BOP coiled tubing

Plugging and Well Abandonment: Coiled Tubing

Coiled Tubing (CT) has emerged as a powerhouse in well interventions and decommissioning activities over the last two decades, witnessing a remarkable surge in global deployment.

According to the Intervention and Coiled Tubing Association (ICoTA), the CT rig count skyrocketed in 2015 when it came to availability for interventions. Surprisingly, despite the oil price slump since 2015, the CT fleet has only seen a modest 8% reduction, underscoring its resilience.

Now, with oil prices reminiscent of market levels in 2004-05, the CT fleet has expanded by a staggering 68%. The question on everyone’s mind is, where is the fleet size headed? This surge is not just a product of favorable oil prices; it is intertwined with the industry’s strategic response to economic shifts and regulatory dynamics.

In this landscape of fluctuating oil prices and evolving industry trends, the demand for well interventions and Plug and Abandonment (P&A) operations is on the rise. Plug and Abandonment (P&A) is the critical phase in the life cycle of oil and gas wells that ensures the safe and environmentally responsible closure of wells that are no longer in use.

Operators, faced with the challenge of adapting their cost structures for profitability, are turning to CT interventions for their proven efficiency and cost-effectiveness. This shift is not merely a trend but a global movement, with coiled tubing interventions gaining momentum worldwide.

The versatile and efficient tool has gained prominence in P&A operations due to its flexibility, reach, and cost-effectiveness. CNPS experts explore the various aspects of using coiled tubing for plugging and well abandonment, covering the processes, challenges, best practices, and technological advancements associated with this crucial operation.

Coiled Tubing Technology: An Overview

Coiled tubing is a continuous, flexible pipe wound on a large reel. It comes in various diameters and lengths. The tubing can be spooled onto a reel, transported to the wellsite, and injected into the wellbore without the need for the traditional jointed pipe. The continuous nature of coiled tubing allows for various operations, including fluid pumping, wellbore cleanout, and deployment of downhole tools.

Key Advantages Of Coiled Tubing In Plugging And Well Abandonment Operations

Flexibility and Reach

Coiled tubing’s inherent flexibility allows it to navigate through complex wellbore geometries, including horizontal, deviated, and highly tortuous well paths.

Its continuous nature enables reaching substantial depths within the wellbore, providing access to various zones for effective abandonment.

Continuous Operations

Coiled tubing operations are continuous, eliminating the need for tripping in and out of the well for jointed pipe. This results in time savings, increased efficiency, and reduced operational costs during the P&A phase.

Reduced Environmental Footprint

Coiled tubing operations generally require smaller equipment and have a reduced environmental footprint compared to traditional jointed pipe operations. This is especially crucial in environmentally sensitive areas.


Efficient Wellbore Cleanout

Coiled tubing is often employed for wellbore cleanout before P&A activities. Its continuous pumping capabilities effectively remove debris, scale, and residual fluids from the well, creating a clean and well-prepared environment for abandonment.

Precise Cement Plug Placement

Coiled tubing can be equipped with tools for precise perforating and cement plug placement. This ensures accurate placement of cement barriers at strategic locations within the wellbore, contributing to effective zonal isolation.

Adaptability to Zonal Isolation Needs

Coiled tubing’s adaptability is particularly beneficial in mature fields with existing infrastructure, where wells may have unconventional trajectories and zonal isolation needs can vary. It can efficiently address the complexities associated with different well conditions.

Real-time Monitoring and Control

Coiled tubing operations can be monitored in real-time, allowing operators to assess downhole conditions, verify the effectiveness of cement placement, and make adjustments promptly to address unexpected challenges.

Cost-Effective Cementing Solutions

Coiled tubing provides a cost-effective solution for cementing operations in P&A. Its continuous pumping capabilities and adaptability contribute to efficient cement placement, reducing overall costs associated with abandonment.

Enhanced Safety

The use of coiled tubing reduces the number of manual interventions in the wellbore, minimizing risks associated with traditional jointed pipe operations. This enhances overall safety for personnel involved in P&A activities.

Access to Challenging Environments

Coiled tubing can access challenging environments, including deep-sea wells and unconventional reservoirs, where traditional methods may be less practical. Its flexibility and adaptability make it suitable for a wide range of operational settings.

Improved Efficiency in Horizontal Wells

In horizontal wells, where achieving uniform cement coverage can be challenging, coiled tubing’s flexibility allows for effective cement placement, ensuring zonal isolation in these unconventional wellbore trajectories.

Advanced Downhole Tool Integration

Coiled tubing can be integrated with advanced downhole tools, such as logging instruments and cutting tools, enhancing its capabilities in P&A operations and ensuring efficient and reliable abandonment processes.

Reduced Rig Time

The continuous operations and efficiency of coiled tubing contribute to reduced rig time during P&A campaigns. This leads to cost savings and a more streamlined abandonment process.

Minimization of Environmental Risks

By efficiently isolating and sealing abandoned wells, coiled tubing helps minimize the environmental risks associated with fluid migration, methane emissions, and potential wellhead hazards.

P&A Processes Using Coiled Tubing

Cement Plug Placement

Primary Cement Plug: The primary objective of P&A is to isolate the hydrocarbon-bearing zones from the surface and other non-productive zones. Coiled tubing is used to place cement plugs at strategic locations within the wellbore. The first cement plug is typically set in the production or injection zone to isolate it from the wellhead.

Intermediate Cement Plugs: Additional cement plugs are placed at intermediate depths to isolate different zones within the well further. These intermediate plugs contribute to the overall zonal isolation, preventing fluid migration and ensuring compliance with regulatory requirements.

Surface Plug: The final cement plug, known as the surface plug, is placed near the wellhead to permanently seal the wellbore. This plug serves as the last barrier, ensuring that no fluids can migrate between the well and the surface.

Perforating and Cutting Operations

Perforating for Plug Setting: Coiled tubing can be equipped with perforating guns to create holes in the casing at specific depths. These perforations allow for the placement of cement plugs precisely where they are needed, contributing to effective zonal isolation.

Cutting Casing for Section Removal: In some P&A scenarios, it may be necessary to remove certain sections of the casing before setting cement plugs. Coiled tubing can be fitted with cutting tools to remove casing sections efficiently, providing access to the wellbore for further operations.

Logging and Evaluation

Coiled tubing can be utilized for logging and evaluation operations during the P&A process. Logging tools can assess wellbore conditions, verify cement placement, and ensure the effectiveness of the cement barriers. Real-time data from logging tools enables operators to make informed decisions and confirm that the P&A objectives are being achieved.

mudlogging unit by CNPS

Challenges in Coiled Tubing P&A

Wellbore Complexity

Mature fields often have complex wellbore geometries with multiple deviations, intersections, and irregularities. Coiled tubing must navigate through these complexities to reach the targeted depths for cement plug placement. Proper planning, surveying, and real-time monitoring are essential to overcome these challenges.

Zonal Isolation

Achieving effective zonal isolation is paramount in P&A operations. Incomplete zonal isolation may result in the migration of fluids between different formations, posing environmental and safety risks. Coiled tubing must be deployed strategically to ensure that cement plugs are accurately placed, providing robust zonal isolation throughout the wellbore.

Verification of Cement Integrity

Ensuring the integrity of cement barriers is crucial for the long-term success of P&A operations. Coiled tubing facilitates the deployment of logging tools to verify the placement and quality of cement plugs. However, challenges such as cement channeling, poor bonding, or incomplete curing can still occur and require careful assessment and remediation.

Regulatory Compliance

Meeting stringent regulatory requirements for P&A operations is an ongoing challenge. Regulatory standards vary across regions, and operators must stay abreast of changes and ensure that their coiled tubing P&A procedures align with the latest environmental and safety regulations.

Best Practices in Coiled Tubing

Comprehensive Wellbore Survey

Before initiating P&A operations, conducting a comprehensive wellbore survey is essential. This survey should include detailed information about the well’s trajectory, deviations, casing specifications, and any existing downhole equipment. This information guides the planning and execution of coiled tubing operations, ensuring that the equipment is suited to the specific wellbore conditions.

Real-time Monitoring and Control

Utilizing real-time monitoring systems during coiled tubing operations enhances control and decision-making. Continuous monitoring allows operators to assess downhole conditions, verify the effectiveness of cement placement, and make adjustments to address any unexpected challenges in real-time.

Quality Assurance for Cementing

Implementing rigorous quality assurance measures for cementing operations is critical. This includes pre-job testing of cement slurry properties, ensuring proper mixing procedures, and conducting post-job evaluations to verify the integrity of the cement barriers.

At CNPS, we understand that quality assurance protocols contribute to the reliability and safety of operations across the oil and gas sector. We offer everything from mud logging sensors to GRE screen tubes, casing, storage tanks, and RTP & FRP products to help your oil and gas company progress like you envisioned.

Request a quote for our oil and gas services and equipment, renewable energy solutions, and electronic products. Contact us at or +86 183 546 39099 to learn more.

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