At present,most oil fields in China have entered the high water cut period,and the flow characteristics of produced fluid have changed, so it is possible to reduce the temperature of gathering and transportation.However,there are relatively few studies on the influence of pipeline materials on low-temperature gathering and transmission characteristics. Therefore, the characteristics of low-temperature gathering and transportation of high water content crude oil in steel pipe and fiberglass pipe are studied.The results show that the wellhead back pressure rises and the oil temperature at the end of pipeline drops slowly after the water content of the pipeline is reduced. The wellhead back pressure rises differently under different water content.When the water content is the same, the temperature of fiberglass pipe is lower than that of steel pipe, and the minimum water content of fiberglass pipe for low-temperature gathering and transportation is lower than that of steel pipe under the same condition.Based on the experimental data of viscosity wall temperature,the calculation models of different pipe materials are obtained,and the calculation results are accurate, which has a guiding significance for the feasibility judgment and safe operation management of the oil field in the high water cut period.

The solidifying point of shale oil is high, and the wax content is high and the emulsification degree of shale oil is high. As a result, it is not easy to dehydrate shale oil emulations by using the traditional thermochemical method, which is difficult to meet the export standard. High frequency pulse dehydration technology is an effective method to dehydrate, but there are few studies on the optimization of treatment parameters of shale oil produced fluid. In this study, the effect of high frequency pulse dehydration technology on Dagang shale oil emulsion was studied, and the treatment parameters were optimized. The results show that high frequency pulse dehydration technology can achieve effective demulsification of shale oil produced liquid and significantly reduce the water content of shale oil. Through the comparison and selection of treatment parameters, it is found that the increase of electric field intensity and electric field frequency is conducive to improve the dehydration efficiency. Besides, there are electric field action time, operation temperature and demulsifier concentration parameters with the best dehydration efficiency. It is proposed that under the electric field strength of 200 kV/m, electric field frequency of 5 kHz, electric field action time of 60 min, operating temperature of 75 ℃, demulsifier mass fraction of 0.010%, the water content of shale oil after dehydration is 0.48%, and the comprehensive benefit is the best. The research results provide technical support for the optimization of shale oil produced fluid treatment parameters.