Pressure performance of multi-stage fractured horizontal well considering stress sensitivity and dual permeability in fractured gas reservoirs

Abstract

Generally, the horizontal well multi-stage fracturing technology is widely used to enhance single well production of tight or ultra-low permeability gas reservoirs. The deformation of the rock pore structure makes the permeability of the reservoir impossible to be a constant. The pressure transient analysis mathematical model of the multi-stage fractured horizontal wells (MFHWs) with consideration of stress sensitivity, varying conductivity and dual-porosity dual-permeability (DPDP) is established. Laplace transformation, pressure drop superposition and Gaussian elimination are utilized to obtain the wellbore pressure solution of MFHWs. Comparison result reaches a good agreement by model validation. On the basis of pseudo-pressure derivative curve characteristics, eight flow regimes can be diagnosed, namely, well storage, skin affection, bi-linear flow, early linear flow, early radial flow, middle linear flow, inter-porosity flow and later radial flow regime. The influences of some vital parameters on pseudo-pressure and its derivative curve is discussed in detail. The proposed model can help engineers understand the pressure dynamic characteristic of the MFHWs with stress sensitivity, varying conductivity and DPDP performance.