Patent Application
20150275594
The field of the invention is a slip carrier insert for a rotary table of a drilling rig and more particular where the slip carriers are integrated into a frame to fit a non-circular shaped opening in the rotary table.
Drill strings are usually supported by spiders that fit in the opening of the rotary table. They usually have a slip bowl in which slips are peripherally distributed to surround the pipe to be gripped. The slip bowl opens upwardly. When a pipe string suspended in the well is to be gripped by the spider, the slips are moved downward. The slip bowl surface urges the downwardly moving slips to move radially inward to bear upon, and grip, the pipe. When the slips grips the pipe and load is transferred, the resulting downward force adds to the radially inward thrust of the slips, and largely defines the essential elements of what has become known as a failsafe system. Teeth carried by the slips contact the pipe to improve pipe security. The teeth may be on detachable dies that are carried by the slips.
Spiders are currently sold as an assembly which is inserted into the rotary table opening. Considerable design and engineering work has gone into the slip manipulation gear related to spiders. The spider housing, in effect, duplicates the function of the rotary table structure.
Larger tubulars, such as casing, are usually handled by spiders that rest on the rig floor above the rotary table. Such spiders are often capable of serving as elevators. The novel slip carriers and slip powering apparatus of this invention can be applied to such spider structures with minimum preparation.
Slips have to be secured to retain, or control, their peripheral distribution within the slip bowl. The slip control structure and slip manipulation gear makes up a considerable part of the usual spider. Such a composite spider can often function with minor, or no, adaptation as an elevator. In some cases, there is no way to distinguish a spider from an elevator.
Spiders and elevators, in many cases, have no power actuators and are strictly manual in operation. When composite spiders are prepared by the manufacturer for use in the field, they have limited adaptability to function for a variety of pipe sizes and, if considerable diversity of use is planned, several spiders have to be on hand or readily available. There is a need for spider sub-assemblies that can be fitted into rotary tables, or related structure, to enable adaptability. There is also a desire to have these spiders and sub-assemblies easy to disassemble, maintain, and replace. Current spiders are found in U.S. Pat. No. 7,891,469 B1, U.S. Pat. No. 3,748,702 A, U.S. Pat. No. 3,579,752, and U.S. Pat. No. 7,143,849 B2. They are purpose built to a specific size and not readily adaptable to different pipe sizes or rotary table openings.
The present invention is modular with the slip housings being integrated into the assembled shape. Dies on slips can be changed to accommodate various pipe sizes with minimal effort. The unit can be assembled around a tubular. These and other aspects of the present invention will be more fully understood by those skilled in the art from a review of the detailed description of the preferred embodiment and associated drawings while recognizing that the full scope of the invention is to be determined from the appended claims.
A spider can be made from several individual segments, that when configured together will fit in the non-circular recess drive of a rotary table. The spider will fit loosely into the rotary table so that any loads can be transferred directly to the rotary table recess. A mounting structure will serve to hold the non-continuous parts of the spider together until it is placed in the rotary table. The non-continuous peripherally distributed parts of the assembly have a slip manipulation surface which slopes downward toward the vertical center line of the rotary table. On each surface a slip will travel, so that when the slip moves down, it also radially constricts. With upward motion the slip radially expands. The slips also have a changeable set of dies to allow quick and easy adaption to different size pipes. The slips are powered by a linear motor in both directions. This will allow for powered radial movement in both directions. The slips will be timed together so that they contact and evenly apply pressure on the pipe being gripped. At least one section of the spider and timing ring may also be easily removed so that a pipe can pass through at least one of its sides. By making some of these parts identical, manufacturing and inventory can be reduced.
a show a perspective view of a complete assembly as it goes into the rotary table and an enlarged view of an alignment dovetail;
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The assembly 109 is made up from slip carriers 5 and 9 and intervening mounting structures 1 and 11. The slip carriers 5 and 9 and mounting structure 1 and 11 are held together by a T-Slot 57, where slot surface 205 and 101 restrict each other. These t-slots can be formed in different orientations. Other methods of removable joining can be used such as bolts or pins. The pipe 15 is fixed by the dies 8 or 7 depending on the size. When in use all the dies would be the same size but in
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Those skilled in the art will appreciate the unique advantages of the present invention. The guides for the slips are integrated with the top of the frame to transmit torque from the gripped pipe directly into the rotary table opening. The slip guides are an integral part of the top of the frame at its corners and slip into contact with intermediate connecting pieces. This type of mounting allows resizing of the frame for different rotary table sizes by substitution of the corner pieces or the connecting pieces or both. Torque from the gripped pipe goes into the corner pieces that support the slip guides directly as opposed to a separate ring structure that caps the slip guide support members shown in U.S. Pat. No. 7,891,469. Links pivoted on opposed ends connect the slips to the timing plate to convert the axial movement of the timing plate into radial movement of the slips into the pipe along slanted guides such as a dovetail.
The frame has a base and spaced members that are interconnected with connecting members to define a segmented ring that has a top surface in preferably a single plane. The interconnecting members have at least one that is longer than the pipe to be grabbed so that the segmented ring can be partially assembled and slipped over a pipe and then completed. The connection between the spaced members and the interconnecting members can be of a projection and depression combination of surfaces. The spaced members support slip guides and have a surface that contacts a wall that defines the opening in the rotary table. The slip guides a sloped and the slips ride on the guides connected with a pivoting link from an operating ring that is segmented and moves the slips in tandem with hydraulic pistons so that axial movement is translated to radial movement of the slips that have a die on the grip face for gripping the pipe without damage. The dies can be replaced with other dies of different sizes to handle different pipe diameters in the same frame structure. The segmented ring size can be easily changed with replacing the spaced members or the interconnecting components or both to handle different sizes of rotary tables with minimal part inventories.
The above description is illustrative of the preferred embodiment and many modifications may be made by those skilled in the art without departing from the invention whose scope is to be determined from the literal and equivalent scope of the claims below:
