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.

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.

Integrated operations program with Statoil

2011 ◽  
Vol 51 (2) ◽  
pp. 682
Author(s):  
David Haake
Keyword(s):  
Research And Development ◽  
Petroleum Industry ◽  
Great Promise ◽  
Active Member ◽  
Work Processes ◽  
Time Data ◽  
Business Organisation ◽  
Industry Standards ◽  
Offshore Industry ◽  
Integrated Operations

Several years ago, IBM established its Smarter Planet vision: to bring a new level of intelligence to how the world works—to how every person, business, organisation, government, natural system, and man-made system interacts. Mr Haake will present a case study from our collaboration with Statoil on integrated operations. Statoil defines integrated operations (IO) as: collaboration across disciplines, companies, organisational and geographical boundaries—made possible by real-time data and new work processes—to reach safer and better decisions faster. To help identify the methods, technologies and work processes necessary to integrate its operations, Statoil appointed a research and development consortium consisting of ABB, IBM, SKF and Aker Kvaerner. The Statoil TAIL IO project was aimed at improving operations at fields approaching the end of their life-spans—the stage where production rate is declining, the facilities are aging, and the cost of operation is high. The result is a set of integrated operations solutions based on industry standards that offer great promise. “Our efforts to bring more integration and collaboration to our production processes are critical to the future of the offshore industry. IBM has shown a strong commitment to helping us achieve this goal.”—Adolfo Henriquez, head of Integrated Operations, Statoil. IBM Research, is the world’s largest private research institution. The IBM annual research and development budget is nearly $6 Billion. IBM is also an active member and participant in the development and leadership of multiple petroleum industry standards bodies: Mimosa and Open Operations & Maintenance Integrated Operations of the High North (IOHN) Energistics, coordinating WITSML and PRODML.

Pore geometry effects on elastic properties of Opalinus Clay

Geophysics ◽  
2016 ◽  
Vol 81 (5) ◽  
pp. D543-D551 ◽  
Author(s):  
Lukas M. Keller
Keyword(s):  
Elastic Properties ◽  
Volume Fraction ◽  
Water Saturation ◽  
Pore Space ◽  
Ion Beam ◽  
Evaluation Process ◽  
Preferred Orientation ◽  
Opalinus Clay ◽  
Pore Geometry ◽  
Anisotropy Parameters

Regarding the storage of nuclear waste within clay rock formations requires fundamental understanding of elastic properties of this rock type with regard to the risk evaluation process. The influence of the pore geometry on elastic properties of Opalinus Clay is studied on the basis of realistic pore microstructure, which is reconstructed from image data acquired by focused ion beam nanotomography. These microstructures are used as input pore geometries for linear elastic finite-element modeling to determine Thomsen’s [Formula: see text], [Formula: see text], and [Formula: see text] anisotropy parameters and the effective elastic moduli related to the porous material. The presence of fully drained intergranular pores substantially increases the values of [Formula: see text] and [Formula: see text]. For the investigated sample with an expected porosity of approximately 10 vol.%, the anisotropic pore space contributes similarly to the anisotropy parameters when compared with the contribution related to the preferred orientation of minerals. On the other hand, if the pore space is undrained, the effect of pores is smaller and the anisotropy is largely controlled by the preferred orientation of minerals. It is revealed that the value of [Formula: see text] is most sensitive to changes in water saturation. In case water is drained from the pores, the vertical Young’s modulus [Formula: see text] reduces significantly more when compared with the horizontal modulus [Formula: see text]. Presuming that the drainable porosity corresponds to a volume fraction of 10 vol.%, [Formula: see text] reduces by approximately 15%–20%. The effect of drainage is even more pronounced for the Poisson’s ratios, whereas the shear moduli are not much affected by drainage.

The Role of Terzaghi Effective Stress in Linearly Elastic Deformation

1983 ◽  
Vol 105 (4) ◽  
pp. 509-511 ◽  
Author(s):  
M. M. Carroll ◽  
N. Katsube
Keyword(s):  
Elastic Deformation ◽  
Effective Stress ◽  
Linear Elasticity ◽  
Simple Form ◽  
Pore Space ◽  
Elastic Solid ◽  
Solid Matrix ◽  
Pore Geometry ◽  
Average Strain

It has been shown that the overall strain of a fluid-filled porous elastic solid is not governed by the Terzaghi effective stress law. We show, in the context of anisotropic linear elasticity, that the overall strain may be resolved into a component which is the average strain of the solid matrix and a component due to change in relative pore geometry, and that the latter is determined by the Terzaghi effective stress. This leads to a simple form of the response laws and, in particular, to effective stress laws for overall strain (obtained previously) and for strain of the pore space.

scholarly journals Mechanisms of consistently disconnected soil water pools over (pore)space and time

2019 ◽  
Author(s):  
Matthias Sprenger ◽  
Pilar Llorens ◽  
Carles Cayuela ◽  
Francesc Gallart ◽  
Jérôme Latron
Keyword(s):  
Soil Water ◽  
Soil Depth ◽  
Stream Water ◽  
Pore Space ◽  
Bound Water ◽  
Subsurface Water ◽  
Data Set ◽  
Silty Loam ◽  
Scots Pine Forest ◽  
Soil Pores

Abstract. Storage and release of water in the soils is critical for sustaining plant transpiration and groundwater recharge. However, the subsurface mixing of water available for plants or quickly flowing to streams and groundwater is not yet understood. Moreover, while water infiltrating into soils was shown to bypass older pore water, the mechanisms leading to a separation between water routed to the streams and water held tightly in smaller pores are unclear. Here we present an extensive data set, for which we sampled fortnightly the isotopic composition (2H and 18O) of mobile and bulk soil water in parallel with groundwater, stream water and rainfall in the Mediterranean long-term research catchment, Vallcebre, in Spain. The data revealed that mobile and tightly bound water of a silty loam soil in a Scots pine forest do not mix, but they constitute two separate subsurface water pools; despite intense rainfall events leading to high soil wetness. We show that the isotopic compartmentation results from rewetting of small soil pores with isotopically depleted winter/spring rain. Thus, stable isotopes, and therefore water residence times too, do not only vary across soil depth, but also across soil pores. Our findings have important implications for stable isotope applications in ecohydrological studies assessing water uptake by plants or process realism of hydrological models, as the observed processes are currently rarely implemented in the simulation of water partitioning into evapotranspiration and recharge in the critical zone.

scholarly journals Localization in Flow of Non-Newtonian Fluids Through Disordered Porous Media

2021 ◽  
Vol 9 ◽  
Author(s):  
H. J. Seybold ◽  
U. Eberhard ◽  
E. Secchi ◽  
R. L. C. Cisne ◽  
J. Jiménez-Martínez ◽  
...  
Keyword(s):  
Porous Media ◽  
Spatial Distribution ◽  
Pore Space ◽  
Pore Geometry ◽  
Flow Conditions ◽  
Flow Localization ◽  
Chemical Reactors ◽  
Nonlinear Rheology ◽  
Constitutive Properties ◽  
Disordered Porous Media

We combine results of high-resolution microfluidic experiments with extensive numerical simulations to show how the flow patterns inside a “swiss-cheese” type of pore geometry can be systematically controlled through the intrinsic rheological properties of the fluid. Precisely, our analysis reveals that the velocity field in the interstitial pore space tends to display enhanced channeling under certain flow conditions. This observed flow “localization”, quantified by the spatial distribution of kinetic energy, can then be explained in terms of the strong interplay between the disordered geometry of the pore space and the nonlinear rheology of the fluid. Our results disclose the possibility that the constitutive properties of the fluid can enhance the performance of chemical reactors and chromatographic devices through control of the channeling patterns inside disordered porous media.

Incorporating pore geometry and fluid pressure communication into modeling the elastic behavior of porous rocks

Geophysics ◽  
1997 ◽  
Vol 62 (1) ◽  
pp. 106-117 ◽  
Author(s):  
Anthony L. Endres ◽  
Rosemary J. Knight
Keyword(s):  
Closed System ◽  
Elastic Moduli ◽  
Pore Space ◽  
Fluid Pressure ◽  
Continuous Distribution ◽  
Elastic Behavior ◽  
Pore Geometry ◽  
Porous Rocks ◽  
Low Frequencies ◽  
Poroelastic Theory

Inclusion‐based formulations allow an explicit description of pore geometry by viewing porous rocks as a solid matrix with embedded inclusions representing individual pores. The assumption commonly used in these formulations that there is no fluid pressure communication between pores is reasonable for liquid‐filled rocks measured at high frequencies; however, complete fluid pressure communication should occur throughout the pore space at low frequencies. A generalized framework is presented for incorporating complete fluid pressure communication into inclusion‐based formulations, permitting elastic behavior of porous rocks at high and low frequencies to be described in terms of a single model. This study extends previous work by describing the pore space in terms of a continuous distribution of shapes and allowing different forms of inclusion interactions to be specified. The effects of fluid pressure communication on the elastic moduli of porous media are explored by using simple models and are found to consist of two fundamental elements. One is associated with the cubical dilatation and governs the effective bulk modulus. Its magnitude is a function of the range of pore shapes present. The other is due to the extensional part of the deviatoric strain components and affects the effective shear modulus. This element is dependent on pore orientation, as well as pore shape. Using sandstone and granite models, an inclusion‐based formulation shows that large differences between high‐ and low‐frequency elastic moduli can occur for porous rocks. An analysis of experimental elastic wave velocity data reveals behavior similar to that predicted by the models. Quantities analogous to the open and closed system moduli of Gassmann‐Biot poroelastic theory are defined in terms of inclusion‐based formulations that incorporate complete fluid pressure communication. It was found that the poroelastic relationships between the open and closed system moduli are replicated by a large class of inclusion‐based formulations. This connection permits explicit incorporation of pore geometry information into the otherwise empirically determined macroscopic parameters of the Gassmann‐Biot poroelastic theory.

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.

Cryo-SEM of liquid-bearing rock

1988 ◽  
Vol 46 ◽  
pp. 104-105 ◽  
Author(s):  
E. Sutanto
Keyword(s):  
Pore Space ◽  
Contact Angles ◽  
Solid Surfaces ◽  
Fluid Distribution ◽  
Pore Geometry ◽  
Flow Through Porous Media ◽  
Flow Through ◽  
Grain Surface ◽  
Wetting Fluid ◽  
Local Nature

Scanning electron microscopy has been used to examine microstructure of dry soils, sedimentary rocks and other porous materials for three decades. There are many studies of sand grain surface texture, pore morphology, and clay swelling. However, pore geometry and surface topography are only part of the story of how two or more fluids flow through porous media, whether they be unconsolidated or consolidated. The other part is how the fluids distribute in the pore space. Fluid distribution in pore space is largely governed by relative wettability of pore walls. Wetting fluid tends to reside on walls as a thin film and to occupy small pores totally, whereas nonwetting fluid tends to occupy the center of larger pores. Which fluid is more strongly wetting depends on the local nature of the wall. Contact angles indicate wettability of planar, homogeneous solid surfaces, but roughness and compositional heterogeneity, which seem to be common in sedimentary rock, complicate matters.

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