Perf gun malfunctions during operations can significantly impact the timing and cost of your completion. The WellBoss Frac Shuttle Technology is the best technology for mitigating these issues.

For over a decade, oil and gas operators have worked to increase the speed and efficiency of their completion operations. Every part of the process is studied, innovated, and optimized to drive risk out of the operation to increase the ROI of their asset. The dominant completion methodology in North America is known as Plug & Perf.

Plug & Perf

The Plug & Perf process involves running a wireline BHA consisting of a plug, plug setting tool, and a series of perf guns. When the BHA reaches the bottom of the current zone, the setting tool will set the plug in the casing, releasing it from the BHA. The operator then pulls the guns upward, fires at a planned depth, and repeats until each gun has fired and the stage is fully perforated. After wireline removal, the stage is frac’d. The process repeats to treat the entire well.

Perf Gun Switches

The perf guns are activated via an electric signal through the wireline down to a switch at each gun. Historically, the switches were pressure activated sequentially for each stage. In the following process:

  • The first switch is armed and ready to fire when the signal is received
  • Upon firing the first gun, the pressure from the blast arms the second switch.
  • The process repeats until all guns in the string fire.

The challenge with these switches is that a malfunction affects the ability to fire the rest of the gun string. If the first switch fails, the whole gun string is lost.

The most common switch used today is addressable. Each switch is controlled separately and does not rely on another switch’s performance. If one switch fails, the rest of the gun string remains functional. These have significantly reduced the number of gun-related issues during the completion process. Though, connection to the guns can cause the entire string to malfunction.

Plug Configuration

The first step in the Plug & Perf process involves pumping the wireline BHA down to its location in the well’s horizontal section. Pumping the BHA down requires the fluid to have a flow path into the reservoir. Operators will choose two plug configurations during the frac: Ball-Drop or Ball-In-Place.

By definition, a Frac Plug has a hollow mandrel. There is a flow path through the plug. Landing a ball on the mandrel to seal this flow path provides isolation from the zone below. With a ball drop configuration, the plug is run without a ball, following this process:

  • Set Plug
  • Perforate Stage
  • Remove Wireline
  • Drop Ball
  • Frac

Eventually, the ball lands on the plug to isolate the zone.

For ball-in-place, the ball runs with the plug, eliminating the time and fluid required to pump the ball down before the frac.

Pros & Cons

The primary benefit of Ball-In-Place is the frac operation’s increased time/water efficiency. Immediately after removing the wireline, the frac treatment can begin. A smaller benefit is the ability to pressure test the plug after setting; this assures the operator that the plug will perform during the frac.

This configuration creates a challenge if the guns do not fire. Without the perforations, there isn’t a flow path to pump the next set of guns down once the issue is corrected. In this situation, the operator will try to produce the ball to the surface to remove the isolation from the zone below. If this cannot be achieved, they have call out coiled tubing or a wireline tractor to get the repaired guns down to perforate the stage. This interruption can have a significant impact on the frac operation.

Gun Misfire Technology

Several plug suppliers have developed solutions to provide the efficiency of ball-drop and the flexibility of ball-in-place.

Ball Catch

One method is to include a ball catch mechanism in the setting kit connected to the setting tool:

  • Set and Release from the plug
  • Guns do not fire
  • Use well pressure/flow to flow the ball back into the setting kit
  • The catch mechanism traps the ball in the BHA
  • The ball returns to the surface with a wireline

This simple solution relies on a certain amount of flow from the zone below to activate the ball catch. In some low-pressure situations, it may be ineffective.

Pinned Ball

Another way to tackle this problem is to pin the “ball” (the “ball” may have a different shape than a sphere) in the mandrel of the plug with flow ports below. After setting, if the guns do not fire, you can pump fresh guns down through the ports and into the formation below. When frac ramps up flow, pressure builds up on the “ball”, shearing the pins and allowing it to land on a seat to isolate the zone. There are three challenges with this solution.

First, with the ball pinned above the seat, you cannot pressure test the plug after setting.

Second, operators aim for 18-22 bbls/min of flow rate to pump guns down, requiring high flow rates through the ports without shearing the pins holding the ball. When most fracs have 150’+ of perforated zone treated at 100 bbls/min, it is unclear if you ever get the 22 bbls/min through the plug to shear the pins.

Finally, if the “ball” comes out of the mandrel it is unlikely to go back in to recreate isolation. This would require the running of another plug to achieve isolation.

The Best of Both Worlds

WellBoss has developed and deployed a patent-pending solution that has proven to provide all the benefits today’s operators require. The Frac Shuttle Technology enables the efficiency of ball-in-place with the flexibility of ball drop.

The frac shuttle runs with the plug like a ball-in-place ball would. During a normal frac stage, the plug would operate exactly as a ball-in-place configuration.

  • Set the Plug
  • Immediately Pressure Test
  • Pull up Wireline BHA
  • Perforate, Frac, Repeat

In the event of a gun misfire, follow this procedure:

  • Set the plug
  • Immediately pressure test
  • Realize there is a gun misfire
  • Pull the wireline from well
  • Pressure up to activate the shuttle
  • Bleed off to shut in pressure
  • Start pumping to verify a flow path
  • Pump the next set of guns down up to 22 bbls/min
  • Perforate
  • Drop ball
  • Frac

The frac shuttle allows you to pressure-test the plug immediately after setting to verify you have isolation and does NOT require high flow rates from below to create a flow path when needed.

Also, you do not have to run another plug after activating the shuttle. A ball can be dropped from surface to re-establish isolation.

The Frac Shuttle and the Boss Hog All Composite provide a gun misfire mitigation feature with the market’s most reliable composite frac plug.

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