Study On Residual Oil Distribution Of Chang 4+5 Reservoir Group In Well Aarea Of Wuqi Oilfield

Residual oil is the raw oil that remains underground after petroleum has been distilled because of improper method and strategy development.Study of residual oil is a fundamental way in stabilizing oil production by water control and oil recovery improvement.After almost 9 years of waterflooding development,A well block in Wuqi oil field has come to its middle and later development life.Lack of clear understanding of the structure and sedimentary reservoir,production in study area is declining rapidly and water content experiencing rapid increase,resulting in the difficulties in the water control and oil stabilization as well as understanding of residual oil.Based on the theories of sedimentary and oil field development geology,4+5₂² oil bearing unit in Wuqi oil field was studied.Strata in research area was re-divided and correlated followed by the discussion of sedimentary facies and the heterogeneity of the reservoir.Well logging data was explained for the accurate calculation of reservoir attribute parameters.Software was used to build structural model,lithofacies model and property models?porosity,permeability,oil saturation?of Chang 4+5₂² unit.Parameters such as reserves,total oil production,total water production and daily oil and water production of a single well were under history matching.The distribution of residual oil was predicted,providing theory guide to the efficient oil development in research area.The Chang 4+5 oil bearing unit of A well block in Wuqi area was divided into Chang4+5₁,Chang 4+5₂¹,Chang 4+5₂² sub-units whose thickness varies little.Chang 4+5 is delta front subfacies deposits and develops four sedimentary microfacies such as subaqueous distributary channel,underwater natural levee,estuary sand bar and interdistributary bay,among which microfacies of subaqueous distributary channel is widely developed in Chang 4+5₂².The Chang 4+5 oil bearing unit is highly heterogeneous as a whole,and the Chang 4+5₁ has the strongest heterogeneity,the Chang 4+5₂² is relatively weak.Finally,the research on residual oil distribution was carried out by using 3D geological modeling technology and reservoir simulation method.The results show that there are still a large amount of residual oil in Chang 4+5₂² unit,which is mainly distributed in the imperfect mining area and the area with poor water injection.The formation and distribution of residual oil are mainly affected by the microstructure?reservoir heterogeneity and well pattern distribution of the area.At the same time,the potential and specific methods for remaining oil development in the area were mentioned in the thesis.