Technical Study Of Nitrogen Assisted Cyclic Steam Stimulation In Jinglou Oilfield

Jinglou oilfield is the major oilfield of Henan oil region, whose main oil is heavy oil,extra heavy oil, ultra heavy oil, and extra heavy oil domains about70%. After several cyclescyclic steam stimulation, due to the heterogeneity of both horizontal and vertical, thedevelopment effect becomes worse and the problems like great pressure drop and naturaldecline efficient increasing gradually are emerging. Though nitrogen assisted steamstimulation has been applied to the field, the mechanism of improved recovery is not veryclear. Aiming at these problems, the thesis studied the mechanism of nitrogen/nitrogen foamenhanced extra heavy reservoir by physical simulation and optimized the injection andproduction parameter by numerical simulation.The results of physical simulation showed that: the main mechanism of nitrogenassisted cyclic steam stimulation is the increase of heated radius; supplying driving force forthe puff process and certain capacity of profile control. As to the nitrogen foam, the mainmechanism is its good profile control ability and displacement efficiency. Sensitivity testsshowed that: when the oil saturation is lower than40%or the permeability differential islarger than8, the development effect became worse. Based on the geological data,geometrical model was built, and to different remaining oil saturation, the best injection timefor nitrogen/nitrogen foam assisted cyclic steam stimulation is not as earlier as better. Theinitial of development is mainly by injecting steam. When the saturation is between60%and70%, the best injection time is the fifth cycle, while the saturation is between40%and50%,the best injection time is the fourth cycle.