Case Study: Coiled Tubing Drilling, Kurapak Oilfield, North Slope Alaska (SPE 168250)
Author: Marat Seitimov
Published: 1st July 2020
North Slope Alaska can boast one of the largest numbers for wells drilled using Coiled Tubing Drilling technology. As redevelopment of the Alaska fields continues, horizontal limits are pushed to even greater maximums.
Kuparuk oilfield is a mature field on the North Slope that features thin, highly faulted reservoirs, making the CTD an instrumental technology to drill horizontal multilateral thru-tubing completions.
In October 2012, a well was drilled using MPD techniques. The well was a tri-lateral injection well drilled to the south to support a production well in the area. It was planned to drill an open hole section of 8143’, with 4318’ laterally. Laterals were all completed using a 2-3/8” slotted liner.
There were several challenges associated with drilling this well, particularly, formation pressure management was more challenging due to absence of reliable data regarding the pressure in the southern-most fault blocks. The estimate was about 9.8 ppg but it was not possible to confirm this. The near wellbore pressure was about 12.6 ppg. Using these estimated values, an ECD operating envelope was constructed, which allowed the ability to determine the maximum permissible annular friction pressure. The borehole size had to be increased to 3.25” from 3.00” which was originally planned.
The first lateral was a record-breaking length of 4,293 ft of openhole at a TD of 13,375 ft MD. Nonetheless, this was not without obstacles as heavy losses were encountered. The initial estimate of 9.8 ppg suggested that formation breakdown could happen above 13.8 ppg EMW. However, circulation was lost at just under 13.8 ppg, suggesting that the estimate should have been closer to 9.6 ppg.
Another challenge was running the liner completion. Due to heavy fluid losses, the liner running pill was lost to the formation, increasing drag and causing the lock up at 13,028’ MD, 347’ short of TD. The operator re-assessed the drilling parameters before going onto the next two laterals to avoid similar complications. It was decided ECD would be lowered in the openhole by adjusting mud properties and pump rate. This modification resulted in zero losses when drilling the subsequent laterals.
The laterals were drilled using a very low AKO on the drilling motor (about 0.5° AKO) with a bi-center 3.25” bit. Average doglegs were resulted in 6-8 deg/100ft. Even though, a cumulative dogleg was consistent with the directional plan (7° DLS), the actual drilled trajectory and the planned trajectory ended up being very different. Nonetheless, the project was successful with all laterals hitting target zones. This project expanded capabilities of extended reach lateral drilling on Coiled Tubing and provided additional insight to areas that required further development and work.
Image: Nabors CTD-3
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Toni’s business focus remains the same today as it was when he founded AnTech in 1992: to lead a thriving, ambitious company that brings value to customers through engineered solutions. He is the driving force behind AnTech’s product development strategy and, more recently, the move into coiled tubing drilling services. His ability to design and innovate is reflected in the fact he is named on 17 patents. Toni has over 35 years of industry experience, starting his career with Schlumberger and serving in both field and engineering positions. He has a degree in Mechanical Engineering from Imperial College London, is a Chartered Mechanical and Electrical engineer and a Fellow of the IMechE.
CHIEF EXECUTIVE OFFICER & FOUNDER
SENIOR VICE PRESIDENT NORTH AMERICA
John brings unparalleled experience to support our customers in North America. He has spent over 45 years working in the oilfield industry and highlights include the invention of continuously tapered coiled tubing used by coil operators across the globe. He has previously worked for NOV Quality Tubing as the SVP of Product Development and Baker Hughes as the Technical Director & International Operations Manager. He is one of the founding members of ICoTA and supports a wide range of organisations including SPWLA, SPE, AADE and IWCF. John holds a BS.degree in Electrical Engineering with a minor in Physics from Kansas State University.
Jenny leads on the delivery of tools and support for AnTech’s Products and Services divisions, ensuring they are shipped on-time and to standard. She has been part of AnTech for over 20 years and has served in most departments, including a period as General Manager. Jenny is a Chartered Engineer with a degree in Electronic Engineering from Birmingham City University. She is a Member of the IET and IOSH qualified. Jenny devotes a significant amount of her free time to support HCPT, a charity that works with children with special needs, some of whom are terminally ill.
HEAD OF PRODUCTION
As Operations Manager, Adam’s role is to deliver AnTech’s services safely and efficiently and he is committed to working with customers and service partners to ensure the promised value is realised. Before joining AnTech, Adam worked as a drilling engineer for BP in Aberdeen and, as lead engineer, demonstrated his ability to bring projects in on time and on budget without incident. He has served on the SPE Aberdeen YP Committee. Prior to that, he worked for a short period with Halliburton. Adam graduated from Imperial College London with a First Class Master’s degree in Mechanical Engineering.
GLOBAL OPERATIONS MANAGER
HEAD OF GLOBAL SALES & MARKETING
Clare Miszewska-Hall is the Head of Global Sales & Marketing and leads AnTech’s business development activity, sales strategy, and the creative direction of the business. She has been instrumental in establishing AnTech's Coiled Tubing Drilling services, enabling oil companies to economically extract more value from their existing assets. Before joining AnTech, she worked in the FMCG sector in a variety of engineering and marketing roles. Clare’s expertise has been key to strengthening the AnTech brand and the launch and expansion of CTD services in the ME and USA. Clare holds a First Class degree in Mechanical Engineering from Cardiff University.
Ben is the principal architect of the electronic and software developments in AnTech’s tools and is named as an inventor on AnTech’s gyro patent. His designs are based on experience gained during field trials of equipment he has developed, which means they reflect real-world requirements. He developed, and is responsible for, AnTech’s product lifecycle management system, a role he embraces as it ensures he can drive AnTech’s commitment to product excellence. Ben has a First Class Master’s degree in Electronic Engineering from Exeter University and is a Chartered Engineer.
HEAD OF ENGINEERING
Carly’s strong commercial understanding and systems expertise ensures that finance plays a pivotal role within the company and can offer valuable and informed strategic input. After graduating from the University of Warwick, Carly trained in accountancy with Grant Thornton as a Chartered Certified Accountant before making a move to the corporate sector. Before joining AnTech she was part of a successful senior management team at Kaba Limited UK, a leading security solution and manufacturing company.
HEAD OF FINANCE
Increase the range of services you can offer to your clients by offering them Directional Coiled Tubing Drilling (DCTD). We will provide all the drilling expertise that you need to be able plan and execute a drilling job using your existing CT assets. Working in partnership with you, we can offer a winning solution to all stakeholders.
Because CT technology is all based around pressure control at the wellhead, underbalanced drilling with coiled tubing is a far more efficient method than using the more conventional, rotating head technology from a standard jointed pipe rig. In fact CTD is the only technology that can ensure that underbalanced condition are maintained at all times. Your existing expertise with dealing with wellhead pressure can be applied to underbalanced drilling whereas a regular drilling crew needs to upskill to do the same task.
WHAT WE DO
- AnTech Integrated Management (AIM) Service can provide you with full integrated project management services and be the one point of contact for the operator if required.
- Our proprietary and patented CTD BHAs can drill hole sizes between 3-5/8” and 8-1/2”. We also provide the surface equipment to maintain the tools on location and data acquisition systems to run the BHAs.
- Feasibility modelling, our proprietary ATLAS software for CTD modelling predicts parameters such as well paths, tubing forces (WOB) and hydraulics (hole cleaning).
- Our Products Division can provide you with a complete conversion kit to make your CT unit completely wireline enabled.
- We can offer you and your team dedicated CTD training at your facility or at the customer’s location.
WHAT YOU DO
- Provide the rig or CT unit and crew
- Provide the e-coil, the wireline can be installed by a Coiled Tubing manufacture before shipping or on location if required. We would require a 7-conductor heptacable and we generally run coil sizes from 2-3/8” to 2-7/8” depending on the well profile.
PARTNER WITH US
We will provide you with a detailed pack required to integrate our equipment.
Site visit from one of our engineers to scope out STEP 2 in more detail, for example, where our data acquisition panel will sit within your coil cab.
If you would like to know more about Coiled Tubing Drilling or if you have a project that you think could benefit from our service, please do not hesitate to get in touch.
Our BHA Technology
INDUSTRY CTD CASE STUDIES
We provide the BHA & Project Management
You provide the coil and
YOU ALREADY HAVE A LOT OF THE EXPERTISE REQUIRED
YOU ALREADY HAVE THE EQUIPMENT
Long term CTD projects often use dedicated rigs or combine the ability to handle coil and jointed pipe in a hybrid format. But regular CT rigs with a mast, tower or simply a crane deployment can be used effectively.
Your clients, like all operators face the challenge of declining production on all their wells. Drilling horizontal laterals from existing vertical wellbores, of which there are many, helps them to extract more oil and gas from existing reservoirs. More than they may think is possible if they have only considered regular overbalanced drilling.
Partner with us to offer new service to your clients. We will support your sales force to create a winning offering for all concerned.
Coiled Tubing Drilling vs Conventional drilling: Don't compare apples with oranges
People sometimes say to us ‘Why drill with coil when I can get a cheap jointed pipe rig to do the same job’. In answering, it’s important to be clear what the ‘same job’ means. If the objective is simply to drill hole, then a regular rig might be better. But if the objective is to drill a hole, do it efficiently and do it without damaging the reservoir than underbalance drilling with coil has no equal.
Our Directional CTD BHA’s run on regular 7-conductor wireline inside coil of between 2-3/8in and 2-7/8”. Coil can be ordered from the mill with the wireline pre-installed.
We can provide the necessary conversion kit to terminate
the cable at each end and hook the wireline to our Albacore surface data acquisition system.
Share photos and specifications of your CT unit with us.
Talk to us. We can help you screen opportunities. Not every drilling opportunity is suitable for CTD either because of well geometry, its potential production or geology. Some wells can turn into stars, some will never produce enough extra production to warrant an intervention.
YOU ALREADY HAVE A LOT OF THE EXPERTISE
HEAD OF HUMAN RESOURCES
Martin is key to ensuring AnTech has the team in place to achieve its growth strategy in the short and long terms. His background is in international talent acquisition and management with Sitel and then Novell where he was the EMEA HR Manager. He also ran his own business for 10 years. Martin has a Postgraduate Diploma in Human Resources Management from Kingston University.