Development and Application of Borehole Insulation Techniques for the Development of Heavy Oil Production in the Dongxin Oilfield

Due to thermal loss and temperature drop during oil lifting in the wellbore, the viscosities of heavy oil may increase rapidly and so will the lifting loads. Accordingly, it is important to develop effective insulation techniques for borehole to enhance productivity of heavy oil. The Hansan mathematical model for calculating the heavy oil wellbore temperature was established based on the theories of thermal transmission. The wellbore temperature distribution in Well Y12X2X3 was calculated and analyzed. In addition, the liquid-producing capacity, the type and length of insulation tubing were analyzed and optimized as main factors of wellbore temperature distribution. Reasonable wellbore heat preservation measures included choosing insulated tubing which length with a length of 1, 000 m and increasing the fluid volume from 11 m3/d to 20 m3/d. Field application showed that the wellbore temperature was enhanced from 20.5℃ to 41.5℃, and the viscosity of crude oil above a depth of 1, 000 m was greatly reduced. Eventually, the fluidity of oil as well as the filling level of the rod pump were also increased while the pumping efficiency increased by 47%. The results showed that the mathematical model for calculating the heavy oil wellbore temperature could describe the wellbore temperature accurately and the resulting effective wellbore insulation measures could be followed to enhance heavy oil productivity.