Powered Capstans
Description
Ideally, wireline cable should be spooled off the drum and back onto the drum at the same tension. However when the wireline is coming up-hole the line tension is much greater than when it is going down-hole. The Powered Capstan is positioned between the hole and the main winch to handle the main hoisting work. This allows constant tension between the capstan and the main winch drum. A controlled target tension on the main winch is delivered regardless of which direction the cable is running.
The Power Capstan can give up to 9,000 lbs hoisting assistance which allows standard winch units to be used beyond their normal operating range and removing the need for custom winches. The Powered Capstan automatically maintains a screen selected "TARGET" tension on the main winch with the cable running in either direction. The Powered Capstan thereby eliminates “cable crush” on the drum.
A typical 4,000 lbs target can be maintained on the winch whether the actual well tension is 13,000 lbs when hoisting, or only 200 lbs when running cable down-hole into the well.
The system is fully automatic and controls synchronize the movement of the capstan and the main winch as determined by winch operator. The system allows speeds up to 300 ft/min and can run multiple tools.
The capstan can be used either secured to the horizontal deck or supported vertically in the derrick by the elevators.
The capstan is designed for minimal maintenance needs. The steelwork has 10-year corrosion protection.
The entire units is a 3-part lift, all with DNV 2-7.1 certification. The capstan and power pack are both rated Zone 2.
