Abstract: A whipstock mill for milling through the casing wall which incorporates a pressure drop tattletale to signal the operator that the milling operation should be halted. The milling tool includes a longitudinal fluid passageway which communicates with a lateral port formed below the mill blades. A replaceable plug is utilized to initially close the port thereby restricting fluid flow into the well hole. The starter mill is preferably run into the hole with a whipstock which can be set in the hole using an integral packer. As the mill travels down the set whipstock, a shear block mounted to the whipstock will shear the plug at a predetermined depth of the mill opening the lateral port. The resulting pressure drop within the milling tool signifies that the mill has reached the desired depth. Accordingly, the milling operation can be halted and the mill retrieved to permit further operations through the casing wall.

Abstract: A method of cutting and retrieving submarine well casing which includes the steps of lowering a tool on a string into the bore of the well casing which tool includes a casing cutter, a bumper sub connecting from the cutter to the combined anchor swivel and latching means to retain the anchor in unset position when it is being run with the string connected to the upper end of the tool, landing the tool with the swivel supported on the upper end of the casing and the remainder of the tool within the casing, releasing the latching means, raising the string to set the anchor, tensioning the string, energizing the cutter arms, rotating the string to cut the casing, and raising the string to retrieve the cut casing. The apparatus includes a casing cutter, a bumper sub, a combined anchor swivel and latching means to retain the anchor in unset position which latching means is actuated to unlatched position by manipulation of the string on which the tool is supported.

Abstract: An anchor which includes a tubular body, a top closure and a bottom closure secured to opposite ends of said tubular body, a plurality of drilling cutters mounted on the bottom closure, a neck having an external groove therein secured to the top closure, an opening in both the top and bottom closures, means for coacting with a drill string extending into said closures for sealing to maintain the interior of said body substantially free of water when submerged, a ratchet collar adaped to coact with a mating ratchet collar of the drill string for rotating the anchor to cause it to drill into the bottom of a body of water, a swivel adapted to be lowered onto the neck of the top closure when it has been set, latching dogs engaging in the external groove to secure the swivel to the body, and floatation means for signaling the surface that the swivel is set.