Abstract

New developments in drilling tubulars are rapidly evolving and represent enabling technologies for the industry's continued advancement of drilling deeper, longer reach wells more cost effectively. This paper presents key tubular technologies including metallurgical and manufacturing advancements that have enabled high strength, high toughness drill pipe. Application specific landing string designs that provide substantial advances versus conventional designs are presented and analyzed. Field performance of 5-7/8 in. drill pipe is also presented.

Introduction

Intermediate sized 5-7/8 in. drill pipe has eliminated previously perceived limitations in extended reach drilling (ERD) and deepwater projects. Since late 1999, over 40 drill strings of 5-7/8 in. drill pipe have been manufactured and put into the field. The drill pipe has been successfully used to drill ERD, deepwater and ultra-deep HPHT wells in the South China Sea, Gulf of Mexico (GOM), Caspian Sea, Offshore Trinidad, Onshore Wyoming and Onshore Colombia. The 5-7/8 in. drill pipe has improved penetration rates and significantly shortened drilling curves.

Metallurgical and manufacturing technology advancements have yielded the development and reliable production of high strength drill pipe grades up to 150,000-psi yield strength combined with attractive fracture toughness properties. These grades provide longer reach and deeper well depths while maintaining valuable set back capacity.

The increasing requirements to land heavy casing strings in deepwater environments has generated tubular design challenges that have been met with “out of the box” designs including thicker wall slip sections, double diameter tool joints and high strength thin body walls. These state-of-the-art landing strings reduce weight requirements on the rig and improve efficiency in both running and cementing operations.

5-7/8 in. Drill Pipe

The engineering philosophy and design of 5-7/8 in. drill pipe has been previously documented in the industry literature.^1,2,3 To summarize, 5-7/8 in. drill pipe is an intermediate drill pipe size that is dimensionally optimized for the majority of casing designs and bit programs involved in ERD, deepwater and ultra-deep wells. 5-7/8 in. drill pipe reduces bore pressure losses by approximately 28% when compared to 5-1/2 in. drill pipe and does not suffer from the increased running and handling requirements associated with 6-5/8 in. drill pipe. Unlike 6-5/8 in. drill pipe, when 9-5/8 in. casing is set, 5-7/8 in. drill pipe may be used within the 8-1/2 in. hole section, effectively reducing the rig's drill pipe inventory from the common dual OD tapered string of 6-5/8 in. X 5-1/2 in. to a single OD string of 5-7/8 in.

These performance benefits were key reasons for the development of 5-7/8 in. drill pipe, but how has the pipe performed in the field since its inception?

Field Performance Overviews

Since October 1999, over 835,000 ft of 5-7/8 in. eXtreme™ Reach (XR) XT57 drill pipe has been manufactured and put into service. The mix of 5-7/8 in. manufactured has been in three wall thicknesses: 73% (613,000 ft) has been the standard 23.40 lb/ft (0.361 in. wall) product, 26% (214,000 ft) has been the thicker walled 26.30 lb/ft (0.415 in. wall) product that was designed to provide the same tensile capacity as 6-5/8 in. 27.70 lb/ft S-135 drill pipe and 1% (10,000 ft) has been thick walled (0.750 in. wall) landing strings used to run heavy deepwater casing strings.

The customer base for 5-7/8 in. drill pipe has evolved with time. Initially, the product was marketed and sold to rental tool companies predominantly in the GOM region. Realizing the performance benefits of the 5-7/8 in., a number of operators then pursued direct and indirect purchases mostly for international project-specific drill strings. This is an interesting aspect considering operators do not traditionally purchase drill pipe and is further evidence of the product performance benefits to the end user. The most recent addition to the customer base is the purchase of 5-7/8 in. by drilling contractors, without any direction from operators, as a means to improve the performance and marketability of their rigs. Figure 1 depicts the customer base mix in each of these three categories.