This panel discussion, session 8C, was held on Wednesday 26th October 2022. The moderator and chair John Litynski of US DOE FECM welcomed four panellists in discussing the repurposing of existing infrastructure.Tony Espie (BP), Bente-Helen Leinum (DNV), William Van Geertruyden (Exxon Mobile) and Sarah Leung (US DOE) provided insights and perspectives from their experience. They started with an overview, then answered three questions posed by the chair, and wrapped up with an open question session from the audience.
Tony Espie (BP), has worked on repurposing and requalifying assets since the mid 1990's and kicked off the discussion, stating that we all like the idea of repurposing, but what are the main issues to contend with as we start to assess assets? These include infrastructure – pipelines, platforms and wells, and data – a range of rich datasets and operating history that is not always easy to get hold of but can provide evidence that you have seal and reservoir quality. There is upside potential for additional revenue streams – with incremental recovery and deferred abandonment costs.
He fleshed out some issues that were critical to have a handle on: potential leak paths (exploration, appraisal, production, and injection wells); geo-mechanical history (depressurisation and repressurisation); potential for Joule-Thompson cooling (where CO2 is transported at high pressure in the dense phase and injected into a low pressure reservoir and has implications for well integrity); and liability management – particularly when there is a change of operator.
What are the key priorities to ensure the potential for re-use? Thinking and planning for transition earlier rather than later seems to be the main message. For example, prior to well abandonment and the timing and status of field depletion. Maintenance regimes for facilities, wells and pipelines are critical as are data management and preservation.
Bente-Helen Leinum (DNV) has a wealth of experience with pipelines and emphasised the value of industry standards and guidelines when building new and reusing existing pipeline. The industry has a long history in designing pipeline on and offshore and assessing integrity - it's just the fluid that has changed.
There are already a set of design standards in place with DNV (2010) and ISO (2016) standards. The requalification process should comply with same requirements as those for designed pipelines especially for the transportation of CO2. DNV have published a recommended practice document for the design and operation of CO2 pipelines. Robust guidance on the safe management of pipeline infrastructure can establish trust and confidence between stakeholders, authorities and society.
However, one of the limitations can be access to the original specification documents, the rules state you are to keep the documents for 10 years, however for a 30 year old pipeline these documents may not be kept which makes repurposing less straightforward. Another key consideration is the phase of CO2 transported, CO2 in the gas phase is more similar to natural gas than the dense phase, this may be critical if there is a maximum operating pressure for an existing pipeline however there is a drawback of the transportation of lower transfer capacity. Other factors need to be considered when repurposing a pipeline to transport dense phase CO2 such as corrosivity, temperature, dry ice formation and the capacity to withstand running fractures.
William Van Geertruyden (Exxon Mobile) summarised Exxon Mobile's proven track record in CCS, with over 30 years developing and deploying CCS technologies at scale. Exxon Mobile have a large stake in global capture projects and have captured ~40% of the anthropogenic CO2. Low carbon solutions is a new business line (2021) with CCS a critical part. One such project is LaBarge, Wyoming CCS facility (1986) which has a current capacity of 7Mt CO2/yr. The customers are primarily for EOR, this is set to expand with $400mill project to at least 1Mtpa.
In order to consider repurposing infrastructure for transport and storage William advocates thinking about the full system using a risk-based approach. Current materials are designed for pressures and temperatures appropriate for hydrocarbons. Echoing Bente-Helen's comments – CO2 is a different medium to be transported and stored. CO2 composition and impurity limits will be critical. Carbon steel will likely be basis for majority of future infrastructure needs for transport and storage. Codes and standards will need to be developed or updated to accommodate new opportunities, and innovation in technology and business models will be key to overcoming those challenges.
Sarah Leung (Program Manager of carbon transport and storage at US DOE) emphasised the tyranny of distance "as we seek to connect the storage and sinks, we need to be thinking about the assets we have today and the build out of new infrastructure, so we don't have stranded assets". She presented the milestones necessary to achieve the US decarbonisation goals starting today through to 2050. With modelling results of the pipeline requirements to do so, with 5,300 miles of pipeline today, 11,000 miles in 2030 and >25,000 miles required in 2050.
In February 2022 US DOE FECM ran a workshop to connect industry, professional associations and other governmental stakeholders to talk about technical R&D, policy and regulatory challenges in repurposing pipelines and wells for carbon transport and storage.Objectives included exploring technical advancements, operational considerations, RDD&D gaps, and regulatory considerations. The outcome was a report published (available on request) and included recommendations to identify the research and funding needs.
Sarah provided an update on the status of US regulations. The Bureau of Ocean Management (BOEM) and the Bureau of Safety and Environmental Enforcement (BSEE) are currently updating offshore regulations for the geological sequestration of CO2 on the Outer Continental Shelf as directed by the Bipartisan Infrastructure Law. The EPA's guidelines on the transitions of class II wells to class VI wells is well established, and being appropriated. US DOE also working with Department of Transport Pipeline and Hazardous Materials Safety Administration (DOT PHMSA) who are initiating new rulemaking to update standards for CO2 pipelines. Other DOT entities include rail (Federal Railroad Administration) as we already move CO2 by rail and the Maritime administration (MARAD) as we seek to move offshore. Also included in conversations is the US Coast Guard as there will be a need to transfer CO2 from onshore to ship and the coast guard looks after port security.
Lastly, Sarah reviewed the current funding opportunities supporting repurposing infrastructure, including elements within the Bipartisan Infrastructure Act and Inflation Reduction Act.
The chair then posed a series of questions to the panellists:
1.Comment on CO2 specification requirements for existing (H2S and other impurities) purification requirements that might affect the economics of a project? What benefits are there to setting standards that broaden the access for other users of infrastructure and storage facility?
Key challenges in dealing with impurities – main issues are the phase behaviour and thus flow behaviour that alters with impurities, and also the corrosion of the steel and therefore the integrity. For example, in the case of Northern Lights they will connect to a variety of sources and then the impurities questions will arise, this will be true also of Hubs. There is a need to extend the specification and guidelines. There is research going on, e.g. IFE for the past 30 years.
Wells are corrosion resistant so can probably handle the impurities however understanding impact on surface facilities will be critical. However, there are issues of cooling with the wellbore, potential for slugging, and hydrate formation – they need to be assessed and evaluated by change in composition.
There are some legal constraints about what can be stored offshore, London convention states what can be stored. There were concerns raised at the time, if the CO2 was permitted it might open the door to dispose of more toxic materials – so if looking at co-disposal you would get push-back on allowing storage. London convention states – 'overwhelmingly CO2' – intended to recognise you may not get 100% CO2. DOT PHMSA - CO2 90% or greater is allowed.
2.A significant amount of data on the existing fields and their performance during production exists. How can we leverage that but also what data may be needed as we transform the field production to injection operations?
Bente – for requalification you have what you have (e.g. design criteria). It's important to fit your business case to your pipeline. In terms of general documentation, most companies have good control, but if there is a change of operator data may get lost in the process.
Tony – subsurface data becomes important. It's not always easy to predict dynamic systems, real performance usually has surprises. A range of boundary conditions exist, that become ultra-important. Most people think of constant stream of CO2, but at Hubs there will be fluctuations in rates and compositions.
3.There are a number of opportunities to develop storage resources adjacent, below or above producing oil and gas assets. What technical and legal challenges does this pose for project developers?
Sarah – that was part of the discussion in the February workshop, one of the unique challenges is pore space ownership in US but might not be present elsewhere, this was discussed on a state-by-state basis. Timing of repurposing also matters, for example natural gas pipelines are being used today, they are not available for re-purposing even if we would like to – but maybe we could use the same right of way instead?
Tony - there are a number of issues on how storage will interact. Large formation with closures may be connected by an aquifer. If you start pumping CO2 the pressure will propagate. If someone else wants to use an adjacent structure, how will this impact the injectivity? No one knows how to address this.
Questions arising from the floor included: a discussion on the criteria needed for pipelines transporting hydrogen; right-of-ways; impurities and the trade off of removing impurities verses designing infrastructure to cope with impurities; community engagement and the re-use of wells.
To conclude it was recognised that more experimental data is needed to cover gaps in knowledge of the composition of CO2 and the impacts. Time is now of the essence, each project is unique, there are lots of opportunities and codes and regulations need to keep up so there is broad alignment.
