Pressure transient analysis of a horizontal well intercepted by multiple non-planar vertical fractures

• A new fracture wing model has been established to model the non-planar fractures.
• The flow regimes of a horizontal well intercepted by infinite and finite conductivity fractures have been identified.
• The effect of NPA, fracture spacing, wellbore storage on the pressure response has been discussed in detail.

The principal focus of this work is on pressure behaviors of a horizontal well intercepted by multiple non-planar fractures. The non-planar fractures can be obtained by combinations of multiple wings with varied non-planar angle (NPA) and length. In theory, the bilinear flow regime, first linear flow, first radial, biradial flow and the pseudo radial flow regime can be identified for coplanar multi-fractured well. However, in practice, the shorter fracture spacing makes the biradial flow absent. The results of our investigation indicated that NPA mainly affects the first linear flow when CfD>1 and the bilinear flow when CfD≤1. As the NPA increases, the pressure depletion enlarges. However, the impact of NPA on pressure depletion is not linear relation. When NPA<50°, the change of relative derivative pressure (RDPC) is less than 5%. The characteristic straight line corresponding to the flow regimes can be identified approximately. When NPA=70° and 80°, it reaches 10% and 20%, respectively. In this case, the NPA exerts strong influence on the pressure derivative curve and the formation linear flow cannot be observed even at high fracture conductivities. It is shown that for small value of the wellbore storage CD, it will not affect the existence of flow regimes just delay the occurring time of characteristic flow regimes. For bigger value of the CD, the wellbore storage may conceal the early flow regimes and the bilinear flow and first linear flow may be no longer observed. Meanwhile, the effect of NPA on pressure weakens.