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Cheers! John Downs presenting the benefits of cesium formate brine at the Asia Pacific Oil & Gas Exploration & Production Conference, Beijing in 2008.
“We have tested a particularly heavy salt, cesium formate, which has excellent water solubility and yields a clear, solids-free brine with an SG of 2.30.”
So states a monthly research summary written by John Downs for Shell Research in January 1991. John had found the solution to Shell’s brief to design a high-density drilling fluid that would enable successful drilling and completion of deep slim-hole wells. It was the beginning of the final part of the ‘formate brine trilogy’ – sodium, potassium and cesium – which created a revolutionary new brine system for the oil and gas industry. As John says: “It looked like I had the basis for a clear barite-free brine that could be deployed as high-performance drilling and completion fluid across a wide density spectrum.”
John has dedicated the best part of his life to developing and championing formate brines – in particular cesium and potassium – for the oil and gas industry. Finally, he is closing the curtain on a career spanning five decades, which is a good time for us in Sinomine Specialty Fluids to look back and acknowledge John’s unique contribution to the industry.
A brine is born
Upon leaving Bath University with a BSc degree in Applied Biology, John joined Shell Research in 1973 as a fermentation technologist, focusing on growing polymers in clear brines. As part of this work, he and his colleagues established that potassium formate is extremely soluble in water and can make novel brines with densities up to 1.60 g/cm3 (13.4 lb/gal). Further research showed that their unique properties help protect biopolymers from thermal degradation.
Wanted – high-density cesium formate brine
In 1990, John was assigned to Shell’s E&P Research and Development Laboratory in Rijswijk, Netherlands and was tasked with designing a drilling fluid for deep slim-hole wells. John noted that the performance criteria for the drilling fluid were a close match for formate brine. However, there was a catch. The maximum fluid density provided by potassium formate was short of the maximum density of 2.30 g/cm3 (19.2 lb/gal) required for slim-hole well constructions in deep high-pressure reservoirs. In 1990, John conducted solubility tests and discovered that dissolving cesium formate in water produced a brine that met the required density specification.
The problem was finding a company that could make high-density formate brines in the kilotonne quantities needed for drilling and completion applications. In the early 1990s, there wasn’t even a dedicated producer of potassium formate brine, let alone cesium formate. The latter was only manufactured in very small quantities mainly for laboratory use and had never been considered for oilfield applications. The solution to Shell’s brief to find a successful drilling and completion fluid for deep slim-hole wells, which looked so promising in the testing phase, seemed logistically impractical. In the early 1990s, no company was willing to invest in large-scale production. “When I asked for a quote for hundreds of tonnes of cesium formate brine, only to receive a price of US$ 50 per gram – there are a million grams in a tonne – it seemed an impossible task,” muses John.
The early years – John Downs at Shell’s E&P Research and Development Laboratory, Rijswijk, Netherlands in 1993.
“I visited Cabot Corporation in the USA and Chemetall in Germany – both supplied cesium formate in small kilogram quantities – and begged them to manufacture an initial 500 MT of SG 2.20 cesium formate brine for Shell’s field trials, but neither appeared interested,” continues John.
The absence of a potassium formate producer was remedied in 1994 when Norsk Hydro in Norway began large-scale production of 75% potassium formate brine, ensuring supply of formate brine up to a density of 1.60 g/cm3. However, the challenge of sourcing cesium formate remained unresolved.
In 1993, John was assigned to different R&D projects and others took over the original assignment. “My involvement in formate brines for the next two years was restricted to supporting Shell’s first formate brine trials in the Draugen field offshore Norway and in the Netherlands’ Berkel field,” explains John. “Working with Professor Eric van Oort, my focus moved to water-based shale drilling fluids. Together, we developed the TAME shale drilling fluids that later became very popular.”
The first formate brine company
In 1994, John returned to Shell International Chemicals in London and to selling oilfield chemicals. Less than a year later, John received a job offer: “I was asked to help set up and manage Forbrico Ltd. – a proposed new joint venture between Norsk Hydro and Great Lakes Chemical Corporation for producing and supplying formate brines to the oil industry. Norsk Hydro was to supply potassium formate and OSCA, Great Lakes’ subsidiary, would look after brine sales and field servicing”. John accepted and the first dedicated formate brines company was born.
“Unfortunately, the joint venture only lasted three years”, says John. However, it did provide a platform for John to travel the world promoting formate brines to the oil and gas industry – “missionary work” as he describes it.
The most important ‘sale’
Perhaps John’s most important conversion was Sam Bodman, Cabot’s chairman. Although Cabot declined to supply cesium formate brine to Forbrico Ltd., he was convinced of cesium formate’s potential. His resulting decision to build a cesium formate production plant and establish a cesium formate service company called Cabot Specialty Fluids, now Sinomine Specialty Fluids, was portentous. The plant was built at Lake Bernic in Manitoba, Canada, through Cabot’s （now Sinomine’s）subsidiary the Tantalum Mining Company (TANCO) to take advantage of the gigantic reserves of pollucite ore – the rock cesium is derived from – buried beneath the lake.
John joins Cabot
In 2004, John moved to Cabot Specialty Fluids. He says: “I worked as marketing manager, but also looked after the Middle East, India, Pakistan and Africa, travelling through these regions giving sales presentations and attending countless conferences and exhibitions. Saudi Aramco, Kuwait Oil Company, BP in Egypt and OMV in Pakistan all became customers. In 2012, John stepped back from the business and took early retirement for health reasons.
The pull of formates is too strong
However, retirement didn’t quite take for John. A year or so later John set up his own consultancy, Formate Brine Ltd., offering technical and strategic advice on formate brines and their use in the oilfield. His first client, Addcon, handled the potassium formate business previously belonging to Hydro Formates. Further assignments followed from various clients, including Sinomine, right up until his retirement earlier in 2025 at the age of 74.
John leaves his mark
John’s legacy is a field-proven high-density brine – cesium formate – that complements sodium and potassium formate to complete a range of environmentally friendly, high-performance drilling and completion fluids with densities up to 2.30 g/cm3 (19.2 lb/gal). These brines have been used consistently for over 25 years offshore UK and Norway, and around the world from Kazakhstan to the Gulf of Mexico and from Hungary to India. They’ve replaced halide brines and barite-weighted oil-based fluids to reduce well construction time, maximise hydrocarbon extraction and reduce environmental impact, particularly in challenging fields.
Keeping the home fires burning
John is particularly proud of what this has meant to his native UK: “By encouraging use of cesium formate in gas well constructions, I have inadvertently had some impact on the energy security of my homeland. The vast majority of the natural gas used in the UK comes from domestic production or is imported from Norway. Since 1999, many of the deeper North Sea gas wells providing this vital energy source have been drilled and completed using cesium/potassium formate. For example, the Kvitebjørn field alone has delivered 100 bcm of gas to the UK, while gas from Martin Linge is piped directly to the British mainland. In fact, Equinor stated at the time that Martin Linge had delivered world-class production efficiency for a new field in the start-up phase.1 Both Kvitebjørn and Martin Linge have been developed using cesium and potassium formate fluids.”
All journeys end
As John retires, he leaves the formate brine market in a very healthy state, with more operators using these special fluids than ever. Reacting to Sinomine’s recent investment in new facilities in Aberdeen, including a larger, well-equipped laboratory, John says: “It is wonderful to see that the in-house expertise within Sinomine is being maintained and further developed, as the service provided with the product is essential for its success. It has been a wonderful journey, working for so many years with so many passionate professionals. My thanks to all I’ve worked with for making this journey so interesting.”
Siv Howard, R&D Manager, speaks on behalf of the whole team in Sinomine and says: “We thank John sincerely for laying the foundations of the business we all love so much and for being such an inspiring and enthusiastic colleague over so many years. We wish him a long, happy and fulfilling retirement.”
