Conventionally, the start-up method of dual-horizontal wells SAGD is steam circulation. During circulation phrase, the minimum circulation time and maximum heat communication uniform profile are expected to achieve high oil production. Generally, circulation phrase takes 2 to 3 months in Canada in high quality reservoir. For the poor quality reservoir, circulation time will be longer, for example, in China it takes 200-300 days. In order to solve the disadvantages about longer preheating time and preheating ununiformity of the conventional steam circulation method, the electric preheating method is researched, super-longer integrated coiled tubing electric heater is put down to the horizontal wells separately to heat oil formation uniformly.

The heating mechanism of electric heating method is mainly based on the high temperature heat conduction. The method is less influenced by the permeability of reservoir and the viscosity of crude oil, and the heating efficiency is high. Studies show that the electric preheating method is uniform along the entire horizontal section, the effective heating inter-communication between two wells can reach to 100% theoretically, and the preheating time can greatly shortened. The optimizing results in Block Z1 of Xinjiang Oilfield indicate that the electric preheating time of SAGD is 90 days while the steam circulation time is more than 200 days and the inter-communication profile is 100%. The cost of preheating start is reduced from 420,000$ of steam circulation to 220,000$.

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