Analytical modelling of wells with inflow control devices.

Abstract

Inflow Control Devices (ICD) have been successfully used in hundreds of wells around the world during the last decade and are now considered to be a mature well completion technology. This work is dedicated to the methodology of making following three decisions with respect to ICD application: 1. Selection between ICD and Interval Control Valves (ICV), the other advanced completion technology. 2. Identification of whether particular well is likely to benefit from ICD. 3. Quantification of the anticipated positive effect. Design of an advanced completion for a particular field application often includes feasibility studies on both ICV and ICD. The choice between these two technologies is not always obvious and the need for general methodology on making this choice is recognised by the petroleum industry. In this dissertation ICD has been compared against the competing ICV technology with particular emphasis on issues such as uncertainty in the reservoir description, inflow performance and formation permeability. The methodology of selection between ICD and ICV is proposed. The benefits of ICD application can, by and large, be attributed to reduction of the following two effects detrimental to horizontal well performance: Inflow profile skewing by frictional pressure loss along the completion (heel-toe effect). Inflow variation caused by reservoir heterogeneity. Frictional pressure drop along the completion is an important design factor for horizontal wells. It has to be taken into account in order to secure optimum reservoir drainage and avoid overestimation of well productivity. Many authors have previously addressed various aspects of this problem, but an explicit analytical solution for turbulent flow in wellbore has not so far been published. This dissertation presents such a solution based on the same assumptions as those of previous researchers. New method to quantify the reduction of inflow imbalance caused by the frictional pressure loss along a horizontal completion is proposed. The equation describing this phenomenon in homogeneous reservoir is derived and two solutions presented: an analytical approximation and a more precise numerical solution. Mathematical model for effective reduction of the inflow imbalance caused by the reservoir heterogeneity is also presented. The trade-off between well productivity and inflow equalisation is a key engineering issue when applying ICD technology. Presented solutions quantitatively addresses this issue. Their practical utility is illustrated through case studies.