Intelligent Multilaterals: The Next Step in the Evolution of Well Construction (2002)

Abstract Over the last ten years there have been thousands of multilateral wells drilled in almost every energy market and geological basin of the world. During the same period wells that can be monitored downhole and flow controlled have increased in popularity and application. It is natural that these two technologies should meet and start a new family of wells known as "intelligent multilaterals." The benefits of multilateral technology and controllable completions have been well documented. The ability to access and control multiple reservoirs from a single parent wellbore can have significant effects on the economics of hydrocarbon recovery. These include higher production rates, greater total production, controlling/minimizing water and/or gas coning, greater reservoir understanding, and minimizing well and facilities construction costs. Multilateral wells give better reservoir accessibility than "monobore" designs from both a well construction and a reservoir drainage standpoint. From a well construction standpoint it is better to have laterals going out of a mainbore to make room for the completion and control assemblies. Multilateral well designs also provide much more flexibility in reservoir drainage architectures by allowing the well to "branch out" from a single, linear wellbore design. The type of intelligent completion and multilateral technology deployed depends on many factors, such as junction isolation, completion type, mechanical accessibility, and the resolution and amount of control required. The use of electric, hydraulic/electric, or all hydraulic-actuated flow control equipment can enhance flexibility, well operability, and reservoir management. From simple to complex, these two technologies can be combined in a myriad of ways to offer solutions in many types of environments. This paper will present a compendium of applications, including technology that is available today and concepts for the future that are being considered by the industry. The benefits and drawbacks of various potential solutions will be evaluated, and examples of intelligent completion equipment with respect to multilateral installations will be discussed. The Impact of Intelligent Completions The ability to access and control multiple reservoirs from a single parent wellbore can have a significant effect on the economics of hydrocarbon recovery.1 This positive impact can be identified through higher production rates, through greater total production or ultimate recovery, by controlling or minimizing water and/or gas coning, by shutting off zones with water or gas encroachment, through greater reservoir understanding, and through minimizing well and facilities construction costs. Higher production rates can be obtained through the implementation of intelligent completion technology. These production rates can be obtained through the installation of intelligent artificial lift equipment (e.g., gas lift valves 2), by switching producing intervals as the zones begin to deplete 3 or by optimizing inflow from multiple points along a horizontal section.4 An increase in ultimate recovery can be obtained from the ability to switch production between multiple zones or from allowing production to continue after water or gas encroachment. 5 This is accomplished by turning off the offending zones, facilities limitations of gas or water production do not hinder production.