Study And Application Of Deep Profile Control Technique Of Dongying Formation In Hejian

The reservoir of Dongying formation in Hejian is the main body of Hejian Oilfield,which accounts for 53% of the total geological reserves and 55.8% of the total annual production.More than 40 years of development,the reservoir gradually exposed many problems,such as the structural imbalance of water absorption as well as the profile of liquid production,the water content of the effective oil wells was rising rapidly,especially the development contradiction of serious water flooding in the eastern well area.Although the Tertiary oil recovery technology has been applied to exploit the potential of residual oil in the reservoir since 2006,due to the limitation of the measure technology and the cognitive level about types and distribution of the residual oil,the effect of increasing oil was general.At present,the Dongying reservoir in Hejian has entered the "double-high" stage,that is,high water content of 83.33% with high recovery degree of 36.6%.In order to solve the problems in the development of the reservoir and to improve the recovery of the old reservoir continuously,firstly,the research started from the geological foundation,on the basis of the previous experience on profile control and flooding of single well group with the applications of sublayer splitting calculation and numerical modeling,provided further research on the laws of water flooding and residual oil which made the exploring purpose more clear.Secondly,on the basis of improving the compatibility of injection agent and formation water,the laboratory experiment of flooding system was carried out,and came up with "gel& microballoon sphere" system whose plugging effect was much better.Thirdly,the research took the smallest injection-production well group as the unit to implement the technical countermeasures of deep regulation and flooding which was suitable for Dongying formation in Hejian,just one well with one strategy.At the same time,the field application and effect evaluation are carried out.In the course of the research,the method of "separating adjustment" was widely adopted,and established the three-dimensional adjustment system of reservoir planely and longitudinally.The double-effect,that is physical combined with chemical effect of separating adjustment expanded the sweep volume of water flooding and maximized the effect of deep profile control.In the end,the application of this technology to Dongying reservoir in Hejian shows that the overall natural decline of the reservoir has been reduced by7.2 percentage points,the water cut has decreased from 89% to 85%,and the cumulative increase in oil production has been achieved by 22134 t.This technology is significant for some old reservoirs in the later stage with high water cut on exploring the residual oil potential.