The Fundamental Research On The Transportation And Processing Of Offshore Heavy Oil

There are rich of oil and gas resources in the ocean of China,the development and utilization of offshore heavy oil fields can improve the current energy consumption.However,heavy oil is characterized with high viscosity,high density and poor fluidity,which results in high pipeline pressure drop during the transportation.In a consequence,the costs of the infrastructure maintenance and operation will greatly increase.It is best to transport the produced heavy oil onto the platform and be processed,before transporting to the land.The viscosity reducing process of traditional offshore oil-water separator is long and low efficient.In combination with the situation of platform,the related processing is analyzed,and proper treatment scheme is proposed.In this paper,three methods were used,including numerical simulation,field survey and experiment,to do research on five different aspects.Firstly,Fluent software were used to simulate the water ring transportation,aiming to study the influence of velocity,width of the annulus and elbow on its stability.Secondly,experiment were carried out to study the effect of microwave with different power and time on the viscosity of heavy oil;Thirdly,experiment were conducted to study the effect of high frequency electromagnetic field on the viscosity of heavy oil;Fourthly,separation effect were compared between the high frequency water coalescence and the traditional water separator by experiment;Finally,all above aspects were integrated to analyze the related technology and process of offshore heavy oil transportation and oil-water treatment.The results showed that: the various oil-water velocities have a great influence on the stability of water ring.When oil and water are with the same velocity,in the range 0.5 m/s~1.5m/s,and the width of the annulus is between 3.6mm~6.6mm,it can form a relatively stable water ring.When the annulus width is 2 mm,it cannot form a stable water ring;When the water and oil velocity is in the range of 0.5 m/s~1.5 m/s,and the velocity of the water is greater than oil,it can form relatively stable water ring;Conclusion can be drawn from calculation and comparison analysis that the unit frictional pressure drop by using water ring transportation is smaller than general pipeline transportation,and the efficiency is also greater than the general pipeline transportation;Microwave heating has greater effect on heavy oil reduction than general heating,especially in the low temperature zone,and with the increase of power and operating time,the viscosity gets higher and higher.When the treatment time is 30 min,the high frequency electromagnetic treatment has a good viscosity reducing effect.The separation efficiency of high frequency coalescence three-phase separator is higher than the traditional separator,with obvious reduction of water cut in the outlet.Finally,the scheme of technology and process of transportation and treatment of oil and water,which will shorten the process,improve the efficiency of equipment and reduce the costs are analyzed.