With the wide application of clean energy, improving the transportation efficiency of gas pipeline has become a hot issue, among which, it is very important to reduce the friction resistance in the pipeline transportation process. In order to explore the application effect of triangular riblet in the drag reduction of gas pipeline, ANSYS?FLUENT software was used to numerically simulate the turbulent flow in smooth pipeline and riblet pipeline. The results show that: in the near wall area, the velocity profile of ribbed pipe and smooth pipe has a big difference, and the difference is small in the mainstream area. The drag reduction effect of riblet structure is mainly based on the near?wall surface. The riblet structure pushes the vortex away from the wall surface, filling the rib bottom with low?speed fluid, reducing momentum exchange near the wall surface and friction resistance. Compared with the smooth wall surface, the riblet structure with the size of s＝h＝0.516 5 mm has a drag reduction effect of 4.38%.

Soil collapse in natural disasters seriously threatens to the stability of buried pipelines. In order to study the stability of buried pipelines in the suspended collapse area, based on the finite element method,the displacement, strain and stress of buried elbows with different wall thickness and outer diameter in the suspended state were studied. Based on the eigenvalue buckling theory, the ultimate length that the buried elbow can withstand when the soil collapses under certain conditions was studied. The results show that reducing the buried depth, increasing the outer diameter and wall thickness can effectively reduce the displacement of pipeline in soil collapse. The stress and strain of the pipeline occur in the center of the collapse area and the fixed ends of the two sides; the increase of the outer diameter and wall thickness of the pipeline can inhibit the occurrence of local excessive stress to a certain extent. The ultimate length of the buried elbow in the goaf is about 87 m, and improving the outer diameter and wall thickness of the pipeline can enhance the buckling resistance of the buried elbow in the process of soil collapse.

In order to study and determine the optimal compounding system that can improve the stability of heavy oil emulsion in Liaohe Oilfield and the law of emulsion stability under different conditions, a focused beam reflectometer(FBRM) and rheometer were used to pass four factors and three levels. Orthogonal experiment with three indexes explored the change law of droplet average particle size, dispersion degree and emulsion viscosity, and investigated the influence of external factors on the stability of emulsion under compound system. The results show that the compound emulsifiers with the mass fractions of OBS?50, AEO15/OS?15, OP?15, and sodium with mass fraction of 4.0%, 4.0%, 1.4% and 1.4%, respectively, are the most beneficial to improve Stability of heavy oil emulsion in Liaohe Oilfield; there is a positive synergy between average particle size and dispersion, and an inverse relationship with the viscosity of the emulsion; the increase in temperature, volume ratio of oil to water will weaken the stability of the emulsion; stirring rate, ore The increase of the degree of chemical conversion can improve the stability of the emulsion; when the mass fraction of the mineralized NaCl is 0.2% to 1.0%, the stability of the emulsion can be greatly improved, and the quality fraction of the emulsion can be further improved. The lifting effect is not obvious.