Three Typical SAGD Horizontal Producer Temperature Modes and Enhanced Measures in Heterogeneous Super Heavy Oil Reservoir-A Case Study in FC Project of Xinjiang Oilfield

Steam assisted gravity drainage (SAGD) technology by dual-parallel horizontal wells is matured commercial technology. In China SAGD was used commercially from 2012, current SAGD production rate is 17,000bbl/d. However, because of reservoir heterogeneity the production performance is not expected, oil rate per well is low, steam oil ratio (SOR) is higher. FC project in Xinjiang Oilfield has been operated for 6 years since 2012, however, the expected oil rate and SOR are still not gained. By analyzing various data about 168 dual-horizontal well patterns, three typical SAGD horizontal producer temperature modes are put forward. They are basically uniform mode (Type I), heel section tending to steam breakthrough mode (Type II), toe section non-start-up mode (Type III) respectively. Different temperature modes represent different recovery and producing characteristics, appropriated enhanced measures should be put forward. Basic uniform mode is 27% (45 well patterns), its characteristic is the temperature difference along the horizontal producer is about 30℃ and the whole well section is utilized basically. Heel section tending to steam breakthrough mode is 47% (79 well patterns), the temperature of heel section is 80℃ higher than that of toe section. There are hotspots near heel section, and steam is easy to break into producer in heel section. Liquid production intensity (t/d/m) of heel section is 5-10 times lower than that of toe section. Toe section non-start-up mode is 26% (44 well patterns), the temperature difference is more than 100℃ along horizontal producer, toe section cannot be start up efficiently. Different enhanced measures have been applied to these three types. For Type I, sub-cool is lowed from 30-40℃ to 8-15℃ to increase liquid production intensity, then the oil production and SOR are enhanced. For Type II, an appropriated length electric heater is placed in the toe section to increase its temperature and narrow temperature gap between heel and toe section. Liquid production intensity of toe section is increased by this measure. For Type III, assisted vertical injector wells are used to utilize the toe section and make the steam chamber develop uniformly in toe section.