Setting up for Success: Disposable Setting Tools

I’ve had two previous articles about the two primary redressable setting tool designs used to set composite frac plugs during a plug and perf operation. These tools are known as the Baker E4 and the Owen Compact and the articles are here and here, respectively. Over the last year, another competitor has started to capture a major portion of the market. The new entrant is the disposable setting tool, originally patented and supplied by Diamondback Industries. The intent of the design was the simplify the tool and lower the cost enough to be provided as a one time, or disposable, setting mechanism. The main downfall of the original setting tools is the redress procedure, and providing a disposable tool ensures it is built in a factory environment and never relies on-field personnel to ensure the success of the tool.

Design

Ultimately the setting tool converts explosive energy to mechanical energy by providing an explosive charge that creates pressure that acts 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 likely leftover from the original purpose of the tool to set long complex production packers. 

The Baker E4-20 has 34 parts, including the bleeder port and 17 o-rings, which leads to the complexity and difficulty associated with 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. Based on publicly available information, it has 8 parts including 4 o-rings and a shear screw.

When either of these tools is retrieved from the well it still has pressure captured that must be bled off on surface using the bleeder port. This requires care and can cause harm to the operator if it isn’t done properly. The disposable design bleeds while in the well, eliminating this potentially dangerous operation.

Surface Operation

The setting tool operation for the service supplier is different between the traditional setting tool and disposable. For the traditional tools, the operator is required to ensure the tools are built properly, run the tool, bleed the pressure, tear the tool down on location, redress the tool by replacing all seals and oil, rebuild the tool, install the power charge equipment, and run the tool again. For a zipper operation, this could be required to be done up to 15 times a day. To achieve this the operator must have at least an additional person on location for this portion of the operation.

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. Much easier!

Downhole Operation

From an operational standpoint, there are two main parts of the disposable setting tool. The mandrel and the cylinder. The mandrel contains the burn chamber as well as the static connection to the frac plug. The cylinder creates the piston area, between the mandrel and the cylinder, as well as strokes to set the plug. During the operation of the tool, the power charge burns in the power chamber which generates a 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.

Summary

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.