다중혈관 관상동맥 환자에서 y-문합을 이용하여 양쪽 내흉동맥만을 사용한 우회술의 조기 성적

Preface 1. Basic tools 2. Elasticity and Hooke's law 3. Seismic wave propagation 4. Effective media 5. Granular media 6. Fluid effects on wave propagation 7. Empirical relations 8. Flow and diffusion 9. Electrical properties Appendices.

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The Rock Physics Handbook: Tools for Seismic Analysis of Porous Media

Responding to the latest developments in rock physics research, this popular reference book has been thoroughly updated while retaining its comprehensive coverage of the fundamental theory, concepts, and laboratory results. It brings together the vast literature from the field to address the relationships between geophysical observations and the underlying physical properties of Earth materials - including water, hydrocarbons, gases, minerals, rocks, ice, magma and methane hydrates. This third edition includes expanded coverage of topics such as effective medium models, viscoelasticity, attenuation, anisotropy, electrical-elastic cross relations, and highlights applications in unconventional reservoirs. Appendices have been enhanced with new materials and properties, while worked examples (supplemented by online datasets and MATLAB® codes) enable readers to implement the workflows and models in practice. This significantly revised edition will continue to be the go-to reference for students and researchers interested in rock physics, near-surface geophysics, seismology, and professionals in the oil and gas industries.

The Rock Physics Handbook

Pore structure characterization of North American shale gas reservoirs using USANS/SANS, gas adsorption, and mercury intrusion

One of the biggest challenges in estimating the elastic, transport and storage properties of shales has been a lack of understanding of their complete pore structure. The shale matrix is predominantly composed of micropores (pores less than 2 nm diameter) and mesopores (pores with 2–50 nm diameter). These small pores in the shale matrix are mainly associated with clay minerals and organic matter and comprehending the controls of these clays and organic matter on the pore-size distribution is critical to understand the shale pore network. Historically, mercury intrusion techniques are used for pore-size analysis of conventional reservoirs. However, for unconventional shale reservoirs, very high pressures (> 414 MPa (60 000 psi)) would be required for mercury to access the full pore structure, which has potential pitfalls. Current instrumental limitations do not allow reliable measurement of significant portions of the total pore volume in shales. Nitrogen gas-adsorption techniques can be used to
characterize materials dominated by micro- and mesopores (2–50 nm). A limitation
of this technique is that it fails to measure large pores (diameter >200 nm). We use a nitrogen gas-adsorption technique to study the micro- and mesopores in shales and clays and compare the results from conventional mercury porosimetry techniques. Our results on pure clay minerals and natural shales show that (i) they have a multiscale pore structure at different dimensions (ii) fine mesopores, with a characteristic 3 nm pore size obtained with N2 gas-adsorption are associated with an illite-smectite group of clays but not with kaolinite; (iii) compaction results in a decrease of pore volume and a reduction of pore size in the ‘inter-aggregate’ macropores of the illitesmectite clays while the fine ‘intra-tachoid’ mesopores are shielded from compaction; (iv) for natural shales, mineralogy controls the pore-size distributions for shales and the presence of micropores and fine mesopores in natural shales can be correlated
with the dominance of the illite-smectite type of clays in the rock. Our assessment of incompressible 3 nm sized pores associated with illite-smectite clays provides an important building block for their mineral modulus.

Specific surface area and pore‐size distribution in clays and shales

Nano-scale texture and porosity of organic matter and clay minerals in organic-rich mudrocks

The presence of clay minerals can alter the elastic behaviour of rocks significantly. Although clay minerals are common in sedimentary formations and seismic measurements are our main tools for studying subsurface lithologies, measurements of elastic properties of clay minerals have proven difficult. Theoretical values for the bulk modulus of clay are reported between 20 and 50 GPa. The only published experimental measurement of Young's modulus in a clay mineral using atomic force acoustic microscopy (AFAM) gave a much lower value of 6.2 GPa. This study has concentrated on using independent experimental methods to measure the elastic moduli of clay minerals as functions of pressure and saturation. First, ultrasonic P- and S-wave velocities were measured as functions of hydrostatic pressure in cold-pressed clay aggregates with porosity and grain density ranging from 4 to 43 per cent and 2.13 to 2.83 g cm - 3 , respectively. In the second experiment, P- and S-wave velocities in clay powders were measured under uniaxial stresses compaction. In the third experiment, P-wave velocity and attenuation in a kaolinite-water suspension with clay concentrations between 0 and 60 per cent were measured at ambient conditions. Our elastic moduli measurements of kaolinite, montmorillonite and smectite are consistent for all experiments and with reported AFAM measurements on a nanometre scale. The bulk modulus values of the solid clay phase (K s ) lie between 6 and 12 GPa and shear (μ s ) modulus values vary between 4 and 6 GPa. A comparison is made between the accuracy of velocity prediction in shaley sandstones and clay-water and clay-sand mixtures using the values measured in this study and those from theoretical models. Using K s = 12 GPa and μ s = 6 GPa from this study, the models give a much better prediction both of experimental velocity reduction due to increase in clay content in sandstones and velocity measurements in a kaolinite-water suspension.

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Elastic properties of dry clay mineral aggregates, suspensions and sandstones

We offer an effective medium model for the elastic moduli of high-porosity ocean-bottom sediments. The elastic constants of the dry-sediment frame depend on porosity, elastic moduli of the solid phase, and effective pressure. The model connects two end points in the elastic-modulus-porosity plane: the Hertz-Mindlin modulus of a dense elastic sphere pack at critical porosity; and zero at 100% porosity. The elastic moduli of saturated sediment are calculated from those of the dry frame using Gassmann's equation. Unlike the suspension model, our model assigns non-zero elastic constants to the dry-sediment frame and can predict the shear-wave velocity. Unlike various modifications of the travel-time-average equation, it is first-principle-based and contains only physical parameters. We justify this model by matching sonic data in shallow marine sediments and in an ODP well.

https://agupubs.onlinelibrary.wiley.com/doi/pdf/10.1029/1999GL900332

Elasticity of marine sediments: Rock physics modeling

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

Manika Prasad

Papers

Specific surface area and pore‐size distribution in clays and shales

Nano-scale texture and porosity of organic matter and clay minerals in organic-rich mudrocks

Elastic properties of dry clay mineral aggregates, suspensions and sandstones

Elasticity of marine sediments: Rock physics modeling

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