Horizontal and multilateral completions are a proven, superior development option compared to conventional solutions in many reservoir situations. However, they are still susceptible to coning toward the heel of the well despite their maximizing of reservoir contact. This is due to frictional pressure drop and/or permeability variations along the well. Annular flow, leading to severe erosion "hot-spots" and plugging of screens is another challenge. Inflow Control Devices (ICDs) were proposed as a solution to these difficulties in the early '90s. ICDs have recently gained popularity and are being increasingly applied to a wider range of field types. Their efficacy to control the well inflow profile has been confirmed by a variety of field monitoring techniques.
An ICD is a choking device installed as part of the sandface completion hardware. It aims to balance the horizontal well's inflow profile and minimize the annular flow at the cost of a limited, extra pressure drop. Fractured and more heterogeneous formations require, in addition, the installation of annular isolation. The new technologies of Swell Packers and Constrictors can provide this annular isolation in an operationally simple manner.
This paper describes the history of ICD development with an emphasis on the designs available and their areas of application. These technical criteria will be illustrated using published field examples. The ICD's flexibility will be shown by its integration with other conventional and advanced production technologies e.g. Stand-Alone-Screens, annular isolation, artificial lift, gravel packs and intelligent completions in both horizontal and multilateral wells.
It will be shown how the value of such well-construction options can be quantified using commercially available, modelling simulators. Simple, but reliable, guidelines on how to model the performance of ICDs over the well's life will be provided. This technique can thus be used as part of the value quantification process for both the evaluation of completion options and for their detailed design.
1 Introduction
Horizontal and multilateral wells are becoming a basic well architecture in current field developments. Advances in drilling technology during the past 20 years facilitated the drilling and completion of long (extended reach) horizontal and multilateral wells with the primary objective of maximising the reservoir contact. The increase in reservoir exposure through the extension of well length helped lower the pressure drawdown required to achieve the same rate and enhance the well productivity 1–2. Major operators have proved the advantages of such wells in improving recovery and lowering the cost per unit length. The production from thin oil column reservoirs (e.g. The Norwegian Troll Field) became a reality thanks to such wells 3–4.
However, the increase in wellbore length and exposure to different reservoir facies came at a cost. Frictional pressure drop caused by fluid flow in horizontal sections resulted in higher drawdown-pressure in the heel section of the completion, causing an unbalanced fluid influx. Hence, coning of water and gas toward the heel of the well was observed. Variable distribution of permeability along the wellbore also results in variation of the fluid influx along the completion and an uneven sweep of the reservoir.
Annular flow is another challenge often encountered when horizontal wellbores are completed with Stand-Alone-Screens (SAS) or with pre-perforated/Slotted liners. Neither of these completion options employs any form of isolation between the casing and the formation (i.e. external casing packers). Annular flow, which is dependent on many parameters such as the size of the clearance between the sandface and the liner (screen) outer diameter, still imposes several problems including: dislodging of the sand grains causing erosion of the sandface, formation of "hot-spots" and plugging of the sand screens 5–6. Previously, the elimination of such phenomenon required the utilization of gravel packs or installation of Expandable Sand Screens (ESS), which often had a significant impact on the well productivity and/or involved a very complex operation 6–7.
