Design And Experimental Research Of Inline Axial Swirling Per-dehydrator

With the increase of the production years of the oil field,the water cut of wellstream increases yearly,and the production cost increases significantly.The conventional gathering and transportation process is difficult to deal with this high water cut situation.To save energy and reduce consumption,while ensuring the stable or upper production of crude oil,the efficient pre-dehydration from wellstream is an effective scheme to solve the bottleneck problem of oil field gathering and treatment in the period of high water cut.The oil-water cyclone separation technology using supergravity is very popular in the aspect of pre-dehydration from wellstream because of its high separation efficiency and compact structure,and also provides technical support for offshore oil and gas gathering and transportation treatment with more complex production conditions.In this paper,the technology and equipment of pre-dehydration from wellstream at home and abroad are systematically summarized.Based on the theory of liquid-liquid cyclone separation,an inline axial swirling pre-dehydrator is proposed,and the design method is established.Through theoretical calculation,the main structure design of inline axial swirling pre-dehydrator,such as starting zone,stable swirling zone and separation zone,is completed.The structural design of three kinds of static swirling blades is discussed emphatically,and the auxiliary structures,such as inlet and blade carrier,are completed.Finally,the structural dimensions of the indoor prototype and the structural form of the engineering prototype are preliminarily determined.To verify the feasibility of the design method and structure scheme,the flow and oil-water separation process in the inline axial swirling pre-dehydrator were studied systematically by CFD numerical simulation.The research results show that a stable swirl flow is formed in the inline axial swirling pre-dehydrator,and the dehydration rate can reach more than 51%,which meets the design requirements.On this basis,the all-factor and multi-objective optimization design of the main structure of the equipment is carried out by using the response surface method(RSM),and the optimal combination of structural parameters is obtained.Besides,the influence of operation parameters on the pre-dehydration performance is investigated,which lays a foundation for indoor experimental research.According to the results of numerical simulation and optimization,an indoor experimental prototype with a processing capacity of 1.00m~3/h is designed,and a detailed experimental study is carried out.The research results show that when the inline axial swirling pre-dehydrator treats the simulated produced liquid with a water cut of 60%-90%,the dehydration rate can reach more than 50%on the premise that the oil concentration at the water outlet is lower than 1000mg/L.Through the comparative experiments of different static swirling blades,it is proved that the circular blades can effectively improve the separation efficiency and enhance the flexibility of equipment operation.Compared with the conventional tangential hydrocyclone,the inline axial swirling pre-dehydrator performs better in improving separation efficiency,increasing oil droplet size and reducing equipment energy consumption,and has a certain improvement in operation controllability.Among the operating parameters investigated,when the simulated wellstream with water cut of 90%and treatment capacity of 1.00m~3/h is treated,the optimum split ratio is 0.45,the dehydration rate of the inline axial swirling pre-dehydrator is 62.9%,and the oil concentration at the water outlet can reach 432.8mg/L.Based on the indoor experimental results,the engineering prototype with10.0m~3/h processing capacity is designed by theoretical design and similar magnification design,and compared and analyzed through CFD numerical simulation.The results show that the separation efficiency of the engineering prototype of the two schemes is similar,but the similar magnification design can effectively reduce the design cost,shorten the design cycle,and provide an accurate and convenient design method for serialized product design.According to the field conditions,the multi-tube parallel connection of the engineering prototype and the design of the tank head are completed,and the pry structure integrating mixing,separation and testing is completed,which provides technical support for the follow-up field experiments.This thesis has completed a series of related work on the independent design and development of inline axial swirling pre-dehydrator,which provides practical and feasible technical solutions for the efficient pre-dehydration from high water cut wellstream.