Patent Application
20160115741
Rig skidding apparatus and method.
It is often desirable to move drilling rigs short distances between wells within a drill site. Disassembling the rig and reassembling it at the new location is time and labor intensive, and increases the rate of wear of some rig components. To avoid disassembly and reassembly, one solution has been to skid the rig structure across steel framed rig matting. However, the force required to overcome the metal-to-metal sliding friction between rig and track was problematic. Other solutions have included sliding the rig on rollers and using rig walkers.
It is desired to achieve a means of moving a rig structure to a well site without requiring extensive disassembly of the rig structure that is labor and time efficient.
In one embodiment, there is disclosed a method of skidding a rig structure, comprising raising the rig structure; after raising the rig structure, placing a skid track under the rig structure, wherein the skid track comprises a low friction plastic sheet; lowering the rig structure onto the skid track; and sliding the rig structure along the skid track. The low friction plastic sheet may be supported by a base and the skid track may comprise a cooperating sheet, for example a continuous flexible metal sheet, placed between the plastic sheet and the rig structure. In one embodiment, there is disclosed a method of skidding a rig structure comprising placing beams in a position to support the rig structure; using jacks to raise the beams; raising the rig structure with the jacks; placing a skid track under the rig structure; lowering the rig structure onto the skid track; removing the jacks and the beams; and sliding the rig structure along the skid track, wherein the skid track comprises a low friction plastic sheet.
In various embodiments, there may be included any of the following features: upon sliding the rig structure to a desired location, placing beams in a position to support the rig structure; using jacks to raise the one or more beams, raising the rig structure with the jacks, removing the skid track from under the rig structure, lowering the rig structure and removing the jacks; sliding the rig structure along the skid tracks may occur by towing; the low friction plastic sheet may be a lubricant filled plastic sheet; the low friction plastic sheet may be self-lubricating; and the low friction plastic sheet may be ultra-high-molecular-weight polyethylene.
These and other aspects of the device and method are set out in the claims, which are incorporated here by reference.
Embodiments will now be described with reference to the figures, in which like reference characters denote like elements, by way of example, and in which:
Immaterial modifications may be made to the embodiments described here without departing from what is covered by the claims.
At the beginning and end of moving a rig, the rig rests on the ground as shown in
Once the rig structure 10 has been raised off the ground, skid tracks 14 are slid underneath those portions of the rig structure which would contact the ground surface 19 when lowered. The ground surface 19 may be any surface on which the rig rests including a manufactured or prepared surface such as conventional rig matting. The skid tracks 14 include a sliding layer 18 of continuous or sectioned low friction plastic sheet (see
As shown in
In an embodiment, the sliding layer 18 may be ½ inch thick. The sliding layer 18 may be the same width as or narrower than the base 20. The cooperating layer 22 may be as wide as the ground contacting parts of the rig structure. The layer 22 may be narrower than the layer 18. The layer 18 may be provided in sections 24 inches wide. The layer 18 may be screwed onto the base 20. A dry film coefficient of friction of 0.08 between the layers 18 and 22 has been found adequate, for example, as occurs between TIVAR® DrySlide UHMW-PE used as the sliding layer 18 and stainless steel used as the cooperating layer 22 but other levels of friction may be adequate depending on the towing ability of a vehicle used to pull the rig structure and the integrity of the rig structure 10 at the tow points. With the skid tracks 14 in position, the rig structure 10 may then be lowered onto the skid tracks 14 with the rig structure 10 contacting the cooperating layer 22 when present or the sliding layer 18 (see
Once the weight of the rig structure 10 is off of the jacks 12, the beams 16 and jacks 12 may be removed (as shown in
When towed, the rig structure slides on the sliding layer 18, usually with the sliding interface being between the plastic sheet forming the sliding layer 18 and the cooperating layer 22 formed of stainless steel. The plastic sheet such as sheets of UHMW-PE are self-lubricating, thereby significantly reducing the sliding friction despite the substantial weight of the rig structure. In an embodiment, the cooperating layer 22 moves in relation to the sliding layer 18, while the rig structure remains stationary with respect to the cooperating layer 22. In this instance, the important coefficient of friction for sliding purposes is the coefficient of friction between the sliding layer 18 and the cooperating layer 22. Depending on the rig structure base, the cooperating layer 22 could be omitted in some circumstances, but it is recommended to use a cooperating layer 22 in most instances. Instead of a metal cooperating layer 22, other smooth and strong cooperating layers may be used.
Once the rig structure 10 has arrived at the desired location, the rig structure 10 may be raised again upon the jacks 12 as shown in
In an experimental design, a base layer 20 was made of high density hardwood (oak) plywood painted to reduce moisture and oil absorption was too brittle and would fracture when a raise pad was encountered. Therefore, it was found that a fracture resistant base layer 20 was needed, for example, ¾ inch cabinet grade fir plywood was found to have the required flexibility and strength. Other materials could also be used in place of the fir plywood having substantially the same or better fracture resistance. In the experimental design, a sliding layer 18 made of Jaytrex Virgin Natural White UHMW did not work well in higher temperatures (+25 C). It seemed to get a little “sticky.” The Dry Slide UHMW by Quadrant Plastics was firmer at higher temperatures exhibiting less friction. Therefore, it is preferred to use a sliding layer 18 that is temperature resistant, namely that retains its sliding properties above 25 C, for example, up to 40 C. For the cooperating layer, it has been found that lighter stainless steel (18 gauge) did not disperse the weight at the edges of the load, reducing the effective surface area between the cooperating layer 22 and sliding layer 18. 16 gauge stainless steel has alleviated this issue. Therefore, it is preferred to use a cooperating layer 22 that is sufficiently flexible to be slid under the lifted drilling structure when it is lifted a very short distance, yet being bending resistant under the load of the drilling structure to disperse the weight of the drilling structure at the edges of the load and maximize the effective surface are of contact between the cooperating layer 22 and sliding layer 18.
In the claims, the word “comprising” is used in its inclusive sense and does not exclude other elements being present. The indefinite articles “a” and “an” before a claim feature do not exclude more than one of the feature being present. Each one of the individual features described here may be used in one or more embodiments and is not, by virtue only of being described here, to be construed as essential to all embodiments as defined by the claims.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2869252 | Oct 2014 | CA | national |
