Experimental Study on Petrophysical Properties as a Tool to Identify Pore Fluids in Tight-Rock Reservoirs

The petrophysical properties can be proper indicators to identify oil and gas reservoirs, since the pore fluids have significant effects on the wave response. We have performed ultrasonic measurements on two sets of tight siltstones and dolomites at partial saturation. P- and S-wave velocities are obtained by the pulse transmission technique, while attenuation is calculated using the centroid-frequency shift and spectral-ratio methods. The fluid sensitivities of different properties (i.e., P- and S-wave velocities, impedances and attenuation, Poisson's ratio, density, and their combinations) are quantitatively analyzed by considering the data distribution, based on the crossplot technique. The result shows that the properties (P- to S-wave velocity and attenuation ratios, Poisson's ratio, and first to second Lamé constant ratio) with high fluid-sensitivity indicators successfully distinguish gas from oil and water, unlike oil from water. Moreover, siltstones and dolomites can be identified on the basis of data distribution areas. Ultrasonic rock-physics templates of the P- to S-wave velocity ratio vs. the product of first Lamé constant with density obtained with a poroelastic model, considering the structural heterogeneity and patchy saturation, are used to predict the saturation and porosity, which are in good agreement with the experimental data at different porosity ranges.

Modeling and simulation of mechanical and physical properties of Barium orthotitanate (Ba2TiO4) composite by Materials Studio ( MS)

This research including a study of mechanical ,physical properties (band structure, density of states) and the elasticity constants of the Barium Ortho titanate by using Materials studio software. The calculations were based on the generalized gradient approximation (GGA) by linear method. The calculated equilibrium lattice constants of monoclinic barium orthotitanate were: a = 0.612nm, b = 0.77nm, c = 1.05nm,calculated bulk modulus =42.3021 GPa, young modulus= 40.29 GPa, share modulus = 15.97 GPa, lame constant (λ)= 142.56 GPa ,and energy band gap=3.435eV which is indirect band gap and the composite is insulator and the electronic properties where be calculated in first Brillion zone. According the mechanical stability conditions the composite is stable mechanically. These results were calculated by Materials studio software.

A Robust Weak Galerkin Finite Element Method for Linear Elasticity with Strong Symmetric Stresses

This paper proposes and analyzes a weak Galerkin (WG) finite element method with strong symmetric stresses for two- and three-dimensional linear elasticity problems on conforming or nonconforming polygon/polyhedral meshes. The WG method uses piecewise-polynomial approximations of degreesk(${\geq 1}$) for the stress,${k+1}$for the displacement, andkfor the displacement trace on the inter-element boundaries. It is shown to be equivalent to a hybridizable discontinuous Galerkin (HDG) finite element scheme. We show that the WG methods are robust in the sense that the derived a priori error estimates are optimal and uniform with respect to the Lamé constant λ. Numerical experiments confirm the theoretical results.

A Note on the Effective Lame´ Constants of Polycrystalline Aggregates of Cubic Crystals

It is well known that the Voigt and Reuss estimates of the effective shear modulus of a polycrystalline aggregate of cubic crystals are, respectively, the upper and lower bounds for this constant (μR ≤ μ ≤ μV). It is pointed out in this note that the opposite is true for the Lame´ constant λ (λV ≤ λ ≤ λR).