Research On Interwell Swept Dynamic Regulation Of Step-by-stepProfile Control For Fractured Ultra-Low Permeability Reservoir

Water injection is the main method to achieve effective exploitation and long-lasting stability for fractured ultra-low permeability reservoir.However,because the matrix is compact and natural fractures are developed,the fractures will stretch during water injecting.Some complicated channeling system is easy to form between water injiecting wells and oil production wells.that will cause sevaral water cut and then sharply reduce the development effectiveness.Now,multi-slug step-by-step profile control has been one of most effective methods for fractured ultra-low permeability reservoirs.In this paper,tracer interpretation models including single peak type,multi-peak type and wide platform type corresponding to three types of water channeling fracture system were established by converting complicated heterogeneous problems into relative homogenization conditions based on the basic principle of inter-well tracer explanation and analyzing the injection-production system water channeling and flooding characters of fractured ultra-low permeability reservoir and,which can effective characterize inter-well sweep state parameters of water channeling and flooding of fractured ultra-low permeability reservoir.Based on previous inter-well tracer explanation parameters,well group production dynamic parameters and static parameters,time-domain chemical tracking analysis method of fractured ultra-low permeability reservoir was established by using BP neural network forecast technology,which achieved tracer explanation parameters to change and be predicted with times.Then profile control parameters were introduced in time-domain chemical tracking model,and time-domain chemical tracking neural network analysis method for step-by-step profile control of fractured ultra-low permeability reservoir was established by adopting multistage inter-well chemical tracking technology to extract multistage tracking monitoring sample during the process of profile control,which studied the influence law of fracture belts permeability ranges and profile control parameters on inter-well sweep state for step-by-step profile control based on relative parameters reflecting inter-well sweep state such as newly increase sweep volume magnification,distribution coefficient of injected water,pressure gradient magnification,pressure drop filling rate magnification,yields increase rate and so on.Research and experiment results showed that time-domain tracking analysis method for step-by-step profile control could effectively feedback inter-well sweep dynamic for step-by-step profile control of water channeling and flooding of fractured ultra-low permeability reservoir,and provided an effective and practical method for scheme optimization design for step-by-step profile control of water channeling and flooding of fractured ultra-low permeability reservoir,real-time dynamic monitoring and profile control effect prediction.But as a new method,it still needs to strengthen field data acquisition and analysis,extent continuously different types of samples and improve gradually the accuracy of time-domain tracking neural network method for step-by-step profile control,and eventually be consistent with real situation of field.