| Water flooding is the most common used mode to develop conventional heavy oil.The domestic offshore multi-layered conventional heavy oil used to be developed commingled.After a period of development,especially after water breakthrough,the contradiction between layers becomes more and more serious.To obtain better development effect,it requires urgent attention and research to mitigate the contradiction and find out effective adjustment.Based on the flow-tube method,considering the pressure start-up gradient,it establishes an theoretical model to evaluate the areal sweep efficiency of five-spot and square inverse nine-spot well pattern,gets the relational expression between areal sweep efficiency and time/water cut,plot the curve of them and analyse the sensitivity of injection-production pressure,well space,oil viscosity and pressure start-up gradient to areal sweep efficiency.By considering the impact of gravity and inter-layer cross-flow,the paper establishes a evaluation model to evaluate longitudinal development effects,analyse the influencing factors of production and plot the permeability ratio plate boundary for hierarchical development.Through using the permeability ratio plate boundary to the development of QHD32-6 oil field,the paper compares the differences between hierarchical and commingle development.By applying the areal sweep efficiency evaluation model to QHD32-6 oil field,the paper analyses the relationship between sweep efficiency and time and water cut,and finally proposes some effective advice to enhance the sweep efficiency.The paper defines a new theoretical method to evaluate sweep efficiency of water flooded heavy oil reservoir,develops the evaluation method of longitudinal development effect and propose the permeability ratio plate boundary for hierarchical development so as to provide important theoretical basis and technical support for the development of multilayered heavy oil reservoirs. |
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