservoir potential of the dolomites through pore space characterisation and determine whether the gas can migrate into the excavations. A comprehensive analysis of the distribution of pore size and nature using microscopic observations, X-ray microtomography and mercury porosimetry. The results distinguished three types of dolomites with different porosities: dolomites with high effective porosity, dolomites with reduced effective porosity, and sealed dolomites. Particular attention should be paid to sealed dolomites. Their effective porosity results from mercury porosimetry are very low. However, they also contained 4% closed porosity described from microscopic observations, where gas is accumulated, too. Presence of gas in the closed pores dolomites is a common phenomenon. However, the presence of high-pressure gas traps within locally more porous, microcraced and permeable dolomites is a major threat.

scholarly journals Fluid substitution in shaley sediment using effective porosity

Geophysics ◽  
2007 ◽  
Vol 72 (3) ◽  
pp. O1-O8 ◽  
Author(s):  
Jack Dvorkin ◽  
Gary Mavko ◽  
Boris Gurevich
Keyword(s):  
Elastic Modulus ◽  
Pore Space ◽  
Total Porosity ◽  
Effective Porosity ◽  
Fluid Substitution ◽  
Mineral Phase ◽  
Hydrocarbon Production ◽  
System A ◽  
Alternative Method ◽  
Water Saturated

The traditional method of fluid substitution in porous rock requires the total porosity and the elastic modulus of the mineral phase as input and assumes that the fluid reaches instantaneous hydraulic equilibrium throughout the pore space. This assumption may not be appropriate for shaley sediment because of the low permeability of shale and the resulting immobility of the water in it. To address this problem, we propose an alternative method that uses effective porosity instead of total porosity. Effective porosity is lower than total porosity if porous shale is present in the system. A new, composite mineral phase is introduced, which includes the porous water-saturated shale together with the nonporous minerals and whose elastic modulus is an average of those of its components, including the porous shale. This alternative method increases the sensitivity of the elastic properties of sediment-to-pore-fluid changes and therefore may be used as a physics-based theoretical tool to better explain and interpret seismic data during exploration as well as variations in seismic response as hydrocarbon production progresses.

scholarly journals Triple-Layer Nanocomposite Membrane Prepared by Electrospinning Based on Modified PES with Carbon Nanotubes for Membrane Distillation Applications

Membranes ◽  
2020 ◽  
Vol 10 (1) ◽  
pp. 15 ◽  
Author(s):  
Mohamed R. Elmarghany ◽  
Ahmed H. El-Shazly ◽  
Saeid Rajabzadeh ◽  
Mohamed S. Salem ◽  
Mahmoud A. Shouman ◽  
...  
Keyword(s):  
Carbon Nanotubes ◽  
Vinylidene Fluoride ◽  
Bulk Material ◽  
Total Porosity ◽  
Surface Hydrophobicity ◽  
Membrane Distillation ◽  
Nanocomposite Membrane ◽  
High Porosity ◽  
Triple Layer ◽  
Layer Membrane

In this work, a novel triple-layer nanocomposite membrane prepared with polyethersulfone (PES)/carbon nanotubes (CNTs) as the primary bulk material and poly (vinylidene fluoride-co-hexafluoro propylene) (PcH)/CNTs as the outer and inner surfaces of the membrane by using electrospinning method is introduced. Modified PES with CNTs was chosen as the bulk material of the triple-layer membrane to obtain a high porosity membrane. Both the upper and lower surfaces of the triple-layer membrane were coated with PcH/CNTs using electrospinning to get a triple-layer membrane with high total porosity and noticeable surface hydrophobicity. Combining both characteristics, next to an acceptable bulk hydrophobicity, resulted in a compelling membrane for membrane distillation (MD) applications. The prepared membrane was utilized in a direct contact MD system, and its performance was evaluated in different salt solution concentrations, feed velocities and feed solution temperatures. The results of the prepared membrane in this study were compared to those reported in previously published papers. Based on the evaluated membrane performance, the triple-layer nanocomposite membrane can be considered as a potential alternative with reasonable cost, relative to other MD membranes.

Permeability-porosity transforms from small sandstone fragments

Geophysics ◽  
2006 ◽  
Vol 71 (1) ◽  
pp. N11-N19 ◽  
Author(s):  
Ayako Kameda ◽  
Jack Dvorkin ◽  
Youngseuk Keehm ◽  
Amos Nur ◽  
William Bosl
Keyword(s):  
Pore Space ◽  
Petroleum Industry ◽  
Rock Physics ◽  
Three Dimensions ◽  
Absolute Permeability ◽  
High Porosity ◽  
Drill Cuttings ◽  
Thin Sections ◽  
Numerical Experimentation ◽  
The Absolute

Numerical simulation of laboratory experiments on rocks, or digital rock physics, is an emerging field that may eventually benefit the petroleum industry. For numerical experimentation to find its way into the mainstream, it must be practical and easily repeatable — i.e., implemented on standard hardware and in real time. This condition reduces the size of a digital sample to just a few grains across. Also, small physical fragments of rock, such as cuttings, may be the only material available to produce digital images. Will the results be meaningful for a larger rock volume? To address this question, we use a number of natural and artificial medium- to high-porosity, well-sorted sandstones. The 3D microtomography volumes are obtained from each physical sample. Then, analogous to making thin sections of drill cuttings, we select a large number of small 2D slices from a 3D scan. As a result, a single physical sample produces hundreds of 2D virtual-drill-cuttings images. Corresponding 3D pore-space realizations are generated statistically from these 2D images; fluid flow is simulated in three dimensions, and the absolute permeability is computed. The results show that small fragments of medium– to high-porosity sandstones that are statistically subrepresentative of a larger sample will not yield the exact porosity and permeability of the sample. However, a significant number of small fragments will yield a site-specific permeability-porosity trend that can then be used to estimate the absolute permeability from independent porosity data obtained in the well or inferred from seismic techniques.

Predicted Liquid Water Saturation in Unstructured Pore Networks Based on PEMFC GDL Porosity Profiles

2010 ◽  
Author(s):  
J. Hinebaugh ◽  
Z. Fishman ◽  
A. Bazylak
Keyword(s):  
Liquid Water ◽  
Water Saturation ◽  
Pore Space ◽  
Polymer Electrolyte Membrane ◽  
Gas Diffusion ◽  
Pore Network Model ◽  
High Porosity ◽  
Pore Networks ◽  
Electrolyte Membrane ◽  
Capillary Pressures

An unstructured, two-dimensional pore network model is employed to describe the effect of through-plane porosity profiles on liquid water saturation within the gas diffusion layer (GDL) of the polymer electrolyte membrane fuel cell. Random fibre placements are based on the porosity profiles of six commercially available GDL materials recently obtained through x-ray computed tomography experiments. The pore space is characterized with a Voronoi diagram, and invasion percolation-based simulations are performed. It is shown that water tends to accumulate in regions of relatively high porosity due to the lower associated capillary pressures. It is predicted that GDLs tailored to have smooth porosity profiles will have fewer pockets of high saturation levels within the bulk of the material.

scholarly journals The surface CO2 gradient and pore-space storage flux in a high-porosity litter layer

Tellus B ◽  
2004 ◽  
Vol 56 (4) ◽  
pp. 312-321 ◽  
Author(s):  
Adam I. Hirsch ◽  
Susan E.: Trumbore ◽  
Michael L. Goulden
Keyword(s):  
Pore Space ◽  
High Porosity ◽  
Litter Layer ◽  
Storage Flux

scholarly journals Characterization of reservoir sands using 3D seismic attributes in the coastal swamp area of Niger Delta Basin

2021 ◽  
Author(s):  
Oluwatoyin Khadijat Olaleye ◽  
Pius Adekunle Enikanselu ◽  
Michael Ayuk Ayuk
Keyword(s):  
Seismic Data ◽  
Niger Delta ◽  
Seismic Attributes ◽  
Effective Porosity ◽  
High Porosity ◽  
Hydrocarbon Accumulation ◽  
3D Seismic ◽  
Seismic Attribute ◽  
Niger Delta Basin

AbstractHydrocarbon accumulation and production within the Niger Delta Basin are controlled by varieties of geologic features guided by the depositional environment and tectonic history across the basin. In this study, multiple seismic attribute transforms were applied to three-dimensional (3D) seismic data obtained from “Reigh” Field, Onshore Niger Delta to delineate and characterize geologic features capable of harboring hydrocarbon and identifying hydrocarbon productivity areas within the field. Two (2) sand units were delineated from borehole log data and their corresponding horizons were mapped on seismic data, using appropriate check-shot data of the boreholes. Petrophysical summary of the sand units revealed that the area is characterized by high sand/shale ratio, effective porosity ranged from 16 to 36% and hydrocarbon saturation between 72 and 92%. By extracting attribute maps of coherence, instantaneous frequency, instantaneous amplitude and RMS amplitude, characterization of the sand units in terms of reservoir geomorphological features, facies distribution and hydrocarbon potential was achieved. Seismic attribute results revealed (1) characteristic patterns of varying frequency and amplitude areas, (2) major control of hydrocarbon accumulation being structural, in terms of fault, (3) prospective stratigraphic pinch-out, lenticular thick hydrocarbon sand, mounded sand deposit and barrier bar deposit. Seismic Attributes analysis together with seismic structural interpretation revealed prospective structurally high zones with high sand percentage, moderate thickness and high porosity anomaly at the center of the field. The integration of different seismic attribute transforms and results from the study has improved our understanding of mapped sand units and enhanced the delineation of drillable locations which are not recognized on conventional seismic interpretations.

Numerical analysis of soil microstructure reveals conditions for natural attenuation in aged tar oil contaminated soil

2021 ◽  
Author(s):  
Pavel Ivanov ◽  
Karin Eusterhues ◽  
Kai Uwe Totsche
Keyword(s):  
Soil Solution ◽  
Contaminated Soil ◽  
Natural Attenuation ◽  
Pore Space ◽  
Total Porosity ◽  
Control Soil ◽  
Soil Microstructure ◽  
Cell Counts ◽  
Good Protection ◽  
Tar Oil

<p>Understanding of ongoing biogeochemical processes (natural attenuation) within contaminated soils is crucial for the development of plausible remediation strategies. We studied a tar oil contaminated soil with weak grass vegetation at a former manufactured gas plant site in Germany. Despite of the apparent toxicity (the soil contained up to 120 g kg<sup>-1</sup> petroleum hydrocarbons, 26 g kg<sup>-1</sup> toxic metals, and 100 mg kg<sup>-1</sup> polycyclic aromatic hydrocarbons), the contaminated layers have 3-5 times as much cell counts as an uncontaminated control soil nearby. To test, if the geometry of the pore space provides favourable living space for microorganisms, we applied scanning electron microscopy to the thin sections and calculated on sets of 15 images per layer three specific Minkowski functionals, connected to soil total porosity, interface, and hydraulic parameters.</p><p>Our investigation showed that the uncontaminated control soil has a relatively low porosity of 15-20 %, of which 50-70 % is comprised of small (< 15 µm) pores. These pores are poorly connected and show high distances between them (mean distance to the next pore 10 µm). The dominating habitats in the control soil are therefore created by small pores. They provide good protection from predators and desiccation, but input of dissolved organic C and removal of metabolic products are diffusion limited. Coarser pores (>15 µm) provide less space (< 50 % of total porosity) and solid surface area (< 20 %), are prone to desiccation and offer less protection from predators. However, they serve as preferential flow paths for the soil solution (input of nutrients) and are well aerated, therefore we expect the microbial activity in them to appear in “hot moments”, i.e. after rain events.</p><p>All layers of the contaminated profile have higher porosities (20-70 %) than the control. Coarse pores comprise 83-90 % of total pore area and create 34-52 % of total interface. Pores are also more connected and tortuous than in the control soil, which implies a better aeration and circulation of soil solution. The loops of pore channels may retain soil solution and be therefore preferably populated with microorganisms. The small (< 15 µm) pores comprise less than 17 % of total porosity but represent a substantial proportion of the interface (48-66 % vs 82-91 % in control). In the uppermost layer of the contaminated profile, such pores occur in plant residues, are close to the largest pores (mean distance to the next pore 4 µm) and therefore, along with good protection, are supplied with air, water, and non-tar C. In the middle of the profile, the small pores, presumably constantly filled with water, are located within dense tar pieces remote from the neighbouring pores (mean distance to the next pore 22 µm), and therefore, with hindered aeration and no supply of non-tar C, may create anaerobic domains of tar attenuation.</p><p>Our results show that the contaminated soil offers more favourable conditions for microorganisms than the control soil, probably because the hydrocarbons provide suitable energy and nutrition sources and a beneficial pore space geometry.</p>

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