APPARATUS FOR APPLYING AN ELASTOMERIC SHEATH TO A WIRELINE USED IN OILFIELD SERVICE OPERATIONS

摘要

A slotted, continuous elastomeric sheath is applied to a wireline as the wireline and its instruments connected thereto are lowered into a plastic lined tubing within an earth borehole, the elastomeric sheath being used to prevent damage to the plastic coating on the interior of the tubing. The tubular elastomeric sheath is wound on a storage drum for transportation and the application of the sheath to the wireline. The sheath passes through a measuring sheave having a throat positioned at the wireline to be covered. As the sheath approaches the wireline, an orienting finger is used within the slot in the sheath causing the slot to open up. The opening also results from a natural consequence of the sheath being bent about a radius with the slot in the sheath oriented to the outside of the sheave throat. Idler rollers are provided to facilitate the alignment of the sheath with the wireline. The measuring sheave is also used to monitor the linear velocity of the sheath as it is being removed from the wireline. The linear velocity of the wireline is also monitored and compared with the velocity of the sheath. An electrical comparator circuit drives a variable speed motor to either increase or decrease the velocity of the sheath to provide a means for removing the sheath from the wireline at the same velocity as the wireline as it is being hoisted from the well bore. During the application of the sheath to the wireline, the drum upon which the sheath is wound is allowed to rotate freely without the use of the motor and the sheath pulled off the drum by the frictional forces between the sheath and the wireline.