Nitrogen auxiliary steam stimulation mechanism and the nitrogen additive quantity optimization research

Heavy oil reservoir in Henan oilfield has the geological features of "shallow,thin,heavy and bulk",numerical simulation technology is used to study the 1-3m,3-5m and 5-10 m three thin layer of heavy oil reservoirs nitrogen auxiliary steam stimulation development effect.Nitrogen auxiliary common wet stream,high temperature wet steam and over heat steam has been implemented in different thickness heavy oil reservoir to increase oil,reduce steam effect and compare and analyze reservoir features.Nitrogen auxiliary steam stimulation to enhance recovery has been summarized.The result shows that nitrogen is added to keep strata pressure,extend steam stimulation period because nitrogen has own characteristics of compressibility,expansibility,small thermal capacity and low viscosity.Meanwhile,nitrogen drainage and plugging improve the wave and volume of steam and increase the oil wash efficiency near the borehole zones.