The High Expansion Wedge; Accessing A New World Of Coiled Tubing Drilling Sidetracks Through An Innovative Casing Exit System Approach

Abstract

Coiled Tubing Drilling (CTD) has been used on the North Slope of Alaska (Fig. 1) since 1994 for drilling sidetracks or laterals. Technology and techniques developed in Alaska have been transferred globally including the process and best practices to mill windows off whipstocks. A majority of the through tubing sidetracks have been drilled using conventional monobore or through-tubing whipstocks in multiple configurations. CTD has been limited to the size of the tubing or minimum internal diameter (ID) that a whipstock can pass-through and the ID of the tubing, liner, or casing that the whipstock will be set in. A 3-1/2" Thru-Tubing whipstock has a running outer diameter (OD) of 2.625" and could only be set in liner or casing up to 5-1/2". The problem with installing a 3-1/2" Thru-Tubing whipstock in larger liner or casing than 5-1/2" has always been the ability to properly anchor the whipstock and keep the window milling bottom hole assembly (BHA) on the tray of the whipstock. That is no longer an issue with the development of the High Expansion Wedge (HEW). The HEW has a 2.625" OD and is capable of anchoring inside 7" liner or casing. This type of whipstock will open a new set of CTD candidates that have previously been inaccessible. The goal of this paper will be to describe the design, testing, and field trials that were used to develop the HEW.