Application status and thinking of flow control devices in SAGD

Affected by factors such as reservoir heterogeneity, drilling trajectory, start-up method, and operation strategy, unsatisfactory results are obtained in the development of nearly 1/3 of the dual horizontal wells using steam assisted gravity drainage (SAGD), indicated by uneven downhole temperature, local vapor channeling, and slow oil drainage rate, and low oil-steam ratio. In addition, a large number of heavy oil reservoirs with strong heterogeneity face the problems from economic development of horizontal wells. Flow control devices (FCDs)is deployed to implement segment management, which is one of the technical directions that many oil companies have explored in recent years to improve the development effectiveness of heavy oil. Although FCDs have been successfully used in the water controlling development of conventional oil and gas fields, they face new challenges such as high temperature and pressure, phase change, high viscosity and strong temperature sensitivity of heavy oil, complex emulsification (water in oil, oil in water, and water in oil in water), multiphase composition of oil-water-steam/gas, and sand production in SAGD applications. First, this paper analyzes the problems and technical requirements faced while improving the quality and efficiency of SAGD, and summarizes the operation mechanisms of FCDs under SAGD conditions, such as the pressure loss due to phase change, and additional steam resistance effect; then, it compiles statistics of the application effects of all foreign field test projects, and analyzes the underlying causes for the poor performance of some projects. Further, using typical cases, this paper deeply analyzes the relevant geological conditions, implementation motives, drilling and completion, lifting and operation process, and implementation effects. On this basis, it is clarified that these technology applications at abroad are in the transitional stage from experimental verification to industrial promotion. The challenges and development directions faced by FCDs in SAGD applications are summarized, including the mechanism that restricts the regulation performance of FCDs, and the structural design and screening standards of FCDs based on thermal recovery conditions, integrated geo-engineering design methods focusing on reservoir-wellbore coupling, quantitative evaluation capabilities of FCD performance. Finally, feasible recommendations for domestic applications are put forward.