Applications and Study on Organophosphate Acids (Salts) for Oil Well Cement Retarder

AbstractA synthetic cement retarder SDH-2 which provides excellent retardation and compressive strength development has been synthesized to be used in deep oil well cementation. The response properties, temperature-resistant and anti-salt properties, additive distribution and compressive strength have been evaluated. It is showed SDH-2 has good retarding ability to oil well cement slurries at 40 to 204 ℃。It is compatible with dispersant, fluid loss additive and other additives to grade G oilwell cement of various manufactures and can be used in cementing process in the temperature of various depths in oil well

Well-posedness and regularity of the Darcy-Boussinesq system in layered porous media

We investigate the Darcy-Boussinesq model for convection in layered porous media. In particular, we establish the well-posedness of the model in two and three spatial dimension, and derive the regularity of the solutions in a novel piecewise H2 space

Analysis and Finite Element Approximation of a Coupled, Continuum Pipe-Flow/Darcy Model for Flow in Porous Media with Embedded Conduits

We consider the continuum Darcy/pipe flow model for flows in a porous matrix containing embedded conduits; such coupled flows are present in, e.g., karst aquifers. the mathematical well-posedness of the coupled problem as well as convergence rates of finite element approximation are established in the two-dimensional case. Computational results are also provided. © 2010 Wiley Periodicals, Inc

Decoupling the Stationary Navier-Stokes-Darcy System with the Beavers-Joseph-Saffman Interface Condition

This paper proposes a domain decomposition method for the coupled stationary Navier-Stokes and Darcy equations with the Beavers-Joseph-Saffman interface condition in order to improve the efficiency of the finite element method. The physical interface conditions are directly utilized to construct the boundary conditions on the interface and then decouple the Navier-Stokes and Darcy equations. Newton iteration will be used to deal with the nonlinear systems. Numerical results are presented to illustrate the features of the proposed method

Proton incorporations and superconductivity in a cobalt oxyhydrate

We report the evidence of proton incorporations in a newly-discovered cobalt oxyhydrate superconductor. During the hydration process for Na$_{0.32}$CoO$_{2}$ by the direct reaction with water liquid, it was shown that substantial NaOH was gradually liberated, indicating that H$^{+}$ is incorporated into the hydrated compound. Combined with the thermogravimetric analysis, the chemical composition of the typical sample is Na$_{0.22}$H$_{0.1}$CoO$_{2}\cdot 0.85$H$_{2}$O, which shows bulk superconductivity at 4.4 K.Comment: 9 pages, 4 figure