Introduction
There are many different types of tubular cutters available in the oil & gas industry. Applications are commonly to sever drill pipe, coil tubing, or retrieve the completion string from the well by cutting a tubular joint or at the cut to release packer assembly.
As with all deployments into the well, it is important to plan and choose the correct cutter for each application along with its deployment method. Ideally, all cutting operations are preferred to be conducted with the drill pipe or completion string in tension, usually string weight plus 10%, where possible. Damage to the casing, or behind tubing, may occur if the wrong cutter is chosen. Some cutters are not able to cut in a gas environment, so fluid level and type may become a factor to consider. If an explosives cutter is to be run with wireline tractor conveyance, then there may be a high risk that the tractor may part or fail on cutter activation. All cutting tools should be used within their specified temperature and pressure limits.
Types of Cuter on the Market
Cutting options can broadly be placed into the following categories:
· Explosives Cutters
· Electromechanical Cutters
· Chemical Cutters
· Radial Cutting Torch
Explosive cutters:
Explosives cutters can be broken down further into the following applications.
Drill Collar Severing Colliding Tool: These are used to sever pipe in recovery operations, utilising precisely timed explosive charges to cut through drill collars and other heavy-duty materials. The cutting attempt should be made above the struck point. Significant pipe damage and splitting will occur during the process.
Shaped Charge Cutters: These employ explosive charges to focus a blast into a metal jet that penetrates and cuts the target material. They are used for precise severance in downhole operations. Flaring of the tubular is expected during the cutting process but has been improved to minimise this effect. Some cutters are designed to split the collar and release the tubular in this manner. Consideration is needed when designing a completion to ensure the cutter can be accurately positioned for a cut to release packer. A landing nipple above the packer can assist in this process.
Note: While explosives cutters are common in the oilfield they may be difficult to transport to the wellsite on short notice due to the individual country security restrictions. Explosive cutters can cut with the string in tension or compression.
Chemical and Radial Cutting Torch:
Chemical Cutters: These utilise chemicals like bromine trifluoride to dissolve metals cleanly without debris. They are particularly useful in sensitive or difficult-to-access environments, however there are significant safety precautions that are needed to be able to deploy this equipment due to extremely harmful chemicals and their bi-products.
Radial Cutting Torch (RCT): Utilizes a plasma jet to cut through materials. This tool is non-explosive and can be deployed rapidly worldwide due to fewer transport restrictions, although there may be some exceptions to this.
Due to their cutting action there is no flaring of the tubular. These type of tool are typically the only option to cut coil tubing.
Note: Due to the nature of these tools it is important to have them centralized correctly. Both of these tools can be susceptible to becoming stuck to the tubing wall during the cutting process. Ideally activated with the string in tension plus 10%.
Electromechanical Cutters:
Electromechanical Cutters: These cutters use rotating or reciprocating cutting heads or blades that are powered electrically and monitored from surface during the cut process. These types of tools are ideal for environments where explosives or chemicals pose a risk, or where it’s logistically not possible to transport them to the wellsite. While many tool suppliers state that their tools can cut in both tension and compression, a string in tension would always be optimal. Where the string is in compression, consideration is needed to avoid issues with bladed tools becoming stuck on tubular break through, or when a tool stalls during a cut that is unable to restart due to limitations in their design. Tool retrieval can become challenging when an electrical short circuit occurs during the cutting process. As with many cutters, accurate centralisation is essential for success.
Note: One major advantages of electromechanical cutters over other cutting methods is the potential to complete multiple cuts during one decent into the well.
Additional tool Information and their suppliers can be found in the table below.
New Technology
The aforementioned cutting tools have been around for many years and are well established methods of cutting pipe. However there is a new cutting tool that is being introduced into the market.
Arkane Technology has developed an autonomous battery powered electromechanical pipe and tubing cutter that leaves a CNC finish. The tool can cut with the string in compression, or in tension, due to the V-shaped cutting method, using a patented 3-Axis cutting technique, (Downhole Autonomous Reciprocating Cutter).
Applications
Drill Pipe and Heavyweight Cutting for Pipe Recovery
Tubing Cutting for Intervention and Abandonment
Packer Cut to Release Cutting
Internal Profile Milling
Features
Memory Mode for Slickline Conveyance
Surface Initiation Mode (with Feedback) for E-line and Digital Slickline Conveyance
Alkaline Battery Pack
Patented 3-Axis Cutting Technique
Built in Safety Features for Retrieval Assurance
Cuts: from 2 ⅞” to 5 ½” in Chrome & Exotic Materials
Benefits
No Explosives or Dangerous Goods
No Additional Surface Equipment Required
CNC Quality Finish
Cuts with the string in compression or tension
Technical Advisory
Cutting operations, especially in complex industrial environments such as oil and gas extraction, face several challenges. Understanding these challenges helps in planning and optimizing the use of cutter tools for various applications.
Considerations for Planning Cutter Tool Usage
When planning to use a cutter tool, customers should consider several key factors to ensure the selection of the appropriate tool and method:
1. Understand the Material Properties: Knowing the hardness, toughness, and other material characteristics can help in selecting the right cutter type, whether mechanical, explosive, or chemical.
2. Evaluate the Operating Environment: Consider the temperature, pressure, fluid properties and potential chemical exposure in the environment where the cutting will occur. This helps in choosing tools that are designed to operate under these specific conditions.
3. Safety and Regulatory Compliance: Choose cutting methods that align with safety standards and regulatory requirements, especially in sensitive environments. Non-explosive and non-chemical methods are increasingly preferred for their lower risk profiles.
5. Prioritize Precision and Cleanliness: For operations requiring high precision, select cutting tools that maintain the integrity of the cut surface and minimize debris
6. Consider Operational Efficiency: Tools that can cut quickly and reliably without frequent maintenance or downtime will reduce operational costs and increase efficiency. Some mechanical cutter can perform multiple cuts in one decent.
7. Consider positive positioning accessories for the cutter, where depth accuracy is critical in cases such as cut to release packer window.
8. Post-Cut Processing: Think about what happens after the cut. If the tool leaves the workpiece in a condition that requires significant post-process work (like milling or additional machining), it may not be the most cost-effective choice.
9. Understand the limitations of different types of cutters and assess the remedial actions to be taken where a tool fails to achieve its intended objectives.
By considering these factors, customers can select the most appropriate cutting tool for their specific needs, ensuring safety, efficiency, and effectiveness in their operations.
Conclusion
There are many pitfalls with running cutters, whatever their type. As with other operations the proper planning and selection of suitable equipment is critical to its success. Equipment preparation has to be meticulous and deployment completed using experiences crews. Understanding the failure mode of any given tool allows an operator to assess the risks and put contingency plans in place, so that recovery of the equipment from the well can be made.
If you have any upcoming operations and are unsure of what cutting option is best suited to your needs, then please get in touch with one&zero , where our team of experts will be happy to discuss your requirements.
