The Development of an Infinitely Variable Choke for Intelligent Well Completions
Authors: Williamson Jim R. , Bouldin Brett , Purkis Dan 
Published: October 2008

Abstract
State-of-the-art completion technologies to more efficiently support the needs of the oilfield continue to be developed. For example, intelligent completion techniques, which are designed to allow the operator to reconfigure well architecture without well intervention, have gained a great deal of attention because of their capabilities to improve monitoring and overall well performance in multi-zone oil and gas field developments. In all of these multi-zone intelligent-well completions, flow adjusting and monitoring devices or interval control valves are located between zonal isolation packers to control flow into or out of each zone.
The first generation of these interval control valves was a choke that offered only four positions. To overcome the position limitations, an infinitely variable choke has now been designed. The requirements for this next-generation interval control valve provided many design challenges. This paper describes the design, development and testing of a metal-tometal sealing, infinitely variable downhole choke with true position sensing capability. All topics from the conceptual design and customer requirements to accelerated erosion testing and component life predictions will be discussed. Testing has verified that the new interval control valve can support the needs of the multi-zone well completion.

Introduction
The development of a surface controlled reservoir analysis and management system (SCRAMS?intelligent completion system) that would provide intelligent well capabilities began in 1994. The completion system was based on use of a permanently installed electrical network to transmit data and control a number of downhole well tools. Among the first downhole tools that were developed for use with the new system was the four-position interval control valve (ICV). With a limit of only four positions, the four-position ICV allowed for only full open, closed, and two intermediate choke positions. In addition to the limited choice of positions, the size of the flow ports for the intermediate choke positions had to be selected far enough in advance to allow time for manufacturing of the equipment.1
Almost immediately, it was obvious that the four-position ICV's would not be adequate to fulfill the promise of the greatly enhanced well control that the new intelligent well concepts were capable of providing. As a solution, the idea for an infinitely variable interval control valve (IVICV) was conceived. The IVICV was a joint project between two service companies that based the choke requirements on intelligent well as well as operator needs. The valve that was subsequently developed was capable of addressing the need for a downhole fully adjustable choke that could be operated with a SCRAMS controlled sensor actuator module (SAM?unit). Each zone of a multizone well can now have an individual sensor actuator module and an IVICV for adjustable flow control with pressure and temperature feedback to the surface. Fig. 1 is a schematic drawing of the IVICV.
Basic Operational Concept of SCRAMS Intelligent Completion System and the IVICV