Experimental research on liquid evacuation was carried out for pipelines containing vertical riser sections, using air and water as medium, gas⁃liquid flow parameters were measured by high⁃speed cameras and data acquisition instruments, the liquid evacuation process is similar to the severe slug in pipeline⁃riser system. The flow characteristics at the outlet of the riser, the pressure fluctuation at the bottom and the riser pressure drop are compared. The experimental results show that when the gas pressure is low, the gas⁃liquid mixture at the riser outlet is stratified flow and slug flow, and when the gas pressure is large, it is only stratified flow. The greater the gas pressure, the faster the movement speed of the gas front, and the shorter the evacuation time. The gas front shows a tendency to break away from the upper wall surface under higher pressure, its tip is closer to the centerline of the pipe, and the slope of the liquid layer behind the gas nose is greater. The pressure at the riser bottom undergoes three processes, which correspond to the three stages of liquid production, blowout, and liquid oscillation. The greater the gas pressure, the greater the increase in pressure at the riser bottom, and the greater the corresponding peak pressure. The riser pressure drop descends more quickly and greater under higher gas pressure.

Since 2016, Ansai oilfield has carried out polymer microsphere profile control and flooding, which has experienced three stages: pilot test, expand the scale of the test and promotion of three stages. The regional stage decline can be reduced about 5%, the overall effect is obvious, but the adaptability and application effect under different reservoir conditions are quite different, For the study of polymer microspheres in multiple media under the condition of mechanism, a group of 60 different particle size of polymer microspheres in different media under the condition of displacement test was carried out. Through the combination of experimental data and field application, the mechanism of microsphere oil displacement (percolation mechanism, change of flow direction mechanis) and the matching relationship between microsphere particle size and reservoir microfractures and pore throat are systematically summarized,which provides a basis for the optimization of construction parameters in the later stage.

The high temperature stability and wellbore cleaning problems of oil⁃based drilling fluid have to be solved when it is used to drill extended reach wells in the KQT gas field located in the East China Sea. For this reason, the key additives of oil⁃based drilling fluid including the emulsifier, wetting agent, rheology modifier and organic clay were selected using the interfacial tension test, emulsifying efficiency test, microscope observation, emulsion viscoelasticity and rheological property tests. After that, the oil⁃based drilling fluid for extended reach wells was developed, and the comprehensive properties were tested. The results show that the drilling fluid has good stability after hot rolled at 180 °C. The selected rheology modifier can enhance the structure strength of oil⁃based drilling fluid, and effectively increase the gel strength and low shear rate viscosity, thus increasing the wellbore cleaning effect. Meanwhile, it has good filtration property and contamination resistance property. This drilling fluid has been used in 4 wells in the KQT gas field, and good field application results are obtained.

The effect of friction to dry gas seal performance can’t be ignored under the condition of high parameter. Based on the structure characteristics of the sealing system and end⁃face, it was established the calculative model of lubricating gas film, used IC⁃EM to divide the grid. Then, conducted numerical simulation to get gas film pressure distribution and velocity distribution by using Fluent software. Finally, it calculated the friction coefficient of lubricating film by the law of Newton internal friction. The result of research shows that the friction coefficient of the lubricating film increases with the increase of the rotational speed, and it decreases with the increase of the medium pressure and the average film thickness in the groove parameters remain unchanged case. When the operating parameters are unchanged, the film friction coefficient increases with the increase of the root diameter, decreases with the increase of the number of grooves and the depth of the groove, and in 75° to 76° spiral angle range is relatively stable.

According to the characteristics of aerostatic dry gas seals and the gas Reynolds equation, Galerkin method was used to derive the variational equations of pressure distribution of the gas film. Based on the gas film boundary conditions, the derivation process using the finite element method of the steadystate Reynolds equations was given. The pressure fitting curves of different thicknesses of the gas films were obtained by using polynomial fitting. In addition, the opening force was carried out. The fitting formula of the opening force and the film thinckness was obtained according to the opening force of the different film thicknesses.The relationship of the film stiffness and the film thickness was obtained by the derivation of the film thickness.The pressure distribution of the stationary seal ring end face was obtained. A parabolic decreasing trend is showed from the orifice to the inner and outer diameters in the radial direction of the stationary ring seal face. Pressure peak occurs at the orifice. With the increase of the gas film thickness, opening force and gas film stiffness decrease.

With the implementation of the three oil recovery technology, although polymer flooding technology improves the oil recovery, it also brings new challenges to crude oil processing and gathering. High return pressure of oil gathering pipeline was caused by wax deposition of polymer flooding pipeline. Study was carried out on the heat cleaning of the polymer flooding gathering pipeline between the wellhead and the metering room after shutdown the well. The effects of heat washing water quantity, hot wash water temperature and different concentration of polymer on the dredging time were studied under different oil gathering radius. It was found that the hot wash water temperature was more obvious in the range of 65~70 ℃, which was calculated by the theoretical formula. When cleaning different polymer concentration pipelines, in the low water conditions, cleaning time of produced liquid with high concentration polymer was relatively longer. With the increase of heat washing water, there was no obvious change in the cleaning time of the sediment with different concentration.

Drilling is a complex transient process. Speed will reduce instantly when drillstring hits a hard rock suddenly and an accelerate process follows it until the speed accelerates to normal value. To observe the dynamic characteristics of drillstring in this case, using the finite element software "ANSYS" to analyze a constant speed process and accelerate processes of drillstring system in vertical well and gets the discipline of drillstring's vibration. The results show that after hitting hard rocks, the collision between drillstring and the borehole wall will happen for the hitting effect between rocks and bit, and the collision strength has a great relationship with acceleration time, if the acceleration time is short, the collision is slight and the force is small; if the acceleration time is long, the vibration will be exacerbated significantly, the collision is more serious and the force increases. In a word, the variable speed of drillstring exacerbates its vibration.

The two oily sludges that with 9.0% and 10.2% oil content were remediated by using the land-farming method. The results show that after 120 days of biodegradation, the oil content decreased to 3.1% from 9.0% and to 4.0% from 10.2%, petroleum degradation rates can reach 65.6% and 60.8% respectively. The saturated hydrocarbon components and relative content before and after biological treatment were analyzed by gas chromatography-mass spectrometry. The long-chain alkanes in 9.0% and 10.2% oil samples are reduced by 39.8% and 42.2% respectively.