In the super heavy oil reservoirs of Liaohe Oilfield, the cyclic preheating of SAGD horizontal wells can only be achieved by mechanical lifting due to the deep burial depth and low formation pressure. The cyclic preheating of SAGD horizontal wells becomes even more complicated in terms of injection and production technology due to the limitation of wellbore space, the complexity of the wellbore structure of horizontal wells and the high temperature of produced fluids, leading to great difficulty in controlling the injection and production parameters. Therefore, the test was conducted to enable the injection/production ratio to be 1: 1, meeting the requirement in the reservoir design by optimal pipestring design, optimal selection of injection and production parameters and controlling the backpressure at the wellhead. At the same time, some supporting techniques, such as a new type of dual pipe wellhead for simultaneous injection and production and high temperature lifting technique have been developed, effectively ensuring the success of the cyclic preheating test of SAGD horizontal wells. By monitoring the temperature profile in the upper horizontal well, it was observed that more than 85% of the horizontal interval has been evenly heated. The success of the test has provided valuable experiences and strong technical support for conducting cyclic preheating of SAGD horizontal wells in similar reservoirs in Liaohe Oilfield and other oilfields in China, and even in foreign countries.

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