DE-FC26-02NT41662

Goal: Improve the rate-of-penetration in deep hostile drilling environments by improving the life cycle and performance of coiled-tubing and/or drill-pipe.

Objectives: The primary objective is to develop an efficient and economically viable continuous microwave process to sinter continuously formed/extruded steel powder for the manufacture of seamless oilfield tubular products. The performance of seamless pipe manufactured in this manner is expected to be superior to that of pipe manufactured using conventional processes. Phases I and II of the three-phase research program will demonstrate the feasibility of the proposed concept and develop a prototype, continuous microwave-sintered, tube manufacturing system. Phase III will include scale-up, field-testing, and commercialization of the system.

Performers:
The Pennsylvania State University – Project management and all research products
Dennis Tool Company – commercialization partner
Quality Tubing Inc. – commercialization partner

Accomplishments: This research project involves the adaptation of an existing technology (powder metallurgy, a highly developed method of manufacturing metal parts) to the manufacture of high-performance drilling tubulars. The powder metallurgy process involves the mixing of metal powders with a suitable lubricant, applying pressure to the mixture in a mold to create a part with the proper dimensions, and heating the object so that the powder particles weld together (sintering). Research has shown that the use of microwave energy makes it possible to sinter materials at a lower temperature and shorter time than required for conventional methods, minimizing grain growth, and retaining a grain structure that results in better mechanical properties in the finished part.

Conventional coiled tubing is manufactured by forming a tube from strip steel and welding the seam with an electric welding process. The seam remains a weak point in the tubing, subject to fatigue, corrosion, and possible failure under high pressures. This project is focused on developing an efficient process for the manufacture of seamless tubing with superior mechanical properties by adapting and improving PM processes.

The first year of the project has involved a demonstration of concept feasibility as part of Phase I. Achievements have included:

• Conducted a preliminary study to identify the microwave sintering conditions that would produce the highest density values for a stainless steel-molybdenum alloy (316L) with high strength and corrosion resistance properties. The results showed that nearly full density was achieved at 1340 °C for 10 minutes.
• Modified a continuous sintering microwave system developed for an earlier DOE project and tested it on cylindrical samples (1 inch diameter and 1 inch height) of alloy FN208 (Fe:97.2, Ni:2.0,C:0.8). Vertically continuous sintering at the optimum sintering temperature for FN208 yielded samples with a uniformly consistent density.
• Successfully fabricated and sintered longer tubular samples (~12 inches long, 1 inch diameter) of 316L steel powder.
• In collaboration with the Indian Institute of Technology, (Kanpur, India), developed a modified 316L composition that included oxide dopants (yttrium aluminum garnet) to further improve strength and corrosion resistance, and performed conventional sintering experiments to determine mechanical properties.
• Collected information related to design options for a continuous extrusion and microwave sintering system capable of producing tubing at rates consistent with a commercial enterprise.

The extrusion of powdered metal into tubes in a manner that will support continuous sintering will require the development of unique techniques that combine continuous extrusion of a tubular shape and continuous microwave sintering. Through collaboration with Japanese researchers at National Institute for Fusion Science (NIFS), PSU has been able to identify a 25-ft long continuous microwave-sintering kiln for prototyping in Phase II. PSU is currently working out the details for building a similar system in State College or at Dennis Tool’s facility.

The fabrication of the continuous horizontal Microwave sintering unit is nearing completion. The system is capable of processing tubes of diameter up to 3.5 inches. This project is to develop a process to extrude powdered metal through an extruder and sintering the green metal using microwave energy to manufacture oilfield tubulars (continuous coiled tubing and jointed pipe) that will have superior qualities than current manufactured tubulars. Tooling for the extrusion testing at Loomis Products Company in Levittiwn, Pa has been purchased for a one inch tube shape. Green extruded solid rods and tubes have been extruded. There has been some problems with slumping and twisting of rods during tempering and is being investigated. Coatings of carbon material either sprayed or painted on the rod/tube appear to be the solution.

Once the above feasibility has been demonstrated the primary task of Phase II will be scaling up and marrying these two systems (extruder and microwave kiln) so that continuous fabrication and sintering of tubulars with specific properties can be accomplished.

Project Start: September 27, 2002
Project End: July 31, 2006

DOE Contribution: $1,350,000 (all three Phases)
Performer Contribution: $720,000 (all three Phases)

Contact Information:
NETL – John Rogers (john.rogers@netl.doe.gov or 304-285-4880)
The Pennsylvania State University – Dinesh K. Agrawal (dxa4@psu.edu or 814-863-8034)