Implementation of an Advanced Multi-Lateral System With Coiled Tubing Accessibility
Authors: Antczak E.J. , Smith D.G.L. , Roberts D.L. , Lowson Brent , Norris Robert 
Published: December 2007

Abstract
This paper describes the design requirements for the development, and the field experiences gained in the successful installation of the world's first through tubing, selective lateral access system installed by an operator in Rotterdam Field, in The Netherlands.
The project goals included the development, testing and field deployment of completion equipment which would:permit selective coiled tubing access into any of several lined laterals of a well bore, for reservoir management, maintenance, and stimulation, andspecifically allow the installation of flow control devices within the lateral.
The lateral access system (or "access sleeve") was specifically designed and test-verified to positively orient and latch within newly developed "pre-milled" casing window technology. Well RTD-14 was drilled and the main bore cased, using an oriented, "pre-milled" casing window in the 7" liner. A drilling whipstock was oriented to the "pre-milled" window, and secured into the orienting latch coupling. A 4-3/4" lateral was drilled from the casing window, and lined with 3-1/2", and mechanically tied-back to the main bore via the casing window system's tie-back hanger. The whipstock was retrieved and the access sleeve was oriented, latched and isolated above and below utilizing the same casing window system's integral orienting latch coupling and integral seal bore subs. Using coiled tubing (CT) and running through drill pipe to prevent excessive buckling, a re-entry whipstock device was inserted into the access sleeve. A plug was then run on CT across the whipstock, out the access sleeve, and into the lateral liner without resistance. The plug was set within a landing nipple of the lined lateral. The plug and whipstock were then retrieved using CT. The access sleeve was temporarily retrieved from the casing window system in order to perforate the lower zone with tubing conveyed guns. After perforating, the access sleeve was successfully reinstalled, properly oriented and secured into the casing window latch coupling. Finally, 3-1/2" completion tubing, and the upper wellhead were installed.
Problems occurred during installation of this first combined "pre-milled" casing window plus access sleeve system. The problems were successfully dealt with to fully meet the project objectives. Equipment design modifications were identified for improvements to the installation and operation of the combined systems.
Many applications of multi-branched wellbores are expected to require total lateral access for conducting routine maintenance, production monitoring, stimulation, and flow control or flow regulation. Reliable through tubing access becomes another tool for cost effective reservoir management for the operator. This new technology will provide flexibility in the future design and operation of complex drainage architecture wellbores.
Cost effective intervention in complex drainage architecture wells are a reality, provided as a result of the development of new technologies. Contributions are specifically a result of three key technical innovations.
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