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The crude oil of H oilfield contains wax and asphaltenes, and the formation water salinity is up to 160000-220000mg/l, so there is a tendency that the asphaltenes and scale will be deposited in the wellbore during the course of well production, which will influence the normal production greatly. It is necessary to make clear the sedimentary law and corresponding measures. The content of organic and inorganic of wellbore deposits of H oilfield is analyzed through a series of laboratory tests. On the base of the test results, integrated with comparison of conventional deposit prevention and removal technologies, chemical and mechanical methods are recommended. Moreover, formulation of the acid cleaning agent is determined and the principle and process of mechanical removal method is presented.

Corrosion experiments were done to test the corrosion behavior of 3Cr steel in different water cut content. The experimental result shown that with the increase of water cut, the corrosion rate was increase especially in the high water cut environment. From XRD and SEM analysis result, the corrosion composition was changed with the water cut content. The corrosion film became less protective with the increase of water cut.

Corrosion experiments were applied for 13Cr steel. Through the experiments, the corrosion rate of 13Cr steel in different temperature was tested. The corrosion rate of 13Cr steel was increased with the increase of temperature. Moreover X-ray diffraction analysis and scanning electron microscope analysis were applied to understand the corrosion behavior of 13Cr in micro-scale.

A FEM-DEM approach was applied to investigate progressive rupture of concrete structures due to dynamic load including earthquakes. In the proposed method, the finite element method (FEM) designed for modelling stressed and deformed solids has been combined with the motion tracking capability of discrete element method (DEM). A fracture model combining single and smeared crack model is used in our simulation. The FEM-DEM method was used to simulate both the intact concrete behavior and the development of fractures in the indirect tensile test. The simulation results identify the failure mechanisms and validate the nature of tensile crack initiation and propagation in concrete disk. In particular, a comprehensive study on the seismic rupture of the Koyna dam during earthquakes is performed using the proposed method. It is shown that the proposed method can predicate the formation and propagation of cracks in concrete dam due to earthquakes.

We applied the discrete element method (DEM) to analyze the normal impact properties of elastoplastic spherical particles. DEM simulation of impact between two identical elastoplastic spheres is carried out to validate the proposed model. The numerical results show well agreement with the FEM solution. Based on this model, the effects of impact parameters such as velocity, yield strength, elastic modulus, Poissons ratio, and mass density, on the loss factor in impact process, are then analyzed.

Alternating current field Measurement is one of the important progresses about electromagnetic nondestructive testing in recent years. Alternating magnetic fields excitation testing model is established by using electromagnetic simulation software ANSOFT, a flat plate crack defects are simulated. By analyzing its principle, crack depth and the width change influence on test results, finally the simulation results are verified by the method of experiment. The experimental results are consistent with the simulation results. The results show that this differential probe has good effect on crack defects test.

In order to determine stress concentration zones and defects on the surface of ferromagnetic components, the empirical model decomposition (EMD) method was proposed to eliminate noise interference of metal magnetic memory signal. Tensile-tensile fatigue test of 16MnR steel with prefabricated defects were carried out, and magnetic signals were measured using GMR sensor. The original metal magnetic memory signal was first decomposed into different intrinsic mode functions (IMF) and a residue, and reconstructed signal was obtained on the basis of the degree of the correlation coefficient. Results indicate that the reconstruction signal displays the maxima at 30mm, and there is a good correlation between the real maxima and the stress concentration zone. The EMD method is a effective signal processing method about magnetic memory signal containing some interference factors.

Slow strain rate tension stress corrosion cracking test was applied to test the SSC-resistant ability of L80 and C90 steel. The experimental result showed that: L80 steel occurred plastic fracture and had good resistance to SSC; C90 steel occurred plastic-brittle fracture and the ability of SSC-resistance was worse than that of L80.

Formation porosity near the wellbore can be changed by massive sand production, so it is impractical to use the initial formation porosity in downhole operation design in unconsolidated sand reservoir. The numerical method for sand prediction is limited for its complicated calculation procedures. An analytical model for porosity variation calculation is developed by coupling the material balance equation with the critical fluid drag force. With the result of sand production simulated test, the model can quantify the relation between sand production rate and formation porosity variation. Application of the model in oil field shows that it is simple and practicable for field engineering design.

Downhole Gas Compression (DGC) is an entirely new powered artificial lift technology specifically for natural gas wells. The technology offers the opportunity to increase production by 30-50%, significantly improve reserves and delay the onset of liquid loading. Key application of DGC is for use in deeper partially depleted reservoir wells encountering liquid loading. The research progress of DGC is introduced in this paper and the results of theoretical and experimental study of DGC are investigated. Moreover, the adaptability and application prospect of this new technology is analyzed. There are many gas fields in China faced with problems about effective drainage and recovery enhancement, such as the mature gas fields in Sichuan and Ordos Basin. DGC will have a good application prospect in China and further study of the DGC technology is recommended.

Development of a single bubble in free space under the canonical ensemble was studied by using molecular dynamics simulation method. The detailed dynamic characteristics in the evolution process were analyzed by calculating the displacement of molecules, density, diffusion coefficient, pressure and potential energy of bubble. The results indicate that the evolution is divided into three stages according to the change of bubble potential energy, which are expansion, compression and balance state respectively. The temperature and density have significant influences on the final state of bubbles. The bubble in the liquid with larger density has a higher transition rate. The collapsing speed of bubble becomes faster with temperature increasing.

Multiple Input-Multiple Output (MIMO) radar is the recent emergence of a new radar technology. This radar system is a new concept advanced for the inadequacy of the traditional system, it use spatial diversity and angel diversity to avoid multipath fading. In this paper, we mainly analyze the detection performance of MIMO radar, and at the same time compared its detection performance with phased array radar under the same conditions. This paper first established MIMO radar’s signal model based on the distribution of sources, and then analyzes the affect of radar’s detection performance through changing the number of antenna. The simulation result showed that the MIMO radar has a good detection performance compared with phased array radar in low signal-noise-ratio(SNR).

An appropriate shape designing of a snowboard course (currently known as a "halfpipe") is the precondition to achieve higher scores in a competition. We divided the whole process into four procedures: Air, Transition Processes and Pump, Twist Techniques. Elliptical transition of a halfpipe was put forward instead of the traditional circular one to optimize the shape, by simplifying this problem into some dynamical partial differential equations. We proved three theorems and used numerical methods to calculate the optimal value. The optimal shape we designed is mainly based on the initial velocity and combines all the known targets into two calculable physical variables. Simulation with common parameters from FIS indicates that our results accord with the practice and gives us the optimal shape of the snowboard courses for various levels of competition with different initial velocities. Plenty of sensitivity analysis shows that our designing is robust.

A special grinding device is designed to solve the problems of the shape precision, surface quality and grinding efficiency. The device is based on the sine generator and triaxial speed to achieve the ideal Grinding trajectory. The accuracy of grinding in spherical valve core & surface quality is assured and improved by three-dimensional elastic support, pressurized floating contact and auto centering device in core and lapping tools. The grinding efficiency is highly enhanced by using the lateral and vertical speeding workpiece installration and the automatic control. The device is worth widely being applied to achieve a good large diameter hemispherical workpiece grinding.