Density functional theory was employed to explore adsorption mechanism of benzoic acid and toluene molecules on calcite surface, and to analyze influence of polarity on the adsorption. It showed that benzoic acid was tilted adsorbed on CaCO₃(104) surface in the form of undissociated molecules and in monodentate mode, while toluene was parallel adsorbed. Geometrical structure of organic molecules changed significantly during the adsorption, in which the deformation of benzoic acid was much greater than that of toluene. Meanwhile, electronic structure of the adsorption system was also changed. During the adsorption of benzoic acid, Ca-O ionic bond and H-O covalent bond were formed. However, there was only weak hydrogen bond between toluene and CaCO₃(104) surface. Obviously, adsorption intensity of benzoic acid (polar molecule) on CaCO₃(104) surface is greater than that of toluene (non-polar molecule). It provided theoretical support for EOR and mineral flotation engineering.

We studied adsorption characteristics of oil-water system on calcite and dolomite surface with molecular dynamic simulation. To study wettability of calcite/dolomite surfaces, we analyzed equilibrium conformation, relative concentration, radial distribution function and adsorption energy of calcite/dolomite-oil/water system. Then, we proposed a two-step adsorption mechanism. It shows that dolomite-oil/water system is more easily to achieve thermodynamic stability and is more stable; A water film is formed on calcite and dolomite surfaces, which is a double-layer structure; There are interactions among oil molecules, water molecules and the crystal surface; Attraction of dolomite surface to oil and water molecules is stronger than calcite. Finally, we divided the adsorption process into two steps:Water molecules adsorbed on crystal surfaces form a tightly adsorbed layer under van der Waals forces, electrostatic forces and O(CaCO₃,CaMg(CO₃)₂)-H(H₂O) hydrogen bonds. In addition, the remaining water molecules move to the crystal surface form a diffusion layer under the influence of O(H₂O)-H(H₂O) hydrogen bonds. It reveals wettability formation and alteration mechanisms on calcite and dolomite surface, which paves a foundation of further enhance oil reovery.

With dynamic coupling model of fractured anisotropic full-tensor permeability, a complete three-dimensional three-phase fluid-solid coupling model for anisotropic ultra-low permeability reservoir is established. Using modular explicit coupling iteration, we establish a fluid & solid coupling seepage numerical simulation method considering fracture deformation and corresponding coupling program. It shows that for fractured reservoir, with change of reservoir pressure in process of mining, rock deformation and anisotropy of reservoir medium strain can make various deformation degree in multiple sets of cracks, cause nonlinear change of fracture permeability, which makes principal value of reservoir fracture permeability tensor rotating, changing flow direction, affecting reservoir development effect.

A model for flow in a 3-dimensional 3-phase anisotropic oil reservoir is established and applied to reservoir development.The model includes a complete anisotropic permeability tensor.It characterizes the anisotropic permeability distribution with different principal directions in different regions.It calculates the fluid flow,the residual oil distribution and the pressure distribution in anisotropic reservoirs accurately.