Lengthening drill string containing an instrument

摘要

A pipe section is added to a drill string while an instrument and a flexible line leading to the instrument remain in the string. The effective length of the flexible line is increased in corresponding with the increase in length of the drill string by connection of the flexible line to a carrier by which the line is carried in a coiled condition occupying a distance longitudinally of the drill string shorter than the actual length of the line. The carrier is constructed to pay out the different turns of the coiled line successively from coiled condition to a straightened condition in a manner progressively increasing the effective length of the line. Preferably, the line is paid out from the carrier by pulling the carrier toward the outer end of the drill string while an inner end of the line is connected to the instrument in the string. The pulling force may be applied to the carrier through a second flexible line which is detachably connectable physically to the carrier and electrically to the first mentioned line and preferably extends through a circulating fluid head.