V0 FLOAT EQUIPMENT: 762 ULTRA MAG VALVE

Citadel recently qualified our new 762 ULTRA MAG valve to 18,000 psi at 400°F with nitrogen gas, using V0 zero bubble acceptance criterion. This testing was performed by Stress Engineering Services in Houston. The gas test was performed after a 20 bpm for 24 hour flow endurance test using 12.9 ppg water based mud at Citadel’s API flow loop at our facility in North Houston.

This groundbreaking performance validation combined with industry leading flow area (7.62 square inches) make the 762 ULTRA MAG the highest performing float valve in the industry by a significant margin.

Contact us or check out the products page to learn more about Citadel float equipment and our other innovative casing equipment/cementing tools.

Another industry first from Citadel: V0 float equipment. If you’re wondering what “V0” is or means, here’s a quick explanation: “V0” is the most stringent product validation grade that comes originally from API 11D1/ISO 14310 (packers and bridge plugs). There are validation grades from V6 (the easiest) down to V0 (the most challenging).

  • V6: supplier/manufacturer defined test criteria
  • V5: liquid test (pressure/temperature only)
  • V4: liquid test plus axial loads
  • V3: liquid test plus axial loads plus temperature cycling
  • V2: gas test plus axial loads
  • V1: gas test plus axial loads plus temperature cycling
  • V0: gas test plus axial loads plus temperature cycling plus zero bubble acceptance criterion

If you’re familiar with API 11D1/ISO 14310 and you’re saying to yourself or to your colleague right now, “those specifications aren’t for float equipment, they’re for packers and bridge plugs”, you’re correct. They are irrelevant to float equipment. However, the term “V0” has evolved in recent years to take on relevance outside of these specifications and the products they govern. The term is now colloquially used to refer specifically to the “zero bubble acceptance criterion” that separates V1 from V0. The V1 validation grade is the same severity of a test as V0, but allows for 20 mL of bypass over each 15 minute hold period, whereas V0 has a zero bubble allowance over the same 15 minute hold period. As such, a leak detection system must be in place in a closed system where any gas bypass through the tested product will be captured and measured. It should be noted that the gas bypasses at high pressure, yet is measured at ambient pressure. In the case of our 18,000 psi pressure test (1225 atm), a gas bubble the size of a water droplet would fill a shot glass when measured at atmospheric pressure.

Typical for float equipment is the API 10F qualification which includes a flow endurance test and an HPHT test each with three levels:

  • I: 10 bpm for 8 hours and maximum pressure of 1,500 psi at ambient temperature
  • II: 10 bpm for 12 hours and maximum pressure of 3,000 psi at ambient temperature
  • III: 10 bpm for 24 hours and maximum pressure of 5,000 psi at ambient temperature
  • A: 1,500 psi at 200°F
  • B: 3,000 psi at 300°F
  • C: 5,000 psi at 400°F

The validation grade for a float valve is designated by the combination of the flow endurance test and the HPHT test (IA, IIA, IIIB, IIIC, etc). There are some issues/limitations to this document which is why it has been updated and re-released as a specification. Specification 10F will be discussed in a future blog post.

So why V0 float equipment? Is that not complete overkill? In most circumstances, yes, absolutely. However, there are circumstances where the float equipment is required to act as a true barrier, preventing fluid flow or pressure from entering the casing when cement is not present or unreliable (intentionally or unintentionally). In a wet shoe system, a barrier style float valve like the ULTRA MAG will prevent formation fluid/gas from entering the casing and making it to surface. Even when a barrier style valve is not required in circumstances such as these, there are benefits to running a bulletproof valve to mitigate NPT and remedial work associated with float failure. A marginal additional expense as insurance to know your floats will hold at the conclusion of the cement job.

Quality is the status quo. Innovation is conventional. Excellence is expected. ORDINARY IS OUR ENEMY.

Speed Versus Accuracy

Carlos Valdez – Technical Professional

Carlos is a mechanical engineer with 5 years of experience in Oil and Gas as a design and sustaining engineer for casing equipment/cementing tools. He graduated from The University of Texas at El Paso with both Bachelor’s and Master’s in Mechanical Engineering. One of his main tasks has been on developing tools to increase production and efficiency at the workplace. Less time spent correcting things gives us more time to developing innovating equipment.

Speed Versus Accuracy

Speed and accuracy are commonly known as a trade-off. The faster you complete a project/task, the more likely you will find that you overlooked some things, resulting in the “If you want it bad, you get it…bad” dilemma.

In a market as competitive as the Oil and Gas industry, having both speed and accuracy can be a determining factor to differentiate among your competition and obtain market share. Thus, the demand of rapid response as well as on time delivery is something that is asked from us every day. It is imperative that we as a company can react quickly and provide the best and most accurate solutions to our customers.

Technology plays a valuable part in this, as it can provide the tools that are necessary to complete this difficult task. The Citadel Casing Solutions mobile app for example, can provide quick answers to our customers by leading them directly to the product’s engineering datasheets. There they can find answers to many of the technical questions they may have instead of having to wait on someone to provide the information for them. Simultaneously, our team is focused on developing tools that can provide our customers with actual drawings and engineering datasheets in a matter of minutes instead of the usual delay of a few days. These automated tools provide accurate and quick results consistently while minimizing human error.

Communication is also key to be able to provide the proper tools for our customers. Having a solid understanding of the customer’s needs and requirements is crucial to providing the appropriate solution for their challenge. Issues are promptly solved when the customer, design team, and manufacturing are all working towards a common goal. At the same time, if all requirements are clear for all, the design and manufacturing processes can be streamlined which can reduce delivery times and cost. Outstanding customer service is the responsibility of all and not just one group.

Overall, speed and accuracy do not necessarily have to be a trade-off given that you have the appropriate tools, communication, and processes in place. With the growing market in the Oil and Gas industry it is paramount that accurate and rapid responses are provided to our customers. You can count on us to be prepared with a customized solution to any challenges you may be facing.

 

New Beginnings – The Story of an Immigrant Entrepreneur

Nicolas Rogozinski – Senior Technical Professional

Nicolas is a mechanical engineer with over ten years of experience in Oil and Gas as a field engineer for drilling operations, and seven years in new product development for casing equipment/cementing tools. During his career, he was involved in operations in the Magallanes basin located in the southern part of Chile/Argentina, offshore Norway, North American land, offshore Brazil and many more. He currently has seven U.S. patents, and he’s the author/presenter of several ASME and API papers regarding the deployment of equipment that he designed.

New Beginnings – The Story of an Immigrant Entrepreneur

As Citadel has recently eclipsed the 1-year mark, I have come to realize the similarities shared among Citadel’s core values and my experiences as an immigrant. This comes as I celebrate ten years of becoming a United States citizen.

I was born in Chile almost four decades ago to an air force pilot and a teacher. I had the privilege of traveling across the globe in my adolescent years. Out of all the places I visited, America impacted me the most. I was 12 years old the first time I came here. I witnessed the American dream in person, the spirit of entrepreneurship. Here you truly can do anything or be anyone that you chase after with everything you have. Growing up, one value my parents instilled in me was the value of a great education, so I worked to earn my education in America. When I was in high school, I did an exchange program in Evergreen, Colorado, eventually returning to study at the Colorado School of Mines pursuing a master’s degree in mechanical engineering.

Deciding to live and work in the United States after my education, I was able to relate with my grandparents who were immigrants just like me. In the early 1930’s, they immigrated to the southern part of Chile from Germany (hence the name Rogozinski). They were Christian missionaries and wonderful people.

They shared with me some of the struggles they faced when they uprooted their lives and started over. Stories when they started having their own families in a foreign land. These stories I had heard as a child became real to me as I experienced some of the same things with my own family. They also taught me values like integrity, entrepreneurship, life-long learning, and discipline that they embraced and helped them thrive as immigrants.

As I relive the last year growing with Citadel, I see those same core values my grandparents instilled in me are the very cornerstones of our company. As we grow, we are building on a foundation of integrity, hard work, and ingenuity.

Here at Citadel, we recognize the value of people – that the right team makes all the difference. So, when it comes to producing the best downhole components for cementing and casing running, Citadel has the best team players. Our team brings nearly 100 years of industry experience to our young organization. We have the knowledge and passion to meet customers’ requirements like has never been seen before.

 

Success Through Alignment

Ben Hollar – Rockies Account Representative

Ben is a Wellbore Isolation Expert with a focus on Casing Equipment and Cement. He graduated from Colorado School of Mines with a BS in Engineering. From there he has worked closely with operators to design and execute cement jobs around the world. Whether foam cement for complete losses in the Powder River Basin in Wyoming, remote operations in Bangladesh, offshore arctic in Alaska, or Bradenhead mitigation in Colorado’s DJ Basin – Ben has the knowledge and tools to help.

Success Through Alignment

Two questions: 1) What are your goals? 2) What can we do to help you achieve those goals?

Too often the goals of a service company are not aligned with that of the customer, which can only lead to disaster. Only when the entire team is standing shoulder to shoulder and headed the same direction will success be achieved. I say success because there are many wells that are completed, but few are completed successfully.

Again, what are your goals? How do you or your organization define a successfully completed well? Does that mean: A well completed with no safety incidents? Zero nonproductive time? No equipment failures*? What else? No formation fluid migration – anywhere? Casing and cement placed at targets? And the final goal of any project – return on investment? We at Citadel believe that through alignment of specific, attainable, and customer driven goals, every well can be completed successfully – maximizing ROI.

Let me set the stage for the second question… For Citadel, this means putting safety first. Working together to define goals and plan targets. Utilizing an industry top tier supply chain group to get equipment to location on time – every time. Designing and manufacturing products to the highest standard. Tactical use of the right technology to get casing to bottom and cement to the designed top. Finally, if the well is completed successfully we can confidently say that we upheld our portion of the return on investment equation.

Stand shoulder to shoulder with Citadel and allow us to help you achieve your goals: Success Through Alignment.

*Except those defined by the “Acts of God” clause (if you have set foot in the oil patch you know what I’m talking about). Plus, what good would an oil patch blog be without a bit of legal fine print?

THE MOST IMPORTANT TRAIT

Russell Tuncap – Controller

Russell is a Certified Management Accountant and a Certified Public Accountant (Texas) with over 20 years’ experience.  He earned his BBA – Accounting from Texas State University and his MS – Accountancy from University of Houston.  He is currently serving as President of the Institute of Management Accountants – Houston Chapter.  Russell is also a die-hard (read long-suffering) fan and booster of the Texas State athletics program.  Eat ‘em up Cats!

THE MOST IMPORTANT TRAIT

Over the years, I have been a part of several discussions about what the most important trait is that leaders and employees need to be successful.  An abundant list of key traits always come up, and all are critically important: technical skills, interpersonal skills, strong work ethic, integrity, industry knowledge, product expertise, strategic view, tactical execution, and the list goes on.  But I believe the single most important and valuable trait any employee can have, whether the company is an established leader, a company restructuring to survive, or a fledgling startup fighting for a foothold in the marketplace, is passion.

One of my co-workers has a sticker on his car that says “Eat, Sleep, Weld.”  I like seeing that kind of pride in a fellow employee!  To me, that says he loves what he does for a living.  He is passionate about his profession.  Passion for your career will carry you further in your field than just about any other trait.  With passion, you’ll have a natural curiosity about your profession.  You’ll grow your skills because you have a desire to know more about your profession.  You’ll come into work a little earlier or stay a little later, not because of other’s goals or deadlines, but because you love what you do.  You’ll think about improving your processes when your away from the shop or office, not because of other’s expectations, but because you’re passionate about what you do.  You’ll never see a champion who is ambivalent about their sport.  You’ll never find an expert who is uninterested in their field.  Champions and experts are who they are because they are passionate.

You’ve heard the saying, “Find a job that you love, and you’ll never work a day in your life.”  That is passion!  Whether your chosen career is management, sales, engineering, machining, welding, customer service, or accounting, passion won’t push you forward like a taskmaster.  Instead, passion will lead you, entice you, draw you, to be the best at what you do!  You’ll have the drive to find a better process, design a better product, manufacture with better efficiency, or better understand your customer’s needs.  At Citadel Casing Solutions, we are passionate about what we do, our customers, our products, and our people!

Best practices for shoe track drillout – 5 things to consider

Efficient shoe track drillout is essential to reducing nonproductive operations and resuming drilling new hole after casing runs as quickly as possible. Drilling out the shoe track is often troublesome as BHAs are typically designed to drill new formation, not the shoe track itself.
Even though many operators consider drilling the shoe track a duplicated effort (as no new hole is being drilled) it is an operation that must be performed after every surface and intermediate casing string is cemented before drilling can resume.

The shoe track is the space between the float or guide shoe and the landing seat of the cementing wiper plugs. Its purpose is to ensure that the casing shoe is surrounded by high quality cement, to keep the end of the cement from becoming contaminated with drilling fluid, and to provide a pressure indication via plug bump that the cement displacement is complete.

Drilling the shoe track can go smoothly in one well, and be problematic in the next. A recent study of 90 similar wells showed that a shoe track could be drilled efficiently in 2.3 hours, but could also take as long as 14 hours. It is important to understand the key factors that affect your ability to drill the shoe track quickly and effectively.

1. Drilling through the shoe track imparts left hand torque on threaded connections. Using a good thread lock system prevents casing joints from loosening while drilling out the shoe track. This also replaces welding on the bottom of casing joints, which can cause weakening from heat and chew up valuable rig time. Our Lok-N-Load™ thread lock product is battle-tested and comes in an easy-to-mix kit complete with base resin, catalyst and putty knife.

2. Competent cement jobs are important to ensure that shoe track components are not allowed to rotate during the drilling process. Fixed cutter bits (common PDC designs) drill best on stationary targets, and this can be achieved by selecting anti-rotation shoe track components, and achieving a quality cement job.

3. Optimal WOB and RPM must be determined to achieve maximum ROP. Lower RPM can help keep the shoe track components from spinning and aid in junk removal. A low WOB helps the PDC bit cut the drillable shoe track components more effectively, while keeping cuttings small enough for effective transport. It may take some experimentation to determine the best WOB and RPM parameters for your specific application.

4. Drilling shoe tracks with Rotary Steerable Systems (RSS) is becoming common place in horizontal shale wells, as operators are increasingly turning to RSS for drilling long lateral sections. Aggressive PDC bits are often coupled with RSS, which tends to create larger sized cuttings. These larger cuttings, when combined with the larger tool diameters of RSS can lead to plugging and bridging of cuttings in the annulus. If this occurs, a reduction in ROP may follow as weight transfer to the bit is affected.

5. Transport of cuttings will be affected by the cutting size, which is related to the aggressiveness of the PDC bit and the WOB applied. Flow rate, hole inclination, fluid parameters, RPM, and cuttings size are factors that affect cuttings transport. It is best to model these parameters using commercial cuttings transport software to achieve optimal transport.

In summary, drilling out the shoe track can be problematic unless many parameters are evaluated and understood. These key factors are:
• PDC bit type and style – cutter size and angle, blade layout and bit profile
• Drilling procedures – including WOB, RPM, and flow rate
• Cuttings transport – software simulations to best understand the relationship between cutting size, flow rate, and hole cleaning effectiveness
• Target materials being drilled – drillable, non-rotating components are preferred

By understanding the parameters that affect how a shoe track drills – along with a bit of experimentation and modeling, you’ll be able to design and implement a predictable, repeatable shoe track drilling program.

Some content for this blog was derived from the following technical papers. These can be found at www.onepetro.com.

Rogers et al., 2009. Costly Shoe-Track Drilling Practices Using Conventional and Rotary Steerable Systems
Evaluated. SPE/IADC 124368

Wiktorski et al., 2016. Shoe Track Drillout Analysis: Factors Affecting Drilling Efficiency. SPE-180011-MS

Citadel Casing Solutions produces innovative technology for cementing casing equipment. We create customer value through our unmatched engineering expertise, broad base of experience, and overall responsiveness. Our goal is to deliver the ultimate in wellbore integrity to protect our customer’s assets.

For more information on float equipment and other drillable shoe track products, email us at info@casingequipment.com

Dilemma: Process Versus People

Kurt Crowley – CEO

Kurt is a seasoned energy services executive with an intense focus on customer relations and project success. His experiences span business management, operations leadership and sourcing/supply chain responsibility for casing-related products and technologies.

 

Dilemma: Process Versus People

Throughout my career, I have experienced the evolution of business processes and their importance. From the days of hand written processes and procedures to the complex flow charts and decision trees that we see today. I firmly believe in the value of process and procedure because a systematic approach to the building blocks of an organization drives progress.

Processes enhance a critical level of compliance and risk mitigation and if managed correctly, can lead to operational success. Process also sets the expectation for employees and drives the overall goals and objectives of an organization no matter how small or large. Management is able to clearly communicate with the broader organization through process and procedure.

Unfortunately, in our haste to up the ante on streamlining and organizing our businesses with process and procedure, we sometimes lose sight of one simple fact. It is people that make the engine go. We as leaders have become so fascinated with the process flow that we have devalued the individuals behind the flow chart. People have become interchangeable cogs rather than integral to the process. Irony sets in at some point because without people, there would be no process or procedure to begin with.

True leadership recognizes the significant importance of having a strong team behind any process. My experience level in hiring a team has quickly taught me that losing a highly qualified employee is costly to the organization. Rarely have I found that replacing an individual was plug and play, not to mention the time spent and cost associated with finding the right fit.

We as leaders need to change our mindset going forward and balance the importance of process with having the right team of people. I have heard many times that I should “trust the process”. I say “trust your team members to develop and execute on the process”. Inefficiencies in processes will not shake out in a vacuum but a strong team will identify gaps quickly and efficiently.

Value your team and let them know that you care about them. That investment alone will return huge dividends by positively impacting compliance with process and procedure.

Just my two cents.

Casing Centralizer Selection 101

In any wellbore, it is critical to choose the right type of centralizer and to place those centralizers at optimum position on the casing to achieve good and consistent standoff. Casing centralizers are available in many shapes and sizes. It is important to understand the differences in each type and which is best suited to each application. In this blog, we cover three types of centralizers – rigid, bow spring, and unibody bow spring. These common styles cover a wide range of applications and are suitable for achieving high centralization performance.

Centralizers are used to keep the casing from contacting the borehole, while providing a good standoff clearance around the casing to aid running and cementing operations. In horizontal wells, centralizers need to have a high restoring force to support the weight of the casing, and a low running force to reduce drag. They also need to allow pipe rotation and reciprocation to aid in the casing running process, reduce differential sticking tendencies, and improve mud flow and zonal isolation while cementing.

Key Terminology

  • Restoring force – the force exerted by the centralizer to keep the casing away from the borehole wall
  • Standoff – the clearance between the OD of the casing and the borehole wall, normally quantified as a percent of concentricity
  • Starting force – the maximum force required to insert a centralizer into a specific wellbore or casing diameter
  • Running force – the maximum force required to move a centralizer through a specific wellbore diameter

Rigid Centralizers
Solid, welded blade centralizers offer high strength in horizontal and extended reach wells where rotation is needed to get casing to bottom. Rigid bars are welded to the centralizer collars, giving the design strength and durability. Rigid centralizers come in a variety of configurations, including hinged and slip-on, with both straight blade and spiral designs. Rigid centralizers are also available in composite materials which can reduce drag, enabling conventional casing runs in long laterals. Set screws are used in some configurations to lock the centralizer in place on the casing joint, providing extra holding force.  

Bow Spring Centralizers
This design is common in casing running operations offering a good balance between wellbore performance and cost. The spring steel bows are welded to rigid end collars that supply support to the bows. They are available in both slip on and hinged configurations to aid installation. Bow spring centralizers provide good borehole standoff, have favorable restoring forces, and come in a variety of shapes and lengths for most well requirements.

 

 

 

Unibody Bow Spring Centralizers
For horizontal wells with long laterals, tortuous boreholes, and severe well geometries (including high doglegs), a one piece, non-welded centralizer is the ideal choice. The unibody construction eliminates weak points. This means that the casing string can be rotated and reciprocated with more confidence when running to bottom in tight wellbore situations. During casing rotation operations, the centralizer is designed to remain in place, while the pipe rotates inside of it. This ability to agitate the pipe during cementing operations improves cement bond and long-term cement integrity. Unibody bow springs act as a semi-rigid centralizer, designed to be slightly under gauge minimizing drag while offering both flexibility and high restoring force. As the centralizer navigates restrictions, it is designed to compress and deform to a near-flat condition. As the borehole restriction is traversed, the centralizer reverts to its original form and shape without permanent deformation or damage.

About Citadel Casing Solutions
Citadel Casing Solutions produces innovative technology for cementing casing equipment. We create customer value through our unmatched engineering expertise, broad base of experience, and overall responsiveness. Our goal is to deliver the ultimate in wellbore integrity to protect our customer’s assets.

For more information on our line of centralizers for casing operations, visit us at www.casingequipment.com or email us at info@casingequipment.com

Casing Running Techniques for Extended Reach Wells

As operators design wells with increasing lateral lengths and longer horizontal sections, running casing to TD has become more challenging. The longer the lateral, the more drag and friction forces impede the process of pushing casing to bottom. The majority of today’s shale play wells use cased hole completions to optimize wellbore integrity and ensure the success of fracturing operations. Therefore, the prevention of downhole problems when running casing, and the need to get casing to total depth (TD) is extremely important.

Wellbore geometry is also a consideration when determining how to run casing to bottom and choosing the best method for reducing friction and drag. Typical horizontal shales well in the US have build rates between 6 – 12 degrees/100 ft. and are designed to reach the target formation with a minimal amount of Horizontal displacement (step-out) from the wellhead. This geometry increases the load put on casing at the heel of the well, and can result in buckling if drag and friction factors are excessive.

Several techniques have been devised to increase the chances of success on long horizontal casing runs. These include rotating the casing, adding buoyancy to “float” the casing to bottom, and employing devices to introduce axial vibration.

Rotating Casing to Bottom

Rotating casing to bottom changes the friction coefficient from one that is static to a dynamic component. The dynamic component is considerably less that the static component, allowing available casing weight to be used in penetration. In high drag scenarios, this method may require the use of torque-shouldered premium connections where the casing can be rotated under load without fear of joint failure. While there is an additional cost associated with using casing with premium connections, this can prevent unplanned connection failures during the running process.

Buoyancy Effect

The concept of floating casing to bottom is also a widely-used option. Casing floatation uses air or light fluid trapped in the lower section of the casing string to create a buoyant chamber on the casing’s lower end. This can significantly reduce the casing weight resting on the wellbore, reducing drag and friction during the casing running process. The length of the buoyant chamber can vary based on the reduction in drag required to successfully run the casing to TD. The inability to circulate through the casing prior to reaching TD is a major limitation of this technique. The wellbore must be well conditioned prior to running casing to avoid issues presented by static mud gelation. If a washout, ledge, hole collapse, or sloughing shale is encountered, it may prove difficult to pass even with the benefit of floatation.

Axial Vibration

To overcome the challenges with getting casing to bottom in horizontal wells, new tools are being introduced that induce downhole axial vibration to overcome friction. This concept has been widely used successfully in both coiled tubing and rotary drilling applications and greatly reduces the frictional forces between the drillpipe or coiled tubing and the wellbore, while improving toolface control, sliding ROP, and extending bit life. In casing applications, introducing axial vibration reduces the forces while running casing, allowing higher doglegs to be traversed, and longer laterals to be cased completely and quickly. Operators have also seen improvements in cement integrity, as the vibration during casing running operations improves cement flow and the uniformity of cement placement, reducing voids and channels.

Citadel Casing Solutions has partnered with Thru Tubing Solutions to provide the proprietary Casing XRV™ tool for extended reach horizontal wells where casing running may be problematic. This tool is positioned in the casing string near the shoe, and is designed to induce substantial axial vibration to reduce friction forces and improve casing running ability. As fluid flows through casing and the Casing XRV tool, a fluid pulsation is created at the tool’s exit point. This changes hydraulic loading at the end of the casing, creating a continuous fluid hammer effect that improves casing installation. An added benefit of utilizing the Casing XRV tool is the improvement in cement integrity by reduced voids and channels as a result of the induced vibration. The Casing XRV is also not flow restricted prior to reaching TD as is floatation, allowing circulation while running in hole.

The robust and reliable Casing XRV tools incorporate no moving parts, and contains no elastomers. It is available in a wide range of threads and sizes. Larger sizes are made of drillable material, and can easily be drilled out by conventional PDC bits. In today’s horizontal wellbores, integrating the Casing XRV tool into your casing program can significantly reduce problems with getting casing to bottom, while improving the quality of the cement job.

About Citadel Casing Solutions

Citadel Casing Solutions produces innovative technology for cementing casing equipment. We create customer value through our unmatched engineering expertise, broad base of experience, and overall responsiveness. Our goal is to deliver the ultimate in wellbore integrity to protect our customer’s assets.

For more information on the Casing XRV, email us at info@casingequipment.com

Achieving cement plug success on the first attempt

There are several reasons to place a cement plug – from plugging the well back for a sidetrack, preparing for a kickoff, well abandonment, or for curing a lost circulation zone. Successful cement plugs are rarely quick or easy. Placing a cement plug in an open hole horizontal well is especially difficult. Additionally, as most open hole plugging operations are unplanned, it’s essential that nonproductive time is minimized and that drilling gets back on track as soon as possible.

In a technical paper published by the Society of Petroleum Engineers (SPE 113092*) the authors found that an average of 2.4 attempts are necessary to achieve a successful sidetrack. With each plug attempt consuming between 24 and 48 hours of rig time, well costs can increase dramatically. Among the problems identified as factor of plug failure include: plug slippage, plug or slurry contamination, and insufficient cement wait time before attempting to drill the plug.

Common practice in setting a plug in open hole is to use a workstring to place a cement slurry, forming a plug and wellbore seal. The workstring is tripped into the desired depth to the bottom of the plug, then a cement slurry is pumped down the workstring and into the annulus between the workstring and the wellbore. The workstring is then tripped out leaving the cement slurry to harden, thereby forming the seal. However, in horizontal wells, as the workstring is pulled through the slurry, the slurry often is pulled uphole, resulting in stringers of cement and a less-than-competent plug.

Determining the correct slurry transition time from liquid to solid is challenging. If the slurry hardens too fast, the workstring could become stuck in the wellbore. If it doesn’t harden fast enough, the plug could become contaminated or move as the workstring is pulled due to wellbore swabbing. Additionally, a slow-setting slurry can slump in the horizontal wellbore, thereby preventing the plug from properly isolating the wellbore and zone.

To solve this problem, plug placement aids have been developed that allow sacrificial tubing to be left downhole at the completion of the plug job. This allows the workstring to be disconnected from sacrificial tubing at the top of the cement plug and tripped out without disturbing the slurry, and without worry that the workstring may become stuck. These tools also allow longer plug lengths to be pumped at the same time rather than setting multiple short-length plugs on top of one another. Additionally, higher performing cement slurries can be used with much faster cure times, higher viscosities, and higher yield points.

These mechanical devices typically employ a wiper dart that is pumped down the workstring which latches into the disconnect assembly when cement is fully displaced. This creates a pressure increase which activates a sliding sleeve, allowing the disconnect to take place. The tailpipe can be made of drillable composite material, and can be drilled out along with the cement plug if continuing operations are required.

However, no mechanical device is trouble free and fully dependable in deviated wells or short plug lengths where sufficient tailpipe weight is not available to assist with separation. What if the required overpull to disconnect is greater than the sacrificial string weight? Do you wait to achieve cement gel strength to pull against? Do you risk pulling on the cement plug? While the industry has been accepting of this potential failure mode in the tool design, Citadel Casing Solutions recognized this shortcoming and engineered a solution.

The PreNup Plug Placement aid is run in hole on drill pipe or tubing with sacrificial tail pipe below.

After being released by a dart, the drill pipe is free to be removed from the well, leaving the tailpipe and a formidable cement plug behind.

Citadel’s PreNup™ line of plug placement aids make complicated separations a thing of the past. The tool includes a pump-off feature that enables hydraulic disconnect with the sacrificial tailpipe by applying pressure rather than overpull from surface. This feature eliminates the risk and anxiety of moving the sacrificial tailpipe through the cement plug, or failing to release entirely during release operations. Now cement plug setting can be accomplished accurately and efficiently on the first attempt. Protect the assets you’ve worked hard for with the PreNup™ Plug Placement Aid.

*Al-Yami et al., 2008. New Cement Systems Developed for Sidetrack Drilling. SPE-113092-MS

About Citadel Casing Solutions

Citadel Casing Solutions produces innovative technology for cementing casing equipment.

We create customer value through our unmatched engineering expertise, broad base of experience, and overall responsiveness. Our goal is to deliver the ultimate in wellbore integrity to protect our customer’s assets.

For more information on our PreNup™ plug placement aids, visit us at www.casingequipment.com or email us at info@casingequipment.com