S. E. M. Observations of Limestone Pore Space Replicas

1974 ◽  
Vol 32 ◽  
pp. 462-463
Author(s):  
J. W. Becher
Keyword(s):  
Size Distribution ◽  
Carbonate Rocks ◽  
Pore Space ◽  
Rock Material ◽  
Pore Geometry ◽  
Hydrocarbon Migration ◽  
Mineral Material ◽  
Major Parameter ◽  
Wet Rocks ◽  
Actual Rock

Pore geometry in carbonate rocks is of interest to petroleum geologists because it reflects the complex diagenetic changes that may create or destroy porosity. The size distribution of pore throats (restrictions in the continuous maze of pore channels) is a major parameter controlling hydrocarbon migration through water-wet rocks.Pore space replicas (plastic casts of pore space with the mineral material removed) have decided advantages over actual rock material for pore space observations. The replication of a limestone with 10 percent porosity will yield a plastic replica with 90 percent porosity.

4D petroelastic modeling based on a presalt well

2020 ◽  
Vol 8 (3) ◽  
pp. T639-T649
Author(s):  
E. P. A. Silva ◽  
A. Davólio ◽  
M. S. Santos ◽  
D. J. Schiozer
Keyword(s):  
Feasibility Study ◽  
Acoustic Impedance ◽  
Carbonate Rocks ◽  
Seismic Analysis ◽  
Pore Space ◽  
Feasibility Studies ◽  
Time Lapse ◽  
Pore Geometry ◽  
Initial Discovery ◽  
Payne Model

After their initial discovery in 2006, followed by an accumulated production of over 2 billion barrels of oil equivalent, the presalt carbonate reservoirs of offshore Brazil are now candidates for time-lapse seismic analysis. Therefore, we have conducted a 4D feasibility study in a Brazilian presalt reservoir well, which is composed of two types of carbonate rocks: microbialite and coquina. We evaluated two petroelastic models to obtain the acoustic impedance (AI) and shear impedance (SI) needed to estimate potential time-lapse differences ([Formula: see text], [Formula: see text], and [Formula: see text]). For this, we used the Gassmann and Xu-Payne models, in which the latter considers the pore geometry of the rock in its equations. Our analysis of both models shows that changes in pressure and saturation are very similar, and we can conclude that, despite being a carbonate, the application of Gassmann’s model is sufficient for the 4D feasibility studies conducted in the deemed reservoir because it does not require pore space geometry parameters, as does the Xu-Payne model. The analysis of the time-lapse attributes provided us with a greater comprehension of the 4D scenarios modeled, some of which presented detectability of changes in the microbialite and coquina.

scholarly journals The Validation Process of the Method of Balancing Gas Contained in the Pore Space of Rocks via Rock Comminution

2018 ◽  
Author(s):  
Mateusz Kudasik ◽  
Anna Pajdak ◽  
Norbert Skoczylas
Keyword(s):  
Size Distribution ◽  
Pore Volume ◽  
Pore Space ◽  
Sem Analysis ◽  
Rock Material ◽  
Grinding Process ◽  
Validation Process ◽  
Research Material ◽  
Granulometric Analysis ◽  
Comminution Process

The article discusses the validation process of a certain method of balancing gas contained in the pore space of rocks. The validation was based upon juxtaposition of the examination of rocks' porosity and the effects of comminution in terms of assessing the possibility of opening the pore space. The tests were carried out for six dolomite samples taken from different areas of the 'Polkowice-Sieroszowice’ copper mine in Poland. Before the rock material was ground, it was examined using the porosimetric method and subsequently subjected to the SEM analysis. After grinding, the research material was subjected to the granulometric analysis. Prior to the grinding process, the rocks' porosity fell in the range of 0.3-14.8%, while the volume of the open pores was included in the 0.01-0.06 cm3/g range. The research material was also characterized by inhomogeneous distribution of the pore volume. The grinding process was performed using an original device – the GPR analyzer. The ground samples were characterized by similar particle size distribution and mean diameters D_3.2 of about 4.0-4.5 µm. The SEM analysis revealed pores of various size and shape on the surface of the rock cores, while at the same time demonstrating lack of pores following the grinding process. The grain size distribution curves were compared with the cumulative pore volume curves of the cores before grinding. The resulting intersection points of both curves were seen as testifying to the presence of openings in the rock pores and release of the accumulated gas. The opening percentage of the pore space was associated with the coordinates of the curves' intersections. In order to confirm the argument put forward in this paper – i.e. that comminution of a rock to grains of a size comparable with the size of the rock's pores results in the release of gas contained in the pore space – the amount of gas released as a result of the comminution process was studied. The results of gas balancing demonstrated that the pore space of the investigated dolomites was filled with gas in amounts from 3.19 cm3/kg to 45.86 cm3/kg. The obtained results of the rock material comminution to grains comparable – in terms of size – to the size of the pores of investigated rocks, along with asserting the presence of gas in the pore space of the studied dolomites, were regarded as a proof that the method of balancing gas in rocks via rock comminution is correct.

Trapping patterns during capillary displacements in disordered media

2022 ◽  
Vol 933 ◽  
Author(s):  
Fanli Liu ◽  
Moran Wang
Keyword(s):  
Numerical Simulations ◽  
Pore Size Distribution ◽  
Pore Size ◽  
Size Distribution ◽  
Disordered Media ◽  
Pore Geometry ◽  
Control Parameters ◽  
Pore Throat ◽  
The Impact ◽  
Theoretical Analyses

We investigate the impact of wettability distribution, pore size distribution and pore geometry on the statistical behaviour of trapping in pore-throat networks during capillary displacement. Through theoretical analyses and numerical simulations, we propose and prove that the trapping patterns, defined as the percentage and distribution of trapped elements, are determined by four dimensionless control parameters. The range of all possible trapping patterns and how the patterns are dependent on the four parameters are obtained. The results help us to understand the impact of wettability and structure on trapping behaviour in disordered media.

scholarly journals Modelling surface NMR spin-echo experiments in a heterogeneous B1 field

2019 ◽  
Vol 219 (2) ◽  
pp. 1395-1404
Author(s):  
Denys Grombacher
Keyword(s):  
Pore Space ◽  
Spin Echo ◽  
Petroleum Industry ◽  
Bloch Equation ◽  
Transverse Magnetization ◽  
Subsurface Water ◽  
Great Promise ◽  
Pore Geometry ◽  
Analytic Expression ◽  
B1 Field

SUMMARY Surface nuclear magnetic resonance (NMR) measurements show great promise for characterization of subsurface water content, pore-sizes and permeability. The link between surface NMR and pore-size/permeability is founded in the connection between the NMR signal's time dependence and the geometry of the pore-space. To strengthen links between the NMR signal and pore-geometry multipulse surface NMR sequences have been developed to estimate the parameter T2, which carries a strong link to pore-geometry and has formed the basis for NMR-based permeability estimation in the petroleum industry for decades. Producing reliable subsurface characterizations from multipulse surface NMR measurements that measure T2 requires that the forward model is able to accurately predict the transverse magnetization at the time when the measurement occurs. Traditional surface NMR T2 forward models employ an analytic expression for the transverse magnetization, an expression developed in the context of laboratory NMR experiments conducted under conditions significantly different from surface NMR and which require several assumptions to simplify the underlying Bloch equation. To investigate the reliability of this analytic expression under surface NMR conditions, a synthetic comparison is performed where the analytic expression is contrasted against the transverse magnetization predicted from a solution of the full-Bloch equation without the same simplifying assumptions and which can appropriately weight heterogeneity in the applied and background magnetic fields. The comparison shows that the analytic expression breaks down in a range of conditions typical to surface NMR measurements.

Velocity–porosity–mineralogy trends in chalk and consolidated carbonate rocks

2019 ◽  
Vol 219 (1) ◽  
pp. 662-671 ◽  
Author(s):  
Jack Dvorkin ◽  
Abrar Alabbad
Keyword(s):  
Carbonate Rocks ◽  
Pore Space ◽  
Rock Physics ◽  
Elastic Wave Velocity ◽  
Velocity Versus ◽  
Shear Moduli ◽  
Diagenetic Alteration ◽  
Medium Porosity ◽  
Physics Model ◽  
Rock Physics Model

SUMMARY Published laboratory elastic-wave velocity versus porosity data in carbonate rocks exhibit significant scatter even at a fixed mineralogy. This scatter is usually attributed to the strong variability in the rock-frame or pore-space geometry, which, in turn, is driven by the richness and complexity of diagenetic alteration in these very reactive sediments. Yet, by examining wireline data from oil-bearing high-to-medium porosity chalk deposits, we find surprisingly tight velocity–porosity trends. Moreover, these trends are continued into the low-porosity domain by data from a location thousands of miles away from the chalk field. This congruence implies a universality of diagenetic trends, at least in the massive deposits under examination. We also find that the elastic bulk and shear moduli of the pure-calcite end member are somewhat smaller than such values reported in the literature. Using the end-member elastic constants relevant to the data under examination, we establish a theoretical rock physics model to match and generalize these data.

scholarly journals Influence of the Pore Geometry on the Micropore Size Distribution Function of Active Carbons

1997 ◽  
Vol 15 (8) ◽  
pp. 571-581 ◽  
Author(s):  
J. Choma ◽  
M. Jaroniec
Keyword(s):  
Distribution Function ◽  
Size Distribution ◽  
Density Functional ◽  
Simple Procedure ◽  
Size Distribution Function ◽  
Pore Geometry ◽  
Geometrical Shape ◽  
Active Carbons ◽  
Micropore Size Distribution ◽  
Micropore Size

A simple procedure for the evaluation of the micropore size distribution function of active carbons from the experimental adsorption isotherm of a single gas is discussed. In this method, the adsorption potential distribution and the dependencies of this potential on the micropore size for three different models, i.e. slit-like, cylindrical and spherical, are utilized. It was shown that the geometrical shape of pores may have a substantial influence on the micropore size distribution. While the micropore size distributions calculated assuming slit-like and cylindrical pore geometries are similar, spherical pore geometry leads to a substantially different distribution. A qualitative agreement was found between the micropore size distribution obtained by the current procedure, which is equivalent to the Horvath–Kawazoe method, and that evaluated by the density functional theory (DFT) method.

Sign in / Sign up

Export Citation Format

Share Document