Sr. Ospicara

IADC/SPE 112560
A Case History of Casing Directional Drilling in the Norwegian Sector of the
North Sea
Kevin Bourassa and Tove Husby, ConocoPhillips Company Norge AS; Rick Watts, ConocoPhillips; Dale Oveson,
Tommy Warren, Tesco Corp; Hans Magnus Bjoerneli, Bill Lesso, and Frode Sunde, Schlumberger

Copyright 2008, IADC/SPE Drilling Conference
This paper was prepared for presentation at the2008 IADC/SPE Drilling Conference held in Orlando, Florida, U.S.A., 4–6 March 2008.
This paper was selected for presentation by an IADC/SPE program committee following review of information contained in an abstract submitted by the author(s). Contents of the paper have not
been reviewed by the International Association of Drilling Contractors or the Society of Petroleum Engineers and aresubject to correction by the author(s). The material does not necessarily
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Abstract
In January 2007, ConocoPhillips completed what is believed to be the first well directionally drilled with casing using
wireline retrievable bottom holeassemblies from an offshore installation. ConocoPhillips has considerable experience with
this technology in reducing drilling days on predominately vertical land wells in South Texas. It was desired to determine if
the same benefit could be realized in the offshore environment; where directional drilling is required. A candidate
development well was identified in Norway on the ConocoPhillipsoperated Eldfisk Bravo platform that could benefit from
advantages seen with Casing while Drilling. Two land based tests were conducted to confirm the ability to conduct casing
directional drilling in wells similar to those expected in Norway. Simultaneously, a detailed plan for drilling the well in
Norway was developed.
Two production casing strings (10 ¾-in. and 7 ¾-in.) were successfully drilleddirectionally through the overburden section
on the Eldfisk well. The well had a complex 3-dimensional well path with inclination up to 60°. All running and retrievals
of the BHAs was planned to be done with wireline and a purpose-built traction winch system rated to a working load of
40,000 lbs. Once the 7 ¾-in. production casing was cemented, the casing string was converted to a productionliner with an
expandable liner hanger and the upper section of 7 ¾-in. was retrieved. In all, 10,968 ft of the 13,600 ft well was
directionally drilled with casing.
Introduction
ConocoPhillips has actively used Casing while Drilling (CwD) technology in more than 150 wells in South Texas since 2001.
This technology has contributed to solving downhole problems associated with lost circulation andsloughing shales. 1,2 It
has been a factor in providing excellent hole conditions. From a well control standpoint, CwD technology is advantageous in
that it provides the ability to circulate the entire time that the BHA is being pulled or run into the well with wireline. This
leaves the pipe at or very near to bottom during the drilling process; even with the BHA out of the well. All of thesefactors
have allowed COP to significantly reduce trouble time and overall days required to drill wells in areas of South Texas. While
there have been some directional CwD applications on land, the technology was not proven in the offshore environment. An
obvious question for COP was “Can the benefits seen using CwD technology on onshore vertical wells be realized in the
offshore environment...