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The present paper presents a fully coupled thermo-hydro-mechanical-chemical (THMC) model for chemically active deformable porous media (such as clay or clay-like shale) under local thermal and chemical equilibrium (LTE and LCE) conditions. The proposed model is developed by combining the phenomenological method and the new entropy production derived based on the non-equilibrium thermodynamics. Our proposed THMC model introduces the following new coupled terms: (1) ultrafiltration effects in the solute flux equation, (2) thermal filtration and Dufour effects into the heat flux expression, and (3) strain, pressure, and solute mass-fraction in the thermal diffusion equation. This model also introduces the influence of bound water that occupies the interlayer space of clay platelets and governs the chemical and mechanical responses as the solid part of porous media. We derive semi-analytical solutions for the specific engineering application of stability of an inclined wellbore in a chemically active clay-like shale formation during petroleum drilling, considering the fully coupled porochemothermoelastic effects under the plane strain assumption. The wellbore loading is decomposed into axisymmetric and deviatoric cases. The time-dependent field variables including displacements, pore pressures, stresses, solute fraction, and temperatures are obtained by performing the inversion of the Laplace transforms. Based on the newly developed semi-analytical porochemothermoelastic solutions, several analyses are conducted to evaluate the influence of the newly introduced terms in the THMC model on pore pressures and stresses around a horizontal wellbore in a shale formation; and on time-dependent failure behavior, including shear failure and tensile fracturing. Results show that the significance of the newly introduced ultrafiltration, thermal filtration, and Dufour effects on induced pore pressure not only depends on the permeability, thermo-osmotic, and thermal diffusion coefficients, but also on the in-situ pressure, temperature, and chemical gradients. We suggest that the drilling engineers consider the time-dependent and location-dependent characteristics of borehole failure that depend on the thermo-hydro-mechanical-chemical process and appropriately design the mud weight required to ensure wellbore stability. [ABSTRACT FROM AUTHOR]

Abstract: As an efficient catalyst for asymmetric transfer hydrogenation reaction (ATH reaction) of α,β-unsaturated ketones, Rh-Cp∗–TsDPEN (Cp∗ =1,2,3,4,5-pentamethylcyclopenta-1,3-diene, TsDPEN= N-(p-toluenesulfonyl)-1,2-diphenyl- ethylenediamine) shows high chemoselectivity on Ce:glyph name="dbnd" />C reduction. In our method, both Ce:glyph name="dbnd" />C bonds in a variety of chromenone derivatives were reduced efficiently in aqueous media, resulting in at least 98% ee and up to 99% yields in a convenient way without further purification. The product was a useful intermediate for deriving chiral chroman-4-amine, which was reported as an effective agent against hypotension and inflammatory pain by inhibiting human bradykinin B1 receptor. [Copyright &y& Elsevier]

Long-term oil and gas exploitation in reservoir will lead to pore pressure depletion. The pore pressure depletion will result in changes of horizontal in-situ stresses both in reservoirs and caprock formations. Using the geophysics logging data, the magnitude and orientation changes of horizontal stresses in caprock and reservoir are studied. Furthermore, the borehole stability can be affected by in-situ stresses changes. To address this issue, the dehydration from caprock to reservoir and roof effect of caprock are performed. Based on that, the influence scope and magnitude of horizontal stresses reduction in caprock above the depleted reservoirs are estimated. The effects of development on borehole stability in both reservoir and caprock are studied step by step with the above geomechanical model.

Wellbore instability in oil and gas drilling is resulted from both mechanical and chemical factors. Hydration is produced in shale formation owing to the influence of the chemical property of drilling fluid. A new experimental method to measure diffusion coefficient of shale hydration is given, and the calculation method of experimental results is introduced. The diffusion coefficient of shale hydration is measured with the downhole temperature and pressure condition, then the penetration migrate law of drilling fluid filtrate around the wellbore is calculated. Furthermore, the changing rules of shale mechanical properties affected by hydration and water absorption are studied through experiments. The relationships between shale mechanical parameters and the water content are established. The wellbore stability model chemical-mechanical coupling is obtained based on the experimental results. Under the action of drilling fluid, hydration makes the shale formation softened and produced the swelling strain after drilling. This will lead to the collapse pressure increases after drilling. The study results provide a reference for studying hydration collapse period of shale.

Although a notable feature of Noyori's Ru-TsDPEN complex is that the transfer hydrogenation reaction is highly chemoselective for the C=O functional group and tolerant of alkenes, our early report indicated that the chemoselectivity could be switched from C=O to C=C bonds in the transfer hydrogenation of activated alpha,beta-unsaturated ketones. Now we have found that a variety of alpha,beta-unsaturated ketones, even without other electron-withdrawing functional groups, could be reduced on the alkenic double bonds with high selectivities employing amido-rhodium hydride complex in aqueous media, and up to 100% chemoselectivity has been achieved. It is notable that the chemoselectivity was improved significantly on going from organic solvent to water. Moreover, a 1,4-addition mechanism has been proposed on the basis of the corresponding experimental details and computational analysis.

The highly enantioselective Michael addition of malononitrile to acyclic and cyclic alpha,beta-unsaturated ketones has been developed. The Michael reaction catalyzed by a primary amine derived from quinidine proceeded smoothly and provided the desired adducts with excellent enantioselectivities (83-97% ee).

[Reaction: see text]. Asymmetric transfer hydrogenation of ketones, especially alpha-bromomethyl aromatic ketones, catalyzed by unmodified, hydrophobic transition metal-amido complexes (TsDPEN-M), was performed successfully with significant enhancement of activity, chemoselectivity, and enantioselectivity (up to 99% ee) in aqueous media containing micelles and vesicles. The hydrophobic catalyst, embedded in micelles constructed from the surfactant cetyltrimethylammonium bromide (CTAB), could be separated from the organic phase along with the products and was recycled for at least six times.

[reaction: see text] An easily accessible water-soluble chiral o-sulfonated 1,2-diphenylethlenediamine 2 and its mono-N-tosylated derivative 3 were synthesized for the first time. The ruthenium-complex-catalyzed reduction of prochiral ketones in aqueous media has been examined by using 3 as ligand and sodium formate as the source of hydrogen. The asymmetric transfer hydrogenation of omega-bromo acetophenones was achieved, in which only formate displacement occurred when formic acid/triethylamine azeotrope was used as the hydrogen donor.

An important synthon, tert-butanethiosulfinate (2), has been effectively resolved by forming molecular complexes with (R)-2,2'-dihydroxy-1,1'-binaphthyl (BINOL, 3) in high enantioselectivity (>99 % ee). The present procedure represents the first example of the resolution of thiosulfinate. The mechanism of chiral discrimination is discussed in terms of molecular recognition based on IR and Xray analyses of the diastereomeric complexes during the resolution. In the less-soluble complex, (R)-3 and (R)-2 self-assembled as a linear supramolecule; however, in the more-soluble complex, (R)-3 and (S)-2 formed a simple bimolecular complex by one stronger hydrogen bond. Hydrogen bonding is the major driving force for effective resolution.