Search

Cavernous carbonate formations are characterized by strong heterogeneity, which results in the complex electric logging responses and the difficulty in the logging identification and evaluation. Numerical simulation of electric logging tools is helpful to figure out the logging response characteristics in these formations and could provide theoretical support for cave recognition and evaluation. In this paper, based on three dimensional finite element methods, a local refinement technique is adopted for the accurate discretization and simulation of complex sphere caves. Then, the response characteristics and sensitivity of dual laterolog to caves around and penetrated by wellbore are analyzed, finally the differences of sensitive scope between deep and shallow laterolog are studied. The results show that the dual laterolog response decreases significantly when cave exists. Affected by cave boundary and the investigation depth of dual laterolog tool, the logging response for caves penetrated by wellbore is very complicated, however it exhibits parabolic‐like characteristic for caves around wellbore. Compared with caves around wellbore, the dual laterolog is much more sensitive to caves penetrated by wellbore. For caves around wellbore, the maximum sensitive distance for deep and shallow laterolog between the cave boundary and well wall is 0.5 m and 0.3 m, respectively.

With the demand of high-quality and aesthetical products in the domain of medical microbiology, it’s more and more important to join micro weld. Due to traditional joining methods’ difficulty in meeting the demands, laser transmission micro-joining is of great significance. The materials used to laser transmission micro-joining based on the mask are PET, and the experiments are conducted on diode laser. The weld geometry with different gap widths on the mask is demonstrated at the same process parameters. In addition, the causes of forming different morphologies are analyzed. The formation mechanism of weld is analyzed as well. Moreover, process parameters’ effects on joint strength and joint width are deeply explored when gap width on the mask is 0.3mm. The results show that100 um micro weld joint is realized. At the same time, the range of process parameters is determined.

This article uses semiconductor laser for mask assisted laser transmission micro joining PET and PET with clear weld absorbents, the mask slit width is 0.3mm, using CCD to plan experimental design. The mathematical model of joining process parameters with joint strength and joint width was established using response surface methodology. Experimental verification was also done. The actual joint width was compared to mask slit width and the process parameters were optimized. The results show that the mathematical model can response the relationship between process parameters and joining quality, the mask can effectively control the joint width, reasonable process parameters can obtain high-precision, high-intensity joining quality.

n this paper,the laser transmission joint strength is studied with semiconductor laser based on the surface pitting of 304 stainless steel and PA66.Unevenly distributed pits are formed on the surface of 304 stainless steel with 10% ferric chloride solution for two hours, which have certain morphology, depth and size. Different laser power, welding speed and welding pressure are used in laser transmission joining 304 stainless steel and PA66,which 304 stainless steel contains pitting corrosion before and after. The tensile strength test of joined samples shows that: the joint strength of pitted 304 stainless steel and PA66 with laser transmission joining is improved at least 135%; the riveted structure formed at the joining interface improve the joint strength.