The Interporosity Flow Behavior Between Matrix And Fracture In Tight Oil Reservoirs Due To Pressure Difference

The tight oil reservoirs,which contain a large amount of micro-scale natural fractures,are often developed with stimulated fractured method so that there is complex fracture network in the formation.The interporosity flow between matrix and fracture is neglectable for tight oil reservoirs.Furthermore,huge difference about percolation environment exists between conventional and tight reservoirs for nano-and micro-throats are developed in the tight formation.The seepage characteristic and parameters about pore and throats need to be described again.It is significant for recognizing the seepage principle to describe the interporosity flow,the matrix flow and fracture flow accurately.Firstly,the distribution of pore throats is extracted according to experiment data and is characterized.In combination with the micro-tube experiment,the thickness of the boundary layer has been obtained.Based on the micro-tube model,the effective permeability expression has been got by considering the pore-throat distribution and boundary layer effect;the permeability expression for fractures with different size and different shape has been derived.Secondly,through the methods of reservoir engineering,the interporosity flow models are built for contact between matrix and hydraulic,natural fractures;the average pressure is used to describe the matrix-fracture interporosity flow;the flow correction factor is used to describe the unsteady interporosity flow with higher precision.the flow rate,cumulative flow volume and correction factor are obtained.Finally,different influential factors(matrix permeability,boundary layer,viscosity,pressure difference,fracture spacing)to flow rate are analyzed under different contact model between matrix and fracture.The pressure curve and plot are obtained.The flow equation of matrix and fracture and the interporosity flow model are got.The results have positive effect for recognizing the flow principle and directing the production of tight oil reservoirs.