Study On Evaluation Method Of Dynamic Connectivity In Low Permeability Reservoir

Efficient development of low permeability reservoirs occupies an important position in China's energy strategy.However,the identification of interwell connectivity has always been a difficult problem that restricts the effect of water injection development.At present,dynamic and static methods considering single factor are mostly used to evaluate connectivity,but they all have the problems of low recognition accuracy and difficult to make clear judgments.This paper tries to find an accurate and effective method to evaluate the dynamic connectivity of low permeability reservoirs.Firstly,the dynamic connectivity of the selected block is evaluated by three methods: production dynamic analysis,tracer monitoring analysis and oil-water distribution characteristics analysis.The comparative analysis shows that the factors considered by the three methods are different,and there are uncertainties in the identification of connectivity.Then,through the analysis of injection-production curve,it is found that the fluctuation of injection volume will not immediately cause the response of fluid production,but there are delays and attenuations.Considering the characteristics of delays and attenuations and analogizing the charging process of capacitors,a new resistivity-capacitance model suitable for low permeability reservoirs is derived.At the same time,the influence factors of dynamic connectivity in low permeability reservoirs are systematically analyzed by numerical simulation method.Next,according to the reservoir characteristics of different reservoirs,three numerical simulation models of homogeneous,high permeability channel and anisotropy are established,which verify the accuracy of the three mathematical inversion model methods.Finally,the new resistancecapacity model is applied to Wuliwan low permeability reservoir,and the result of dynamic connectivity evaluation with high accuracy is obtained.Through production dynamic verification,the recognition result of the model is accurate and conforms to the actual situation of the reservoir.The new resistance-capacity model established in this paper provides an effective method for dynamic connectivity identification of low permeability reservoirs.It provides an important basis for the implementation of measures to increase production and has application value.