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In order to reduce the adherence of platelets to the pyrolytic carbon surface of cardiac valve prosthesis, micro patterns are textured on the surface by nanosecond laser. As the basement, the textured pyrolytic carbon then reacts with formamide and zinc by hydrothermal method for preparation of globular ZnO film. In the process, the formamide concentration should be 10%, temperature at 70°C and the time lasts for 24 hours. Subsequently, scanning electron microscope (SEM) is employed for observation of its characteristics and morphologies and Optical Contact Angle Measuring Device (OCA) for measurement of contact angles. The experimental results indicate that the ZnO film produced on the textured pyrolytic carbon surface is a globular structure, similar to dandelions and the contact angle with super-hydrophobicity feature is 155 o. So it is concluded that globular ZnO film makes the rough pyrolytic carbon surface endowed with the characteristic of super-hydrophobicity.

The research of structural-deformed coal is important in coalbed methane exploitation. Compared with those of undeformed coals, the geophysical logging characteristics of structural-deformed coals show lower amplitude value of deep lateral log (LLD) and density log (RHOB) and higher amplitude value of acoustic log (AC). In the southern Shizhuang Block, the structural-deformed coal is commonly developed, with the thickness ranging from 0.6 to 1.1 m. The thickness of structural-deformed coals accounts for 11.5-18.5% of the total coal thickness. In general, the structural-deformed coals are more developed in the west than those in the east of the study area.

This paper focuses on the research of the vertical and regional distributions of stress characteristics in the Shizhuangnan coalbed methane field, southeastern Ordos basin. The minimum and maximum horizontal stresses were firstly calculated by the breakdown pressure, closure pressure and tensile strength of the fracturing data of key wells. Then the calculated results are compared with the results calculated from the natural gamma-ray, density and acoustic logging data and Anderson’s Model. Based on the comparison, the residual stress in the Anderson’s Model is corrected. By adding the residual stress data in the Anderson’s Model, the modified model can be well used for evaluating the stress characteristics in the area with complex structure types. Finally, the distribution of stress characteristics in the Shizhuangnan coalbed methane field were evaluated by using the modified Anderson model.

Gas content is one of the most important factors in the process of exploration and development of coalbed methane (CBM). The relationships between gas content and characteristics of geophysical logs have been evaluated for the No. 5 coal seam in Weibei CBM field. It is found that the main well loggings that have good responses for gas contents are the compensating density, natural gamma-ray, compensating neutron, natural spontaneous potential and acoustic. A theoretical model was proposed to calculate the gas content by using these well logging data and as well as the burial depth. The calculated gas contents fits well with the measured data with a small relative-error of 0.38-5.05%. In the model, both tectonic movement intensity and the gas accumulation were taken into consideration. Key words: Coalbed methane, Weibei coalfield, Ordos Basin, Gas content, Geophysical logging

As a sequel to the study in determining the permeability of the porous media composed of obstacles of different sizes, exhaustive numerical calculations were conducted using the same two-dimensional numerical models of square rods as in the previous study. The models consist of collections of square rod obstacles of two-, three-, four- and five-different sizes. Computations were carried out to reveal the details of microscopic velocity and pressure fields. There results are integrated to find the macroscopic pressure gradients for collections of multi-sized obstacles. The Ergun type general formula has been proposed along with a definition of an effective average size, which, when substituted into the formula, yields a reasonable estimate for the macroscopic pressure drops in multi-sized obstacles.