A new, accurate and simple model for calculation of productivity of deviated and highly deviated well - Part I: Single-phase incompressible and compressible fluid

In this study, a three-dimensional mathematical simulator has been developed to investigate the single-phase flow behaviours around a deviated well. A large data bank of well productivity was generated, covering a wide range of variations of pertinent parameters, including the well length and angle, wellbore radius, reservoir dimensions, anisotropy, fluid properties and velocity. Using the results from the in-house simulator result, based on these results, the approach recently proposed for predicting horizontal well productivity [11] was extended to develop a general method, which can be applied to both horizontal and deviated wells placed in isotropic or anisotropic formations and flowing under either Darcy or non-Darcy flow conditions. In this method, the complex flow behaviour around the three-dimensional (3-D) deviated/horizontal wells is replicated by an equivalent open hole. The impact of pertinent parameters is quantified in terms of a skin or, in another form, an effective wellbore radius of the equivalent open hole. This new correlation is easy to use, no numerical simulator is needed and a quite simple spreadsheet can be used to provide an accurate estimation of the horizontal/deviated well productivity in gas and oil reservoirs.