Mainbore connectivity in perforated whipstock multilateral wells

Abstract

The Starburst Multilateral is a special type of the TAML level 4 junction built around the proven concept of the hollow technology. This hollow technology has been in use in the North Sea for the past ten years and there have been significant improvements in this tool allowing for high pressure capability before and after milling the window. An innovative concave geometry protects the concave face during milling operation and after drilling the lateral, the liner is installed and cemented across the junction before the hollow whipstock and liner is perforated to regain production.

As of date, most of Statoil wells in the Gullfaks area are in their latter stages of production, since the Gullfaks field is a typical mature field. This has led to the challenges of wells producing at low rates; however these rates are not lower that what can be delivered by an alternative use of the slot. Thus one solution to these challenges is employing the Starburst multilateral technology to maintain production from the old well while gaining inexpensive access to new drainage points.

This thesis describes the Starburst multilateral technology and the special tools used for it’s installation at various Statoil wells in the North Sea, with details on challenges with connectivity at the junction after perforation of whipstock, concluding with significant findings, discussion and possible solution to the challenges.