Patent Application
20110315403
The present invention relates generally to setting frac plugs in oil and gas wells.
Frac and bridge plugs are used to isolate zones in a well. Plugs typically are placed in position using a setting tool, such as a hydraulic setting tool. The frac plug is attached to the setting tool which is then run downhole on coiled tubing, jointed pipe or other conduit. It is not unusual to encounter debris as the plug is advanced down the well. This debris tends to collect ahead of the bottom hole assembly (“BHA”) and may slow or even block proper positioning of the plug.
Some frac plugs have a flow passage that allows fluid to pass up through the plug from the well below after the plug is set. The present invention takes advantage of this flow passage by employing a hydraulic setting tool with a flow passage to provide fluid communication through the entire BHA as the plug is being advanced. Thus, fluid can be circulated through the well to wash away debris as the plug is advanced to the selected location in the well.
Setting tools are used to set a variety of plugs and packing devices. One difficulty associated with setting such devices is determining when and if the plug or device has been completely and successfully deployed. The setting tool of the present invention incorporates a fluid bypass system that reliably indicates successful deployment of the plug or other device by producing a precipitous drop in the hydraulic pressure. This is accomplished by using a system of fluid bypass ports that become aligned only when the sliding component of the setting tool has traveled a distance sufficient to completely set the plug.
Turning now to the drawings in general and to
The BHA 10 shown in
The adapter 32 and frac plug 34 are shown in more detail in
The adapter 32 comprises an inner tension mandrel 50 and an outer sleeve 52. The uphole end 54 of the sleeve 52 is threaded for connection to the setting tool 30, as will be described in more detail hereafter. The tension mandrel 50 is tubular with a wider lower portion 56 and a narrower upper portion 58. The upper portion 58 has a threaded end 60 for connection to the setting tool 30 as described further below. The lower portion 56 is sized to slidingly receive the upper end 62 of the plug mandrel 42 and is connected thereto by at least one and preferably a plurality of shear pins or screws, designated collectively at 64. By way of example only, the shear screws 64 may comprise 5 shear screws, each having a maximum shear strength of 5000 pounds so that 30,000 pounds of force is required to break them and release the frac plug. The inner bore or lumen 66 of the tension mandrel 50 forms a flow passage therethrough continuous with the flow passage 48 in the plug 34.
It should be noted that an adapter is not essential to the present invention. Rather, in some instances a setting tool may be designed to be connected directly to the frac plug (or other device). That is, the components required to connect the setting tool to the frac plug may be incorporated in the setting tool. However, as is well known in the art, the use of an adaptor permits a particular setting tool to be used with multiple sizes and types or plugs.
The preferred setting tool 30 connected to the adapter assembly 32 is shown in
The upper housing assembly 70 preferably comprises a top sub 76 with an uphole end 78 threadedly connectable to the well conduit (not shown) or to another BHA component, such as the oriented perforating tool 22 (
In the preferred embodiment, the mandrel assembly 72 comprises a plurality of tubular components all axially fixed relative to the upper housing assembly 70. An elongated tubular piston mandrel 90 is connected at is uphole end 92 to the downhole end 84 of the top sub 76. The piston mandrel 90 is threadedly connected at its downhole end 94 to the uphole end 96 of a circulating sub 98 (
As best seen in
Referring still to
As best shown in
A plurality of ports 150 are formed in the bypass sleeve 142. Ports 152 are also formed in the circulation sub 98. Ports 154 are formed in the push sleeve 130. The ports 150, 152, and 154 are sized and positioned to be alignable with each other when the slide assembly 74 is moved axially a selected distance “D” (
The above-described components of the setting tool 30 are configured to provide a hydraulic system 160 for driving axial movement of the slide assembly 74. The preferred configuration for the hydraulic system 160 includes an upper fluid chamber 170, which contains the head 122 of the upper piston 120, and a lower fluid chamber 172, which contains the lower piston 136. The piston mandrel 90 includes an annular flange 174 along its length to form a divider between the upper and lower chambers 170 and 172. As seen in
The upper chamber 170 (
The lower chamber 172 is defined by the inner diameter of the upper piston body 126 and the outer diameter of the piston mandrel 90 below the annular flange 174. Ports 186 (
Having described the structure of the preferred BHA 10, its operation now will be described with continued reference to
Once the plug 34 is positioned at the correct level, a ball 118 (
Once the shear pins 134 have broken, the slide assembly 74 moves downward in response to the force on the piston head 122 and the lower piston 136. After several inches of travel, the frac plug 34 will be fully deployed. In most instances, 4-5 inches of travel will be sufficient to set the plug 34.
The slide assembly 74 continues to move downwardly until the lower piston 136 engages the upper end of the bypass sleeve 142. The force on the sleeve 142 increases until sufficient to break the shear pins 144, whereupon the slide assembly 74 completes its full travel distance “D” (
The aligned ports 150, 152, and 154 allow a sudden increase in the flow of fluid out of the tool, causing a dramatic drop in the pressure reading at the wellhead (not shown). As used herein, “rapid and substantial pressure drop” refers to a pressure drop that is sudden and large enough to be readily perceived by the well operator and sufficient to signal to the operator that the setting operation is completed. By way of example only, in the preferred setting tool, alignment of the ports should produce at least about a 2000 psi pressure drop in a bout fifteen seconds.
Having successfully deployed the frac plug 34, the frac plug is disengaged from the BHA. Continued pressure from the hydraulic system breaks the shear pins 64 between the tension mandrel 50 in the adapter 32 and the plug mandrel 42, releasing the connection between the BHA and the plug 34. Thereafter, the BHA may be withdrawn from the well.
For the purpose of this description, the words left, right, front, rear, top, upper, lower, inward, outward, uphole, downhole, bottom, up, upwardly, down, downwardly, inside, and outside may be used to describe the various parts and relative positions of structures and operations in the present invention as depicted in the drawings. These descriptive terms should not be considered as limiting the possible orientations of the invention or how it may be used.
Now it will be appreciated that the present invention provides frac plug setting tools and methods that offer many advantages. The bottom hole assembly provides a “flow through” function that allows fluid to be circulated through the well ahead of the frac plug as it is being advanced toward the desired location. The setting tool includes a bypass feature that is mechanically simple and reliably signals the successful deployment of the plug. As regards the setting tool, it should be noted that a setting tool with this bypass function is useful in operations other than setting frac plugs and with or without the “flow through” feature.
The embodiments shown and described above are exemplary. Many details are often found in the art and, therefore, many such details are neither shown nor described herein. It is not claimed that all of the details, parts, elements, or steps described and shown were invented herein. Even though numerous characteristics and advantages of the present inventions have been described in the drawings and accompanying text, the description is illustrative only. Changes may be made in the details, especially in matters of shape, size, and arrangement of the parts within the principles of the inventions to the full extent indicated by the broad meaning of the terms of the attached claims. The description and drawings of the specific embodiments herein do not point out what an infringement of this patent would be, but rather provide an example of how to use and make the invention. Likewise, the abstract is neither intended to define the invention, which is measured by the claims, nor is it intended to be limiting as to the scope of the invention in any way. Rather, the limits of the invention and the bounds of the patent protection are measured by and defined in the following claims.
