Reaming While Drilling Downhole Drilling Device
Publication Date: 2004-Aug-31
The IP.com Prior Art Database
This article describes the idea of a downhole reaming device comprised of two motor sections connected that way that the lower internal rotor section drives the main hit and its housing contains steering mechanisms that allow the tool to be directed into a certain well path. The housing of the first power section is connected to the internal shaft of the second power section which eventually connects to the remainder of the BHA. The housing of the second power section is rotating when drilling fluid is pumped through it and a reaming device is attached to the housing which allows the enlargement of the hole that is drilled by the pilot bit. The reaming device can be expandable or fixed. Later will limit the enlargement of the hole to certain geometric combinations. The expandable reaming device will allow any reasonable enlargement diameter. If the second power section is designed to turn in the opposite direction of the first power section and the enlargement diameter is chosen properly it is possible to equalize the reactive torque output of the combined unit. This will have favorable implications for the steering process and eliminate unwanted torsional stick slip behavior of the drill string. The power sections shown the schematic are positive displacement motors of the moino principle but could be also any other hydraulic motor types (eg. Turbines or other positive displacement motors) . The drive mechanism does not require any drill string rotation for the drilling and reaming operation. If the steering section of the first unit is attached to the housing driving the system from surface should be done only in a non steering mode. If the steering section is arranged as a non~—rotating sleeve the system is steerable during sliding as well as rotating the drill string.