Wells – With electrical means – Indicating
Reexamination Certificate
2001-12-12
2003-09-30
Dang, Hoang (Department: 3672)
Wells
With electrical means
Indicating
C166S077520
Reexamination Certificate
active
06626238
ABSTRACT:
CROSS REFERENCES TO RELATED APPLICATIONS
None
STATEMENTS AS TO RIGHTS TO INVENTIONS MADE UNDER FEDERALLY SPONSORED RESEARCH AND DEVELOPMENT
None
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an apparatus for installing pipe in a wellbore, such as an oil or gas well. More particularly, this invention relates to an apparatus for determining when movable elevators in a drilling rig are properly positioned relative to a section of pipe to be installed in a wellbore. More particularly still, this invention relates to an apparatus which can provide a signal when elevators, and more specifically the slips of such elevators, are positioned at a desired location relative to a section of pipe to be installed in a wellbore and, conversely, when such elevators and slips are not so positioned. More particularly still, the present invention relates to an apparatus which can be used to prevent elevator slips from being closed when such elevator slips are improperly positioned relative to a section of pipe to be installed in a wellbore.
2. Description of the Related Art
Standard rotary drilling rigs are typically comprised of a supportive rig floor, a derrick extending vertically above said rig floor, and a traveling block which can be raised and lowered within said derrick. During drilling operations, such rig equipment is often used to insert and, in some cases remove, tubular goods from a well situated under such derrick. For example, drill bits and/or other equipment are often lowered into a well and manipulated within such well via tubular drill pipe. Moreover, once a well has been drilled to a desired depth, large diameter pipe called casing is often installed in the wellbore and cemented in place in order to provide structural integrity to the well and to isolate downhole formations from one another.
When installing casing, drill pipe or other pipe into a well, such pipe is typically installed in a number of sections of roughly equal length. These pipe sections, often called “joints,” are typically installed one at a time, and screwed together or otherwise joined end-to-end to make a roughly continuous length of pipe. In order to start the process of inserting pipe in a well, a first joint of pipe is lowered into the wellbore at the rig floor, and suspended in place using a set of “lower slips.” Such lower slips are often wedge-shaped dies which can be inserted between the outer surface of said pipe and the bowl-like inner profile of the rotary table. Such lower slips hold the weight of the pipe and suspend the pipe in the well. Although such lower slips can be automated, in many applications such lower slips are manually inserted and removed by rig personnel.
During the process of installing pipe into a well, a first joint of pipe is generally inserted into a well and positioned so that the top of said joint of pipe is located a few feet above the rig floor. A rig crew or a pipe handling machine grabs a second joint of pipe, lifts said second joint of pipe vertically into the derrick, positions said second joint above the first joint which was previously run into the well, and “stabs” a male or “pin-end” thread at the bottom of said second joint into a female or “box-end” thread at the top of the first joint. The second joint is then rotated in order to mate the threaded connections of the two joints together.
Thereafter, a set of elevators attached to the traveling block in the rig derrick is typically lowered over the top of the second (i.e., upper) joint of pipe. Such elevators have a central bore which is aligned with the uppermost end of the joint of pipe. The pipe is received within the central bore of the elevators. Once the elevators have been lowered over the pipe a desired distance, slips within such elevators can be activated to latch or grip around the outer surface of said joint pipe. Depending on the length of the second joint of pipe, this can often occur 40 feet or more above the rig floor.
Once the elevator slips are properly latched and engaged around the body of the pipe, the traveling block and elevators can be raised to take weight off of the lower slips. The lower slips can then be removed. Once the lower slips are removed, the entire weight of the pipe string is suspended from the elevator slips. The pipe can then be lowered into the well by lowering the traveling block. After the second or upper joint of pipe is lowered a sufficient distance into the well, the lower slips are again inserted in place near the rig floor. The process is repeated until the desired length of pipe (i.e., the desired number of joints of pipe) is inserted into the wellbore. This same process is typically utilized for many different types and sizes of pipe whether small diameter drill pipe or large diameter casing.
At certain points during this process, the entire weight of the pipe is being held or suspended by the elevators and, more specifically, the elevator slips. This pipe can be very heavy, especially when many joints of large diameter and/or heavy-wall casing are being run into a well. Accordingly, it is extremely important that the elevator slips must be properly latched around the uppermost section of pipe in the derrick to ensure that such pipe remains securely positioned within said elevators. If the pipe is not properly secured within such elevators, it is possible that the pipe could drop or fall out of the elevators, thereby causing damage to the rig or the well, or injury to rig personnel.
In many cases, a female or box-end threaded connection of a joint of pipe includes an “upset,” whereby said connection has a larger outer diameter than the rest of the pipe body. In other instances, pipe joints are joined together using internally threaded couplings; such couplings also have a larger outer diameter than the remainder of the pipe body. In either case, care must be taken to ensure that elevator slips, which are designed to engage against the outer surface of a pipe body (as opposed to the coupling or connection upset), are indeed aligned with said pipe body. If such elevator slips are inadvertently closed against a coupling or connection upset, such slips likely will not fully contact or engage against the outer surface of the pipe. This is true even when such slips are partially aligned with a connection upset or coupling. As a result, slips (including elevator slips) which are not properly engaged against a pipe body may not grip such pipe securely. If the slips do not grip the pipe securely, such slips may not be able to support the weight of the pipe string, and the pipe can fall out of the slips.
In one common method of installing or running casing into a wellbore, a worker is stationed on a platform in the derrick at approximately the height where elevator slips are closed on the top of a section of pipe, which can often be approximately forty (40′) feet or more above the rig floor. The worker, often referred to as a “derrick man,” visually observes when the elevators have been properly lowered over the top of a section of pipe and positioned relative to said section of pipe. The driller, who is located on the drill floor, controls the vertical positioning of the traveling block and the elevators attached thereto. Once the derrick man observes that the elevators are properly positioned relative to the body of the section of pipe (that is, that the elevator slips are not positioned adjacent to a connection upset or external coupling) the derrick man typically uses shouts or hand signals to communicate this fact to the driller. The elevator slips are then latched around the body of the pipe. Thereafter, the driller can pick up on the traveling block thereby lifting the entire weight of the pipe. In some cases, this positioning of the elevators relative to the uppermost section of pipe is determined or confirmed using one or more closed-circuit video cameras mounted in the derrick which can provide a video image of such elevators to personnel located on the rig floor or at other locations on the rig.
It is often very dif
Anthony Ted M.
Dang Hoang
Offshore Energy Services, Inc.
LandOfFree
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