Intelligent Well Completions
Authors: Robinson Mike 
Published: June 2014

Technology Today Series articles are general, descriptive representations that summarize the state of the art in an area of technology by describing recent developments for readers who are not specialists in the topics discussed. Written by individuals recognized as experts in the area, these articles provide key references to more definitive work and present specific details only to illustrate the technology. Purpose: to inform the general readership of recent advances in various areas of petroleum engineering.

The oil and gas industry is actively pursuing the implementation of remotely monitored and controlled well completions. This technology, collectively referred to as &#x0022;intelligent completions,&#x0022; has advanced rapidly over the last few years showing benefits including increased recovery and production acceleration. Savings from reduced well intervention provide further payback, particularly for multilateral, subsea, or unattended platform wells. Application of this technology has continued to expand rapidly because the value of these completions has been demonstrated in field installations.

Intelligent-completion installations are becoming widespread, with approximately 200 systems deployed. The concept uptake has increased during 2002 03 with 50 to 75 systems per year being installed. This level of application is expected to increase as the technology becomes widely accepted as field-proven.

Introduction

As Fig. 1 suggests, an intelligent completion may be defined as &#x0022;a completion system capable of collecting, transmitting, and analyzing wellbore production, reservoir, and completion-integrity data, then enabling remote action to enhance reservoir control and well-production performance.&#x0022; It should be noted that, currently, the concept of the intelligent completion does not refer to any capability for automated self-control or optimization, but relies on a manual interface to initiate commands to the well. Remote completion monitoring refers to the ability of a system to provide data, obtained in or near the wellbore, without requiring access for conventional intervention to the well. Remote completion control implies that command instructions can be transmitted to the well to alter the position or status of one or more flow control components. Normally, the drivers of intelligent completion are optimizing production and maximizing recovery and capital-expenditure efficiency while minimizing operating costs and safety hazards.

Currently, various systems are installed. Hydraulic motive power is dominant, although a variety of electric and hybrid electrohydraulic and optohydraulic completions have been deployed successfully.

History and Technology Development

Until the late 1980s, remote monitoring was generally limited to surface transducers around the tree and choke, remote hydraulic control of subsurface safety valves (SSSVs), and (electro-) hydraulic control of tree valves. The first computer-assisted operations optimized gas lift production by (remote) choke control near the tree and assisted with well monitoring and control of pumped wells. With the development, successful implementation, and improved reliability of a variety of permanently installed sensors, operators began to consider direct control of wellbore inflow to provide significant economic benefit. The service industry responded with high-level systems designed to provide full monitoring and control functionality.

Initially, intelligent-completion flow-control devices were based on technology used by conventional wireline-operated sliding-sleeve valves. These valves were reconfigured to provide on/off and variable-position choking by use of hydraulic, electrical, or electrohydraulic actuation systems. Further development resulted in choke devices resistant to erosion and configured for high-differential-pressure service. Additional equipment based on conventional SSSV technology provided in-line ball valves for on/off closure.

Initially, these fully integrated systems were not widely accepted because of the high incremental capital cost and perceived low possibility of success resulting in a high risked cost, which, at the time, did not meet project-screening criteria. To counter this challenge, lower-cost hydraulic systems were offered to provide some of the functionality of the initial high-end systems. These budget systems permitted packaging a variety of sensors together with hydraulic control devices to provide a composite intelligent-well completion.

Often, data-handling and transmission procedures left much to be desired and reflected the ad hoc nature of early installations with the proliferation of stand-alone PCs, basic production-monitoring systems, and consequential data overload. More recently, permanent downhole pressure and temperature gauges and intelligent completions were combined with some form of intranet or Internet data transmission, increasing speed and use of the data. Sensors were developed to measure flow rates by use of either nonintrusive systems or venturi meters. Combinations of these devices can be linked with additional fiber-optic systems to measure distributed temperature profiles, multipoint pressures, and acoustic signals (permitting the deployment of permanent seismic sensors). The performance lifetime of such systems was variable but is moving toward acceptable levels as suppliers invest in increased reliability engineering.

Intelligent-completion technology medium-term goals are summarized as follows.Prevent routine intervention for reservoir-management purposes.Leverage systems giving multiple horizon or reservoir penetrations per well.Self-optimize and automate wells and process facilities.Design processes on an optimum system rather than component basis (e.g., downhole/subsea vs. surface facilities and infrastructure).Intelligent-completion system reliability should exceed 95&#x0025; operability 10 years after installation.