Design of a New and Viscosity Independent Autonomous Inflow Control System

Abstract

Breakthroughs of water and/or gas in production wells may have direct consequences for the production rates and overall field recovery factors. Multiple technologies have recently been developed to autonomously control inflow from the reservoir. Common to all these technologies is that new limitations are introduced which may have a negative impact on the well. This paper presents the design process for the next generation inflow control system and introduces new requirements for such completions. Traditional Passive Inflow Control Devices (ICD) are designed to act in a preventive manner by setting up a somewhat more even inflow profile along the reservoir section and thereby delay the breakthrough of gas or water. More recently, several new initiatives have been presented which will operate autonomously and try to choke back unwanted production. Common to all these technologies is that viscosity differences are used to identify the flowing fluid phases. Viscosity differences between the reservoir fluids are therefore mandatory for these to work. In this work the design process has been given an operational focus and the following requirements for the next generation autonomous inflow control devices have been defined: easy to install as an integrated part of the downhole completionrobust in design and functionalitysecures complete clean-up of mud and completion fluidsindependent of fluid viscositynegligible pressure drop during normal productionallows back-flow of fluids In this paper a new design is proposed for the next generation autonomous inflow control valve which is independent on differences in fluid viscosities. The proposed valve blocks, or restricts, production of unwanted water or gas, and re-opens for production if oil comes back. It can be designed to stop water/gas production at a predetermined WC/GOR. Furthermore, the valve ensures efficient clean-up along the full length of the reservoir section and is insensitive to exposure to mud, particles and filtercake. The valve will not restrict any future well operations and can be designed with a fail-safe option. The new design of autonomous inflow control systems represents a great technological improvement which will ensure robust, economical and fail safe design as well as removal of typical operational envelopes necessary for traditional technologies.

A Novel Automatic Inflow-Regulating Valve for Water Control in Horizontal Wells

“…28 The floating ball AICD identifies fluids using the density difference of fluids, and it induces fluids into different channels; thus, water or gas control is realized. 29 The channel AICD has special flow pressure loss of an unexpected fluid is increased. 30−39 However, AICDs, which generate different pressure losses using density differences, cannot control water accurately because the effect of flowing fluids on movable components is not fully considered.…”

“…The switch state and opening degree of the floating flappers are completely determined by fluid density . The floating ball AICD identifies fluids using the density difference of fluids, and it induces fluids into different channels; thus, water or gas control is realized . The channel AICD has special flow paths that are suitable for different fluids and can induce different fluids into different flow paths; thus, the additional pressure loss of an unexpected fluid is increased. − However, AICDs, which generate different pressure losses using density differences, cannot control water accurately because the effect of flowing fluids on movable components is not fully considered.…”