In consideration of the matrix-crack-wellbore coupling flow and matrix-wellbore coupling flow in an open-hole fractured horizontal well in low/ultra-low permeability reservoirs,mathematical models were derived on the basis of the equivalent flowing resistance method and the superposition principle.For an open-hole fractured horizontal well,the flow field was divided into three regions according to the different flow mechanism: Darcy flow in artificial fractures,low-velocity non-Darcy elliptical flow in the ...