As a result, the drill string
used by HDD for the pilot hole was selected to be used as the casing.
Considering that only several types (such as [N.sub.T] in (19)) of drill strings
are manufactured, [d.sub.tub] distributes discretely.
Some techniques are available to reduce drill string
The drill strings
were now tripped back and advanced to the south platform in order to create a continuous drill string
"Straighter holes relate to correct and appropriate drill strings
and good control of thrust (or bit load), but this has nothing to do with computer control."
Among the tools needed for less-costly scientific superdeep drilling and sampling are long-life hard-rock drill and core bits; special core drilling technology for recovering a significant percentage of core; the use of hollow shaft downhole drilling and coring motors for improved core recovery, increased penetration rates, and reduced fatigue and stress in long drill strings
; advanced automation for drill pipe handling and tripping equipment; improved methods for borehole trajectory control; more sensitive monitors placed near the bit for early deviation detection, and downhole instruments to monitor core and drill bit performance.
"We're getting positive feedback from users who say the tool is helpful, especially being able to file and reference drill strings
Plunkett, "Static bending stresses in catenaries and drill strings
," Journal of Engineering for Industry, vol.
In April 2008 Heerema Marine Contractors Australia signed a contract with Woodside Energy as operator, on behalf of Australia's NWSV (North West Shelf Venture), for the transport and installation of the North Rankin B Platform substructure and topside, and approached FSCL to tender for the design and build of two large pile top drills and three complete drill strings
for the jacket installation works.