Reliability in ICS* Intelligent Completions Systems: A systematic Approach from Design to Deployment
Authors: Veneruso A.F. , Sharma S. , Vachon G. , Hiron S. , Bussear T. , Jennings S. 
Published: October 2008

Intelligent completion systems integrate reservoir sensors and remotely controlled devices deployed permanently in the wellbore. They minimize intervention and optimize reservoir production. Reliability is paramount, as the downhole devices must operate over many years while inaccessible for maintenance or repairs. The system is more than the sum of its valves and sensors. It encompasses many links, from the formation to the customer's desktop, and any of these can fail and each of these is critical to the system. This paper presents an innovative approach to intelligent completion systems reliability based on reliability growth testing as part of the engineering development process. The first step is identifying the key links in the chain to find all potential weak points and their impact from the user's viewpoint. This is crucial in that it involves components from many providers: the completion, subsea pod, umbilical, platform and data management system. It is accomplished through a process analogous to triage in emergency medical care. Once the critical points are identified, experiments are designed to expose them to stress conditions that accelerate failure mechanisms. This provides data about the expected reliability of the component and identifies the most likely failure modes. The results of this analysis and testing are fed back into the design process to strengthen the system against failure. Common failure modes are also identified as a prerequisite for design redundancy. Finally, field experience shows that the reliability of the deployed system depends strongly on the installation process because it introduces the highest potential failure modes. To address this issue, intelligent completion systems benefit from the experience of hundreds of permanent monitoring installations made to date and from the close coordination between field and engineering personnel that ensures successful installation through reliable designs and techniques. Offshore wells, especially in deep water, are likely to have increasingly complex geometries as high-tier multilateral techniques develop and mature. Intelligent completion systems will be needed to produce such wells cost effectively, and achieving long, reliable lifetimes will require a systemic approach throughout the entire engineering, manufacturing and deployment cycle.

Introduction

Worldwide demand for oil and gas is expected to increase 2.5% per year from the anticipated production of 74 million BOPD for 1997. Even if the increase in consumption is limited to 2.2% per year, two-thirds of the world's available reserves will have been consumed by 2007. To meet this rising demand, it is necessary to establish new reserves, which in turn implies aggressive exploration programs undertaken in deeper waters than ever before. Not surprisingly, rig utilization and day rates are near an all-time high. Because oil prices have not increased, operators are looking at reducing their cost drivers for well construction, accelerating production, minimizing workover and intervention costs, and increasing the recovery factor from their fields. Industry initiatives aimed at reducing key operating times by 1999 are evidence of this trend. These fundamentals will most likely continue in the foreseeable future, and new technology such as intelligent completions will play an important part in reducing the cost per barrel of oil produced.