Reverse Circulating Junk Basket (RCB) is a junk retrieval tool designed to remove all types of objects from the bottom of the well bore. This superior tool removes such items as slips, hand tools, bit cones, and any other small pieces of junk from the well. The RCB uses reverse circulation to aid junk recovery.
The tool consists of a top sub, barrel assembly, catcher, and shoe. The barrel assembly consists of an inner and outer barrel, valve seat, cup, and ball. A lift sub is also provided to assist in handling.
Assembly and Operation
Make up the junk basket to the bottom of the string and run into the hole. When the tool is approximately 10 feet from the bottom of the hole, the ball is dropped down the drill pipe. The ball will position itself in the ball seat and reverse circulation will begin. Circulate and begin coring. Combined with the reverse circulation, this guarantees that any junk on the bottom is pumped into the barrel and caught by the catcher assembly. The tool is removed from the hole after cutting 10 to 20 inches of core.
Optional Components and Accessories
Shoes - Four types of shoes are available to fit the Reverse Circulating Junk basket.
Type A mill shoe is supplied as standard equipment with the cutting teeth dressed with hard metal and has side wings. The type A mill shoe is used where the formation is relatively soft and the fish is a loose piece.
Type B mill shoe is equal in design to the type A shoe; however it is hard faced with Gotcoloy a sintered tungsten carbide in an extremely tough matrix, which will effectively and rapidly mill up junk during the fishing operation. This shoe will cut on O.D., I.D. and bottom.
Type C mill shoe is also hard faced with Gotcoloy, however, is designed with a flat bottom, and the Gotcoloy is placed on the inner face and the outer face. This design is used to mill up junk and is extremely effective for cutting cores.
Type B or type C Gotcoloy dressed milling shoes are used if the formation is hard or if the fish is embedded in the formation. Use of these two designs also cuts away protruding excess metal to allow free entry of the junk into the basket.