June 2024

Well decommissioning: Simple solutions to complex problems

Traditionally, barrier testing and subsequent validation by a technical authority can sometimes rely on personal observations and subjectivity. HydraWell looks to strike a successful balance of its values while pushing boundaries and inventing pioneering technologies that will transform well integrity management operations around the world.
Alan Quirke / HydraWell

Recently, I wrote, “Do complex problems need complex solutions, or can we implement simple low-cost solutions when solving complex problems? Are we persistently looking for quick, easy and simple ways to solve our problems while (paradoxically) excessively complicating the problems facing us?”   

Since the company’s inception in 2010, HydraWell has been focused on understanding the problems faced by well owners during well integrity, slot recovery and well abandonment operations. Delivering simple, cost-effective solutions starts with developing a greater understanding of the challenge faced, which historically has been presumed to be complex and unwieldly. Problems were considered too cumbersome to warrant the implementation of novel, simple and straightforward solutions. 

Installing barriers in wellbores, to permanently isolate zones of flow potential or remediate incomplete barriers installed during well construction, is a significant problem for the wellbore management industry, in the hydrocarbon extraction, salt well and even geothermal sectors. Keeping vent flows and emissions permanently contained without incurring excessive time or financial costs has been an aspiration for all well owners—particularly at the end of well life.  

Traditional methods of solving the problem were often derived from the idea that a complex problem required a complex solution, and this becomes associated with high technical risk, cost uncertainty and, more recently, significant carbon emission intensity, resulting in inaction and acceptance of the status quo for another period. The perception that the challenge is complex prevents the implementation of a simple solution, exacerbating the risk profile and stalling progression. 

The introduction of HydraWell’s Perf-Wash-Cement (PWC®) barrier remediation and installation methodology has changed the perception that complex solution capability is required to solve the well barrier placement challenge. The methodology has revolutionised the process of barrier placement in the well construction and abandonment sectors.  

By understanding the challenge, employing a scientific approach to barrier design and demonstrating confidence in outcome before operations commence, HydraWell has changed the paradigm and drastically reduced the cost, support requirements and carbon footprint of well barrier placement operations. Being the simple solution, our PWC® is not only more cost-effective for the well owner but also safer and better for the environment. 

The defining concept behind the system brought to market over the years is to wash and prepare the wellbore annulus behind a perforated section of casing, to clean out debris or poor cement before re-installing fresh cement or another plugging material across the treated interval. This ensures the wellbore is plugged, and flow potential is isolated in perpetuity. The name Perf-Wash-Cement (PWC®) is derived from the operational steps required to gain access to, prepare and then install barrier material behind in-situ casing in the wellbore, Fig. 1.  This revolutionary methodology provides a nimble, flexible and cost-effective method, which is much in demand across a range of applications—from slot recovery to permanent plug and abandonment, restoring annular integrity and casing shoe repair. 

Fig. 1. The name Perf-Wash-Cement (PWC®) is derived from the operational steps required to gain access to, prepare and then install barrier material behind in-situ casing in the wellbore.

As early as 2010, the company introduced the first generation of HydraWash™ and its cup-based, low-pressure cement remediation system to the market. The system was designed to mitigate the high risk, replace material cost and time-consuming alternative methods for getting access to isolated zones of flow potential. Successfully deployed in wells with poor or no cement across the annulus, the system was adopted by those clients who recognised the time, cost and efficiency benefits offered by the methodology. 

The legacy of HydraWash™ remains woven throughout the company’s offerings more than a decade later, and it formed an important base from which we were able to create the second-generation PWC® system, HydraHemera.™ 

With the limits of the first-generation system realized, and with an improved understanding of clients’ needs, a new generation of tools was developed in 2015. The HydraWash™ system was licensed to other service providers, and HydraWell was developed and progressed to the more versatile jet-based PWC® system marketed under the HydraHemera™ banner. 

HydraHemera™ was deployed for implementation across a much wider range of applications, targeting multiple annuli in more-challenging, higher-inclination wellbore environments. The high-pressure, technically superior jet-washing tool, cultivated for the same applications as its predecessor, became the solution of choice in single and multiple casing applications.  

Thanks to enhancements offering simpler deployment, greater efficiency and benefits—which include the ability to maintain full circulation rate—the HydraHemera™ system quickly became recognized as an easier, more predictable system to deploy.  It overcomes risk associated with exerting excess pressure on the formation by not relying on “limited entry” to force fluid through all perforations. With delivery of a 98% plugging success rate, customers know that HydraHemera™ gives confidence in a predictable outcome. 

In a recent example, HydraWell successfully expanded its geographic horizons, when the team was engaged to deliver an advanced solution to plug and abandon a subsea well, which did not include section milling, in an aging field (installed during 1976) in Brazil. As well as navigating the challenges associated with working in the Brazilian basin, the campaign’s requirements were to deliver a robust, time-effective and predictable service to keep costs as low as possible while minimizing environmental impact. To comply with both internal and governmental regulations in South America, a rock-to-rock cement barrier was required in the cap rock above the reservoir. 

HydraWell mobilized specialists to oversee the deployment of HydraHemera,™ with the jetting tool used to wash and clean out debris in the annular space behind the casings, creating optimum conditions prior to placing the plugging material across the entire length of the required sections. Debris, old mud, barite and old cuttings were replaced by clean mud and spacer fluid. 

The campaign—focused on verification by demonstration—required that the installed cement plug be drilled out and evaluated by logging, to confirm the suitability of the barrier installation method before the HydraHemera™ methodology was accepted by both the client and regulator. 

This latest campaign in Brazil has cemented HydraWell as a global market leader in P&A applications, as the company continues to design superior solutions that are carefully aligned with the needs of our clients in expanded geographies. As a result, a new partnership was forged with a customer in a new target geography, and HydraWell became one of the first companies, globally, to have contributed to the launch of the decommissioning market in South America.  

By tapping into this rapidly growing market, HydraWell is now delivering a quality, sustainable solution that maximizes safety and reduces carbon emissions. We also are fostering new partnerships for future decommissioning campaigns between Europe and South America. 

Innovation did not stop with remedial wellbore activities, Fig. 2. Developing a method for reliably testing in-situ barriers, squeezing shales, squeezing salts (commonly known as GeoSeals) and subsequently isolating the wellbore internally was pioneered by HydraWell in 2015, with the introduction of the annulus integrity test (AIT) tool. 

Fig. 2. Innovation did not stop with remedial wellbore activities.

Post-perforating, the integrity of the AIT is verified in blank casing before the cups are positioned across the lower perforated interval. Pressure is applied between the cups to test the integrity of a suspected surrounding formation. If it is competent—i.e., no return is observed through the upper perforations—formation is squeezed onto the casing circumference, and the barrier is verified. Testing with an AIT can be repeated to confirm the initial test or moved in the wellbore to test a secondary area. Post testing, an internal cement plug can be set, or the tool can be retrieved, depending on the next operational steps to be performed. 

A subsequent drive to increase the operational envelope of jet-based PWC™ and address more challenges from a growing global customer base gave rise to the HydraTyphon™ PWC™ tool. The tool was developed to address more challenging barrier placement applications, with a specific focus on larger casing sizes (11 ¾ in. and larger) set in a heavy or high-viscosity fluid environment. 

Simultaneously, and against a backdrop of HydraWell’s 500th plug installation in 2023, a further advancement in the portfolio saw the introduction of HydraCT,™ Fig. 3. As its name suggests, HydraCT™ enables PWC® operations to be conveyed by coiled tubing or small jointed pipe, opening up a new set of opportunities for well owners to install wellbore barriers thru-tubing, while remaining true to the already established PWC™ barrier installation principles and methodology. Specifically designed for low-footprint rigless applications, HydraCT™ has the potential to cut CO₂ emissions during barrier placement activities by almost 80% and reduce installation costs by up to 60%. The significant step forward that this represents, in terms of eliminating the need to mobilize a rig to site, is considerable, and it comes from an unstinting desire to do new things. 

Fig. 3. HydraCT™ is an industry first for rigless abandonment using conventional barrier materials.

As an industry first PWC® system for rigless abandonment using conventional barrier materials, HydraCT™ uses the fluid energy to not only penetrate and remove debris in the annulus space but also as a propellant, creating a rotational force downhole that replaces the requirement to rotate the entire workstring from surface. During the cleaning of the casing and annulus, wash fluid is circulated through the coiled tubing to the tool that incorporates a hydraulic brake. As fluid exits the tool, the flow introduces rotation, facilitating the formation of turbulent vortex flow, which cleans the annulus with multi-directional nozzles, focusing the high energy jetting force and displacing annulus content with the fresh wash fluid. 

The benefits of the HydraCT™ PWC™ system were recently appreciated during the annular isolation and P&A of 11 wellbores in Alaska, Figs. 4A and Fig. 4B. The project needed a more cost-effective method for use in a remote area, where rig availability is extremely limited. In a single run per well, HydraCT™ eliminated the need to mobilize a rig to site and cut the requirement to run drill pipe for remediating the annuli without compromising barrier quality or barrier verification—all in less than 24 hrs for each well, Fig. 5. 

Figs. 4a (left) and Fig. 4b (right). HydraCT™ offered a more cost-effective method in a remote location.
Fig. 5. HydraCT™ elimates the need to mobilize a rig.

In support of industry’s drive towards de-risking operations prior to execution, HydraWell—with client support—collaborated in the development of “digital twin” computational fluid dynamic (CFD) modelling for barrier remediation and installation in wellbores. CFD is a branch of fluid mechanics that uses computational power to perform the complex calculations required to simulate the free-stream flow of fluid and the interaction of that fluid with surfaces, as well as the environment through which it is flowing. In 2016, HydraWell began utilizing CFD to simulate fluid flow and pressure dynamics in wellbores— specifically, within an annulus for remedial barrier placement and verification. The method's ability to model complex geometries, fluid properties and dynamic conditions generates a comprehensive understanding of fluid behavior within the wellbore environment. 

Today, confidence in barrier placement capability and the need to verify that placed barriers are fit for purpose are two key aspects in determining the successful decommissioning of wellbores “in perpetuity.” The use of CFD in a digital twin environment helps pre-determine those outcomes, optimizing the barrier placement process and ultimately assisting in verifying the suitability of the placed barrier. Ensuring effectiveness of the operation and the placed barrier in a virtual environment, by replicating actual conditions, allows the well owner to confirm that an operation delivered, as planned, will prevent unintended fluid migration between geological formations and the surface. Verification by CFD is a significant advancement over traditional verification methods, which involve mainly non-empirical methods. Traditionally, barrier testing and subsequent validation by a technical authority can sometimes rely on personal observations and subjectivity to determine the effectiveness of a placed barrier. 

Evolving technology, understanding of the limits of subjective assessment, and recognition of a potential knowledge gap in a growing well decommissioning industry validate the scientific approach to ensuring barriers are designed, installed and verified with confidence. 

So, there really is strength in using everything we have learned to develop our portfolio. It has grown and evolved in new and exciting ways over the years and will continue to do so, driven by a common aim of trying to prevent vent flows and unintended hydrocarbon releases from abandoned wellbores.  

With a portfolio remaining firmly focused on achieving optimum results, HydraWell will continue to strike a successful balance of remaining true to its values while pushing boundaries and inventing pioneering technologies that will transform well integrity management operations around the world. 

About the Authors
Alan Quirke
Alan Quirke has 30 years of experience in the oil and gas industry, focused on well management, and he is currently CCO of HydraWell. Previously, he served as Head of Wells for Repsol/Sinopec UK, where he was responsible for design, construction, maintenance and abandonment for the organization’s full well portfolio. He holds an MBA degree in oil and gas management and a bachelor’s degree in electronic engineering.
Related Articles
Connect with World Oil
Connect with World Oil, the upstream industry's most trusted source of forecast data, industry trends, and insights into operational and technological advances.