Optimization Design Of The Rod Pumping System For SAGD Production Wells In Heavy Oil Reservoir

The success and effective implement of SAGD technique depends largely on the coordination between lifting capacity and steam chamber oil production. At present, the study of optimization design of the rod pumping system for SAGD production wells abroad and domestic is in primary stage, a complete application procedure and systematic theory didn’t formed yet. The main existing problems including oil wells performance prediction, the calculation of fluid pressure and temperature distribution, study of viscosity and temperature relationship, pump efficiency calculation, etc. Dealing with these problems, oil performance calculation model for three production period that concerns about well spacing and steam chamber extension is built in consideration of the particular of SAGD. And some affecting performance factors are analyzed, such as reservoir geology factors and lifting factors. Establishes and modifies Beggs-Brill pressure gradient formula, temperature distribution mathematical model and steam ratio distribution model. The relationship between viscosity and temperature are obtained by experiments. Pump efficiency calculation model is built that concerned about stroke loss, leakage, volume ratio, flashing evaporation. In conclusion, for SAGD production wells in heavy oil reservoir Establishing the optimization design of the rod pumping system for SAGD production wells in heavy oil reservoir that take system efficiency as optimization goal, and the calculation software is compiled at the same time. The results show that, comparing the calculation results with the field data, performance prediction model can achieve high accuracy, the relative error as low as 6.78%. Porosity plays the most important role to performance. While the average reservoir thickness plays the second role, the movable oil saturation, horizontal well length and effective permeability do less impact to performance. The conclusions that get from experimental studies about relationship between oil viscosity and temperature show that oil viscosity decreases with the increment of temperature. While taking the water ratio value of 0.2 as boundary, relationship between viscosity and water ratio rises firstly then drops later. Injection wellbore fluid temperature decreases with the increases of well depth in different liquid production, and the more production, the higher temperature is. Steam ratio decreases with the growth of well depth, and decreasing amplitude trend to flatten at the depth of 1350 meter. Pump effective analysis show that the relationship of pump efficiency, system efficiency with submergence depth in different water ratio has the same changing trend. Taking the submergence depth value of 620 meter as boundary, relationship between pump efficiency and submergence depth rises firstly then drops later. Taking the water content value of 0.2 as boundary, relation between pump efficiency and water ratio rises firstly then drops. The changing trend between pump efficiency and water ratio in different water ratio tends to be the same. The deeper of submergence depth, the higher pump intake pressure is. As a result, high coefficient of admission is obtained that enhances the pump efficiency. On the contrary, high water content will lead to flash evaporation and the pump efficiency won’t increase. At the value of 20% for water ratio, oil well has the lowest pump efficiency. The research results can provide theory guidance for effective and safety lifting of SAGD well in heavy oil reservoir.