| The production of tight oil has grown rapidly in recent years,and 2017,the production of shale oil and tight oil had reached162.?10~8bbl in United States.The development of tight oil is slow in our country,but the potential is large.Due to the extremely low permeability and porosity of tight oil reservoirs,the study of the imbibition is very pop.The energy storage during shut-in schedule after fracturing is based on imbibition,and it has achieved success.However,the concept of energy storage is new,people don't have a clear understanding of it.So it is important to study on the shut-in process after fracturing,and reveal the stimulation mechanism of energy storage,in order to provide suggestions.Based on numerical simulation,this paper uses reservoir numerical modeling software Petrel RE to establish the fracture network model of a single fracturing stage,and a single well model.They are used to simulate the fluid flow and pressure diffusion process of fracturing fluid in the fracture network scale.And analyze the changes of pressure during shut-in.Meanwhile,the effect of fracturing fluid volume,formation pressure and permeability on energy storage are studied.And the influence of production after energy storage is also studied.It is concluded that the shut-in after fracturing accelerates the diffusion and pressure propagation of the fracturing fluid,enhances the pressure transfer and mass transfer between fracture and matrix,increases the imbibition rate and volume,and increases the matrix pore pressure.It has the function of energy storage and displacement.The pressure and area can be used to characterize the effect of energy storage.The complexity of fracture network,the amount of fracturing fluid,the shut-in time are the main factors affecting the shut-in effect.The shut-in time cannot be determined by the wellhead pressure drop,but is determined by the time required for fracturing fluid imbibition and oil-water replacement in the matrix pores.In order to improve the energy storage effect,the complexity of the network can be improved and the fracturing can be changed.Optimized shut-in time are also important.Energy storage after fracturing is mainly applied to reservoirs with low water saturation and sufficient imbibition power.Finally,the successful application of the energy storage in the field,it shows that the energy storage in shut-in schedule is useful.And a method to optimize the parameters of the volume of fracturing and time of shit-in.At the same time,the single well model is used to fit the change of bottom hole pressure during shut-in. |
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