A critical requirement for directional drilling with coiled tubing (CT) is a reliable downhole means to manipulate the orientation of the mud motor bend. Alaskan operations have traditionally used hydraulically actuated ratcheting orienters, thus avoiding the complications of wireline and control lines inside the coiled tubing. With highly refined field techniques and well plans, the fundamental drawbacks to these orienters have been adeptly managed on the North Slope.

Despite good success over the years, drilling and orienting have remained mutually exclusive activities. As such, orienting becomes nonproductive time (NPT) when it cannot be combined with necessary hole conditioning and wiper trips. While orienting problems and failures have been increasingly common in deep and high-build-rate applications, perhaps the most significant challenge to the standard hydraulic orienter service for coiled tubing drilling (CTD) is lost circulation.

Initial steps in the development of an intelligent wireless orienter for CTD were taken in 1999 with the goal of eliminating off-bottom orientation, a significant source of NPT for Prudhoe Bay operations. Subtle computer-controlled mud pump variations are the basis for a versatile downlink command structure used to drive the downhole actions of the turbine orienter. The benefits of the prototype orienter were confirmed during a promising field trial beginning in late September 2001. As of December 2001, the novel service has been used on eight wells in Prudhoe Bay. This paper describes the turbine orienter development program, testing, a quantification of benefits, reliability figures, lessons learned, and future plans.

You can access this article if you purchase or spend a download.