Performance of Autonomous Inflow Control Completion in Heavy Oil Reservoirs
Authors: Eltaher Eltazy Mohammed Khalid , Sefat Morteza Haghighat , Muradov Khafiz , Davies David 
Published: May 2016

Inflow control devices (ICDs) are a proven technology of increasing reserves by passive control of the influx of fluids into the well. Experience with ICD completions shows that, although they may initially balance influx along the horizontal completion, they often do not offer the optimal solution throughout the well life due to the changing reservoir properties (pressures, fluid saturations and flow rates). Furthermore, the well completion design normally has to be designed prior to drilling the well. This, and the inevitable reservoir uncertainty, results in the ICD completion design being less efficient. A control device which adapts to the unexpected inflow performance autonomously can bring a distinctive advantage.

The recently introduced Autonomous Inflow Control Devices (AICDs) favour oil rather than gas and/or water inflow. AICDs can be installed as frequently at 12 m intervals along the completion wellbore. The Autonomous Inflow Control Valve (AICV), a flow control technology that can be designed to virtually shut-off unwanted fluid inflows, takes this unwanted fluid mitigation strategy one stage further.

This paper uses reservoir simulation to examine the concept of heavy oil/water production control in advanced Well Completions (AWCs) containing ICDs, AICDs and AICVs. Their performance has been analysed in a range of models to address the effects of heterogeneity, pressure losses and reservoir configuration. Both similar and very significant differences in incremental oil production were achieved between these down-hole Flow Control Devices (FCDs).

This paper also developed an oil/water flow modelling workflow for reservoir and well engineering studies by quantifying the value added by the optimal use of this new, down-hole completion technology, providing preliminary completion selection guidelines. Completions that combined the widest range of proactive reactive performance, such as AICVs, were found to be the most efficient at shutting-off unwanted fluid production.

Introduction to Advanced Well Completions

AWCs employing ICDs provide a proven solution to several reservoir management issues by controlling the flow between the well and the reservoir along the wellbore. The technology was first introduced in the North Sea in the mid-1990's (Madsen, 1997) to drain oil via long, up to 2500 meters, horizontal wells placed in a ~ 13 meter oil rim reservoir. They improved reservoir drainage and increased oil recovery. They have since become a commonly applied technology for draining heterogeneous and heavy oil reservoirs as well as for the management of water allocation in injection wells.

A wide range of commercial FCDs is available that significantly differ in their design, configuration and flow performance. FCDs currently include ICDs, Interval Control Valves and Autonomous Flow Control Devices (AFCDs).

AFCDs, the latest development in flow control technology, add phase selectivity to the passive ICD's performance by autonomously creating an additional flow restriction to unwanted fluids. AFCD technology is currently in the rapid development phase with several new ideas being proposed; e.g. two new concepts employing different physical principles have been introduced in 2014 {Sang et al., 2014) and (Zeng et al., 2014}. The earliest AICDs have passed the proof of concept stage and become commercially available; while others are still in the engineering development phase (Eltazy et al., 2014).