The present invention is directed to a system and method for determining the relative position of tubular members used in drilling for hydrocarbons. More specifically, in certain embodiments, to a system and method of determining the position of a hanging (suspended vertically by a crane, draw works or other device) drilling tubular member relative to a downhole tubular member to permit the automated alignment and makeup or breakout of said tubulars.
The drilling rig floor environment has historically been one of the more dangerous working environments. These activities exposed drilling personnel or “roughnecks” to a variety of health and safety concerns, including working on the catwalk or monkey boards high on the drilling rig derrick, hanging tubulars, power tongs and associated chains, hand injuries when aligning and lowering tubulars, not to mention risks associated with well control or other gases returned with the drilling mud. Early methods called for lifting tubulars on an elevator and manually positioning the hanging tubular to mate up with a tubular that was suspended in a rotary table (downhole tubular). In the context of the present invention, a “tubular” may refer to well casing, drill collar, drill pipe, production tubing, or other tubular members that are threaded together and utilized in the drilling and production of hydrocarbons. Traditionally, roughnecks were required to move tubulars from a tubular storage area, align the hanging tubular with the downhole tubular, lower the hanging tubular to come into contact with the downhole tubular and utilize hydraulic tongs to apply torque to “spin-up” the tubular, such that the threads in the downhole tubular engaged the hanging tubular and were tightened. The hanging tubular was then utilized as part of the drilling process. The tripping or removal of tubulars from a well, called for roughnecks to apply hydraulic tongs to breakout or disengage the threads between two sections of tubular, with the uppermost (hanging) tubular being moved by hoist to a rack or other storage area.
In an effort to improve safety, there have been a number of improvements in the above processes. Semi-automated tubular handling equipment has been used to move tubulars to and from a storage area to the drilling floor and in position for makeup. Automated torque wrenches, known as iron roughnecks, have been devised which, under control from the driller, advance toward a mated hanging and downhole tubulars to makeup or breakout the threaded tubular connections. Despite these advances, there remains the problem of alignment of the hanging tubular with respect to the downhole tubular. Current practices still require two or more roughnecks on the drill floor to align the hanging tubular with the downhole tubular before the driller can lower the hanging tubular and engage the iron roughnecks. Thus, drill floor personnel remain exposed to the dangerous drilling environment.
It is desirable to develop a system and method for determining the position of the hanging tubular relative to the downhole tubular, without human intervention on the drilling rig floor. It is further desirable to utilize the positioning information as input to automated pipe handling and positioning system to align the tubular and place their respective threaded ends into contact with each other prior to engagement of the iron roughneck when making up the tubulars. The same positioning information may be used to safely disengage the hanging tubular from the downhole tubular following breakout during tripping operations.