Since Moineau developed the single-screw hydraulic machinery theory in the 1930 s, single-screw hydraulic machinery pumps and screw motors have been widely applied in the petroleum and chemical areas [1-2|. Ranked as the third artificial lift method, the screw pump has its unique advantages used for lifting heavy oil reservoirs. Conventional screw pumps consist of rubber bushings and metal rotors, which are mainly applied in cold production and lifting of heavy oils or other viscous liquids [3].In recent years, with the deepening development of ultra-heavy and super-heavy oils, thermal recovery methods of SAGD and CSS steam injections are widely used. Since conventional rubber screw pumps cannot tolerate more than 160°C, they are not suitable for thermal recovery wells. For these kinds of oil wells, TOTAL and PCM companies used the all-metal screw pumps lift method in two wells in the Joslyn oilfield in Alberta for field tests. The API gravity of the crude oil in the oil field is 8° and the 0(1 viscosity is 1.7X106 MPa-s at reservoir conditions [4]. Until the year 2011, a total of 100 all-metal screw pumps have been deployed worldwide in various applications with average run time over two years"[5-7].
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