Redress of setting tools and their proper deployment have become a thorn in the side of operators looking for smooth and efficient operations during their frac. One solution to this problem is disposable setting tools. Providers of the tools have simplified the setting tool design to lower the cost enough to be provided as a one-time, or disposable, setting mechanism. Providing a disposable tool ensures it is built in a factory environment and never relies on-field personnel to ensure the tool’s success.
Ultimately the setting tool converts explosive energy to mechanical energy by providing an explosive charge that creates pressure on a piston. Once applied, the piston shifts downward, setting the plug into the casing. The redressable versions, Baker E4 & Owen Compact, have complex designs that include multiple sections, including oil chambers designed to dampen the force created by the explosive force. The oil chamber is likely leftover from the tool’s original purpose to set long, complex production packers.
The Baker E4-20 has 34 parts, including the bleeder port and 17 O-rings, leading to the complexity and difficulty of redressing the tool on location (sometimes in the middle of the night). The Owen setting tool has 27 parts, including the bleeder port and 13 O-rings. The disposable design works to simplify the design and eliminate the redress on location. It has eight parts based on publicly available information, including 4 O-rings and a shear screw.
After the setting sequence, the redressable tools still have pressure captured that must be bled off on surface using the bleeder port. This requires care and can cause harm to the operator without following the proper procedure. The disposable design bleeds while in the well, eliminating this potentially dangerous operation
The setting tool operation for the service supplier is different between the traditional setting tool and disposable. The procedure for traditional tools include
- run the tool
- bleed pressure
- tear down on location
- redress by replacing all seals and oil
- install the power charge equipment,
- run again.
For a zipper operation, this could be required to be done up to 30 times a day.
The disposable setting tools require the operator to remove the tool from the box, install the power charge equipment, run the tool, and then discard it. Much easier!
From an operational standpoint, the disposable setting tool has two main parts. The mandrel and the cylinder. The mandrel contains the burn chamber and the static connection to the frac plug. The cylinder creates the piston area, between the mandrel and the cylinder, and strokes to set the plug. During operation, the power charge burns in the power chamber which generates gas. The gas expands through the ports in the mandrel and acts on the piston area of the cylinder. A shear screw designed to keep the mandrel and the cylinder aligned and static during run-in will shear as the pressure builds. The cylinder then moves downward applying the setting force to the frac plug. Once the plug is set and the setting tool shears off the plug, the piston will stroke further allowing a hole in the cylinder to pass over the mandrel seal bleeding the pressure from the burn chamber.
The disposable setting tool is more like the Owen Shorty design in that the piston area is created by a piston sliding down a mandrel. The difference is that the Own Shorty design has the piston slide down into an atmospheric chamber. The Disposable Setting tool does not have an atmospheric chamber. This means that tool must overcome the hydrostatic pressure of the well in addition to the force required to set the frac plug. The power charge had to be specifically designed to overcome all the forces exerted on the tool during the setting sequence.
The setting tool provides another risk to the plug & perf operation. In my experience, issues during the redressing of the setting tool is a major cause of issues during plug & perf. The disposable setting tool works to reduce this risk by putting the building of the tool in a controlled factory environment. After some issues experienced with the tool at the beginning of its commercial run, the disposable setting tool seems to be meeting its stated benefits.
With the reduction of risk to aid in the plug & perf operation the disposable setting tool provides I expect it to continue to capture share in the horizontal completions marketplace
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