Modelling and applications of autonomous flow control devices
Eltaher, Eltazy Mohammed Khalid
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Inflow Control technology has been employed in long, horizontal wells completions since the early 1990s. Their introduction prompted the extension of reservoir and well simulators to support their modelling and optimisation. More recently, Autonomous Flow Control Devices (AFCDs) have further improved well performance. However, the impact of AFCDs on reservoir management cannot yet be confidently predicted since their (autonomous) discrimination and control of the different fluid phases presents new modelling challenges that require extension of today’s wellbore/reservoir models and workflows. Novel methods to visualise and optimise AFCD completions are also required. This thesis shows how to use widely available, commercial codes to reliably simulate wells completed with AFCDs. Workflows for the optimal design and quantification of the economic value of such completions have been developed. The resulting predictions are compared with published data (AFCD calibration curves). They are used to evaluate the AFCD-completions “added-value” for a range of reservoir types, device specifications and fluids. This work particularly addresses: i. Performance of the device - little published data on AFCD multi-phase flow performance is available. Also, commercial reservoir simulators provide just one equation to capture the underlying physics of all AFCD types. ii. Wellbore model - a representative reservoir/wellbore model and the previously ignored physics (stratified flow in the annulus and well trajectory alteration) are now essential since an AFCD’s performance is strongly fluid-sensitive. The above AFCD modelling and optimisation challenges are addressed by: 1) Developing an AFCD performance model that honours published data. Equations and modelling recommendations for several commercial AFCDs along with a range of modelling options, some novel and bespoke, are presented. The impact of uncertain multiphase flow performance on the AFCD well’s “Added-Value” is quantified. 2) Increasing the accuracy of commercial well/reservoir simulators when modelling AFCD completions by recommending how to model the well trajectory, the reservoir/well segmentation and the multiphase flow performance. 3) Comparing the performance of optimised AFCD- and ICD-completions in multiple reservoir models to illustrate how various reservoir management challenges can be met.