Design Of Degradation And Lifting Process Of Outburst In Wellbore Oilfield

As the demand for petroleum increases dramatically, and onshore production and offshore light oil output decreases gradually, deepwater heavy oil resource becomes more and more important in energy strategy. It is of great importance to exploit deepwater heavy oil scientifically and effectively to our energy security. It is our petroleum technology workers’ obligation to break the bottleneck of deepwater heavy oil exploitation and the foreign monopoly.Congo LIBONOLO oil field is exploited by CNOOC abroad. The water depth surpasses1000meters. The low temperature environment of seawater makes the heavy oil loose plenty of heat when it flows through the low temperature region, which leads the viscosity of the heavy oil to increase in the wellbore. The heavy crude flows difficultly in the wellbore due to its high viscosity, and wellbore visbreaking craft can guarantee the heavy oil to flow smoothly through the wellbore. Basing on the experiment and theoretical calculation, we select the wellbore electrical heating as the optimal visbreaking craft as well as considering the specific deepwater operating environment and well test requests. The PCP is selected due to its adaptation to high sand content heavy oil exploitation.On the basis of mass conservation, momentum conservation and relevant heat transfer theory, a coupled pressure and temperature model is deduced. Joule-Thomson effect, heavy oil friction heat and total heat transfer coefficient variation along the wellbore is considered in the model, and numeric iteration is used to solve the governing equations.Basing on the above model, we have developed "Wellbore electrical heating visbreaking craft design program in deep water heavy oil field " utilizing Visual Basic6.0, and the actual parameters of Congo LIBONOLO is used to make analysis. The calculation result indicates that:the production fluid temperature increase as electrical heating power and insulating level of the insulation tube is enlarged. However, the application effect to use the electrical heating or insulating tube individually is not satisfying. The compound craft to use electrical heating and insulating tube simultaneously can heat the production fluid economically and effectively, which can lead the production fluid to flow smoothly up to the well head; Cable-in-rod through pump heating craft can decrease the viscosity of production fluid near the entry of the PCP and increase the entering pressure of the production fluid to the PCP, which relieves the problem of entering the PCP for the heavy oil; The production fluid temperature increases and then turns steady after well opening; Wellbore fluid temperature increases and then turns steady after well opening; Production fluid temperature increases as the water content enlarges. Production temperature enlarges as the mass flow rate becomes bigger when there is no heating, but the situation becomes complex when there exists heating in wellbore.We design wellbore electrical heating craft for Congo LIBONOLO E-1using our model. Considering the power to lift the production fluid and PCP characteristic curves, specific PCP is selected. The application result implies the feasibility and correctness of the model, which can give guidance for electrical heating visbreaking craft in deepwater heavy oil fields.