7/29/2019 DC Mar07 Eickhoff

1/156 March/April 2007 D R I L L I ND R I L L I N G C O N TRA C TO R

D O W N H O L E T O O L S

Titanium-based hardbanding aims to balance

protection for wear in casing, tool joints

OVER THE PREVIOUSdecade, average well depthshave increased, and directional and extended-reach drilling

have become commonplace. These wellbore trajectories, withtheir highly tortuous paths and the associated increases intorque and drag, have placed stresses on drill pipe. They havealso created conditions of accelerated wear on both the drillpipe and casing never encountered to the degree we see in theindustry today, due to the higher side loads associated withthese deep tortuous well bores.

Lead times on new drill pipe orders of 12 months or moreare not uncommon, and pipe costs have risen dramati-cally in recent years. Drill pipe strings with large tube ODor heavy wall thickness and premium connections run inexcess of $1 million. These conditions have made it neces-sary to investigate means to prevent wear to the drill pipe

and to increase the useful life of this critical, high capitalcost asset.

Hardbanding in the oilfield has long been acknowledged as aneffective means of preventing wear to the tool joints. Howeverin the early 1990s, the DEA-42 study proved that the tungstencarbide-based hardbanding in widespread use at the time wasthe primary cause of wear to the casing. Furthermore, thestudy proved that the absence of hardbanding, while slowingcasing wear to a very small degree, allowed the tool joints to

wear at an extremely accelerated rate and thus rapidly losetorsional capacity.

The problem, then, is balancing the need to protect the casing

from wear and simultaneously protecting the tool joints fromthe increased wear conditions present in high KOP (kick-offpoint), deviated, extended-each and horizontal wells. The firstcasing-friendly alloys introduced in the 1990s reduced the cas-ing wear problem, but eventually field service history conclud-ed that either they wore at an unacceptable rate or their met-allurgy was so designed that they cracked excessively, causingcatastrophic tool joint failure, or the hardbanding itself faileddue to the material completely disbonding (spalling) from thetool joint, which left sharp ridges and edges that can causecasing wear. This condition can leave large quantities of hardmetal in the well.

The problem to solve then includes:

Low casing wear within industry limit determined by DEA-42testing.

Highly durable to resist wear and protect the tool joint.

Crack-resistant to prevent cracking in the material and tooljoint.

Disbonding (Spall) resistant.

Unlimited ability to resurface / reapply the material withoutspecial conditions.

Ability to reapply in the field in remote and adverse condi-tions.

In 2004, National Oilwell Varcos Tuboscope introduced the

TCS Titanium. Titanium carbides on their own are approxi-mately 40% harder than tungsten carbide while simultaneouslyexhibiting crack resistance and a slippery smooth microstruc-ture, which prevents metal pick-up in metal-to-metal applica-tions. The titanium carbides are uniformly distributed through-out a chrome-martensitic alloy matrix. This combinationprovides a balance among casing wear potential, high stressabrasion resistance, crack resistance and weldability.

This is a super-refined hardbanding alloy, manufactured asa self-shielding, flux cored, open arc wire. The open arc / selfshielding type wire was chosen so the material could be appliedin any field location in the world, even where shielding gases arenot available or the quality is suspect. This means that the TCS

Titanium can be applied in a plant, or the field / rig site if needed.

An ASTM G-65, Standard Test Method for Measuring AbrasionUsing the Dry Sand / Rubber Wheel Apparatus test, was per-formed on the TCS Titanium. It showed a 3 -time increase in

wear resistance over chrome alloy and chrome carbide materi-als. In addition, 14 separate laboratory metallurgical evalua-tions were performed on the material to determine crackingsusceptibility, spalling resistance, overlay capability, determine

welding parameters (WPS), SOP procedures, weldability, andgenerate Procedure Qualification Records.

To date, over a half-million joints have been hardbanded withTCS Titanium.

Tuboscope and TCS are registered trademarked terms.

By Stacy Eickhoff, Tuboscope NOV

The TCS Titanium hardbanding has shown a 3 -time increase in

wear resistance over chrome alloy and chrome carbide materials.