Marginal options for small pools

The UK North Sea’s extensive pile of marginal fields offer an attractive prize, if they can be economically unlocked. Steve Hamlen reports.

UK marginal pools visualized. Image from the Oil & Gas Technology Centre.

As oil and gas provinces mature and the largest fields have already been developed, operators look to exploit the remaining smaller reserves. This often involves the use of new technology and more cost-effective solutions. This is certainly the case for the UK North Sea, as the region is looking to “small pools” – marginal fields with less than 50 MMboe.

Chris Pearson, Small Pools Solution Centre Manager for the Oil & Gas Technology Centre (OGTC), is tasked with finding ways to develop them.

There are an estimated 600 marginal fields around the world, according to Pearson’s presentation this March, who said this presents a great opportunity to export technology and expertise from the North Sea, because the majority of these fields are located offshore the UK.

There are more than 350 undeveloped discoveries on the UK Continental Shelf (UKCS) and 160 are either in relinquished blocks or areas that have yet to be re-licensed.

Together these represent 3.4 billion boe of technically recoverable reserves that offer the UK industry some US $228 billion (£175 billion) in potential revenues. So, small pools could be big business and the supply chain could benefit from a push towards bringing some of them onstream.

“It is therefore entirely logical that the boost to the supply chain would almost be instantaneous as industry sanctions their investment in the development of these fields. It is with this in mind that the OGTC is focused on both near-term development ‘wins’ and in parallel fundamental research that can transform how we provide energy across the UK,” Pearson told OE.

“The OGTC has combined funding of $234.5 million (£180 million) from both the Scottish and UK governments. Our obligation is to match-fund this with industry contribution envisaged as ‘benefit in kind’ by allowing access and support to oil and gas infrastructure, application of expert knowledge and access to assets that will assist us in achieving our goal.”

Around 70% of these marginal fields hold less than 10 MMboe. In addition to their small reserve volumes, other challenges exist, such as, low energy reservoirs, difficult fields, fluid commingling, differential pressure and gas disposal.

The best solutions on offer to operators come from adopting a “cluster and collaborate” approach, Pearson notes, adding that mapping of these small pools was completed in 2016 and cluster analysis has revealed promising areas of development.

The Moray Firth has 43 discoveries in 11 potential clusters, while the Central North Sea (CNS) has 64 discoveries in 18 potential clusters.

“The majority of the marginal fields are in the CNS. However, in order to achieve the objectives of the Wood Report, the UK needs to develop and utilize existing infrastructure across the UKCS,” he says.

Infrastructure access

Pearson

Access to existing infrastructure offers marginal fields promising development options. The distance from these facilities will help dictate the best development solution, Pearson says.

The OGTC estimates that around 30 discoveries are potentially suitable for extended reach drilling (ERD), at between 0-5km from infrastructure, while 200 finds are suitable for subsea tiebacks (less than 20km), and around a further 120 discoveries would require standalone cluster developments (more than 25-30km away, sometimes less).

The use of existing infrastructure would help to extend the life of the host facilities, which is within the remit of the UK’s MER (Maximizing Economic Recovery) strategy.

Indeed, some of the undeveloped discoveries are being assessed for suitability for ERD by the UK’s regulator, the Oil and Gas Authority (OGA),” Pearson says.

“Other fields will benefit from a reduction in the entire lifecycle cost. This does include how we design, build and install systems for a lower cost that we currently achieve. We are designing the next stage of those projects to find a suitable field trial to demonstrate where the utilization of those technologies would be appropriate.”

With regard to potential standalone projects, Pearson adds: “There is a varied set of solutions, such as remotely operated unmanned and light-manned systems. There is no single approach that can deal with the entire range of reservoirs properties currently undeveloped, so we are supporting a number of concepts to test feasibility, alignment with our objectives of MER, plus the economic value returned from supporting a reduction in life cycle costs for the developments.”

Licensing options

The OGA is putting a strong focus on mature areas and relinquished blocks in the upcoming 30th Licensing Round. The OGA will also release data packages on the aforementioned 160 unlicensed discoveries, while also looking at models “from cooperation to unitization” in order to “facilitate joint area development plans,” the OGA says.

Alignment of license terms is also on the cards, such as expiry and timing commitments, “to induce synergies for exploration and development campaigns.”

Earlier this month, the OGA unveiled measures designed to make data openly available and stimulate interest in the UKCS ahead of the 30th Round.

“Data and technology are key to unlocking as many of these undeveloped discoveries as possible,” says Gunther Newcombe, operations director, OGA. “That’s why we’re making this data openly available; to provide useful insights into each discovery and the potential these may hold. We want to see swift deployment of technology to help unlock many of these discoveries.”

New technology

The use of new and immature technology will be critical to unlocking the potential of marginal fields on the UKCS, playing a major role in reducing costs of and extending the reach of small pools projects, Pearson says.

In terms of cluster technology, the OGTC is looking at mechanical hot taps, mechanically connected pipelines and multi-use pipelines. For standalone options, the OGTC is mulling “tiebacks of the future” and not-normally-manned facilities, which are designed for disassembly.

The search for new technology relies heavily on communication and the exchange of knowledge, Pearson says.

“Collaboration is part of our DNA in the OGTC. We simply could not achieve our aims without building and nurturing collaborative behaviors across all of our activities. It can always be improved and is always open to challenge,” he says.

An OGTC call for proposals for ideas to unlock small pools was launched this May, with some £1 million funding available to take ideas forward.

The OGTC is also looking at standardizing the subsea development lifecycle approach to support rapid engineering and delivery of a project; full interconnectivity between modular subsea components; the re-use of subsea equipment from one field to another; interoperability with present and future systems; and the use of a range of key supplier specific subsea components. Other, more conceptual ideas include gas to power, at site, potentially tying in with offshore wind grids, filling in for spare capacity.

Design and efficiency

Industry body Oil & Gas UK is also pushing operators to adopt leaner designs using industry standardization for marginal developments.

Indeed, since the oil price crash of mid-2014, many UK operators and contractors have realized that collaboration is essential to driving down project costs, while development designs must be optimized to make them economically viable. During the March presentation, Oil & Gas UK cited four recent case studies when operators looked for more efficient designs and streamlined solutions.

The first saw an FPSO riser system cost $10.1 million (£7.75 million), a 25% cost saving; the second achieved a saving of 18%, with a subsea pipeline tieback costing US$16.9 million (£13 million); a third saw a subsea manifold and bundle costing $33.7 million (£26 million), a 15% saving; while the fourth, another subsea tieback cost $18.8 million (£14.5 million), a 28% saving.