The first step in the plug and perf process is to connect the plug to the setting tool. Each plug design is unique, and the connection to the setting tool is no different. The plug connection requires a kit of metal parts called the Wireline Adapter Kit (WLAK). The wireline setting tool creates a mechanical force when an explosive power charge in the tool creates pressure. The pressure acts on a piston that applies a force to set the plug.
One of the most significant variables in the plug & perf operation is the performance of the setting tool. Understanding how the tools operate and possible risks provide greater insight into any issues during setup and setting.
There are three setting tools Baker Type, Owen Type, and Disposable. Baker and Owen tools are redressed and reused, while the disposable tools are, well, disposed of. All work on the same concept but perform them in slightly different ways. They contain the following parts: Firing Head, Power Charge, and Piston. A wireline signal is sent to the firing head when ready to set the plug, igniting the power charge. As the power charge burns, creating pressure in the tool. The pressure acts against the piston, which applies a force into the composite plug setting it in place.
The Baker setting tool design is the E-4 Wireline Pressure Setting Assembly. There are two main sizes used for Plug & Perf operations the Baker E4 #10 and E4 #20. Composite plugs designed for 5″ casing and below use the #10, and 5.5″ and above use the #20. Each tool provides a certain amount of stroke and force:
When designing a composite plug, these are the constraints engineers work within to develop the tool. If the force required to set the tool is too high or the stroke too long, the setting tool will not separate from the plug after setting.
Setting Tool Operation
The operation for the Baker E4 Setting tool is as follows:
- 1. The Firing Head ignites the power charge.
- 2. The Power Charge burns, creating pressure in the gas chamber.
- 3. The pressure acts against the Floating Piston.
- 4. The Floating Piston then transfers this force to the oil below the piston in the Upper Cylinder, Cylinder Connector, and Lower Cylinder.
- 5. The oil then transfers the force to the piston in the Lower Cylinder.
- 6. This Piston is connected to the Piston Rod and Crosslink.
- 7. The Crosslink passes through the Setting Mandrel and connects to the Crosslink Sleeve.
- 8. The Crosslink Sleeve then moves downward, transmitting the force to the composite plug and setting the assembly.
Setting Tool Redress Is Critical
During a Plug & Perf operation, each plug set relies on the setting tool to work as designed. After each run, the setting tool is removed from the well, redressed, and run again. This redress step introduces risk into the operation. Each E4 setting tool has seven sets of seals that protect the tool’s inner workings from the well environment. Also, it contains a chamber that must have the correct amount of oil depending on the temperature in the well. The redress of the tool, including replacing the seals and adequately filling the oil chamber, is critical to the setting tool performance and the entire operation.
If the seals in the gas chamber fail, the fluid in the well will flood the tool rendering the power charge inoperable. Also, as the wireline BHA lowers into the well, the hydrostatic pressure will act against the floating piston causing the tool to prematurely stroke, which is one of the most significant causes of a plug preset.
If the seals in the oil chamber fail, the well hydrostatic will work against the piston and piston rod to pre-stroke the tool. Leaks in the lower section of the tool, around the piston rod, will allow the hydrostatic to work against the setting force, causing a soft set or keeping the tool from fully stroking. Properly replacing and installing the seals should be a major focus of the company redressing the setting tools.
Correctly filling the oil chamber can affect the tool as well. If there is too much oil, the temperature in the well will cause it to expand, applying force on the piston and prematurely stroking the tool. Too little oil could limit the required stroke, keeping the tool from fully setting the composite plug. The procedure for redressing the Baker E4 setting tool is on the Baker Hughes website:
The setting tool is often forgotten during the planning for Plug & Perf but plays a significant role in the success of the completion operation.
WellBoss Service Technicians
Ensuring that your service companies understand this and are skilled at redressing the tools will increase the performance of your completion. WellBoss has trained service technicians that will ensure your plugs run flawlessly. While on location, they capture over 30 pieces of data during the operation to reduce risk and increase the reliability of the job. We can even provide the setting tool service on location, allowing the wireline company to focus on the quality of the guns and deployment.