Challenging Drilling Applications Demand New Technologies
Authors: Jellison Michael J. , Chandler Raymond Brett , Shepard Jeff 
Published: February 2016

This paper provides an update on recent developments and highlights some problem areas associated with the latest generation of extreme drilling applications. Deepwater, extended-reach (ER) and ultra-deep (UD) wells dictate large spread rates that can benefit from reduced tripping times. In response to this need, a third generation, ultra-high torque rotary shoulder connection has been developed incorporating a double-start thread that reduces assembly time by 50%. Any discussion of drill stem requirements for world-class UD and ER would be incomplete without consideration of advanced material technologies (carbon fiber based composites, Titanium and Aluminum) and their potential for enabling deeper and longer objectives. The strengths and weaknesses of each material relating to its use for drillpipe for critical applications are presented in this paper. Proper hardband selection, application and maintenance are essential to successfully and safely drill world-class UD, ER and deep-water projects. Essential features of hardband systems for critical applications are highlighted.

With water depths increasing to over 10,000 ft, offshore well depths exceeding 34,000 ft, and extended-reach targets pushing out over 35,000 ft, operators are setting larger diameter and heavier casing. These heavier casing strings require landing strings with setting capacities approaching 2-million pounds that have extended the limits of previous tubular manufacturing and handling capabilities. The paper describes the technology advancements required to develop and field implement an ultra-high capacity landing string system. The industry's advancement has led to an increasing trend of drill stem friction heating failures. The paper includes characteristic features of these failures along with case histories and prevention methods. High-speed telemetry (wired) drillpipe has been successfully deployed in critical drilling environments. The paper provides an update on this exciting technology and reviews recent case histories.

Deeper Targets and Faster Drilling with New Connection Technology

In today's rig market, deep-water, extended reach and ultra-deep wells dictate large spread rates that can benefit significantly from reduced tripping times. These same wells often have mechanical and hydraulic load requirements for which today's high torque connections may not be specifically optimized.

In response to this need, the development of a third generation, ultra-high torque rotary shoulder connection is now complete.1

One of the primary philosophies employed during the development of this new double-shoulder connection was the concept of "one size does not fit all" or "one design does not fit all." Drill pipe sizes were grouped into four different size categories. Design requirements for each group were prioritized and four different connection design configurations were developed to meet the specific and different needs of each drill pipe size.

The thread form is a double-start thread that reduces the number of revolutions to assemble the connection by half, see Figure 1. Double-start threads incorporate two threads spaced 180 degrees apart reducing the number of turns to assemble the connection by 50%, all other things equal. Conservative estimates suggest that the new connections will save approximately 7-1/2 hours in planned trip time per 20,000 ft well. The thread form also provides a unique dual-radius thread root that offers a step change improvement in fatigue resistance.

API tool joints are produced with specified minimum yield strength (SMYS) of 120,000 psi.2 Capitalizing on advancements in metallurgy and heat treatment techniques for high strength/high toughness steel grades, the new connection employs 130,000 psi SMYS tool joints. The new connections provide increased mechanical and hydraulic performance compared to previous generation high torque connections while also providing fatigue performance greater than standard API connections.3

These connections can facilitate more challenging wells, provide increased cost savings and reduce risk during the well construction process.