As sour gas becomes more and more common in reservoirs around the Middle East, the oil and gas industry is looking to more innovative and safe methods of production and handling.
The Sour Oil and Gas Advanced Technology (SOGAT) conference and exhibition of 2011 drew in global experts on the ever-increasing field of sour gas recovery, handling and processing resulting in a rich exchange of ideas.
The Abu Dhabi event, held at the end of March was sponsored by some of the Middle East’s key energy operators with significant investments in sour gas operations.
Abu Dhabi Gas Development Company, now known as Al Hosn Gas, one of the major sponsors of SOGAT and in charge of developing the massive Shah sour gas field in Abu Dhabi, gave an update on the project particularly in terms of its HSE design and implementation considerations.
US Engineering, Procurement, Construction Management services provider Fluor oversaw the pre-FEED and FEED stages of the Shah Gas Development or SGD. It provided an update on the project which seemed to be on everybody’s mind at the event.
“Considering its size, cost and complexity, the Shah Gas Development programme has really proceeded at a fairly aggressive pace,” said David Schulte, Fluor’s principal process engineer.
“In June 2007 the feasibility studies and pre-FEEDs were completed by Fluor. In February of 2009 Fluor completed the FEED, March 2010, the first EPC package was awarded, this was early works and that went to Al Jaber. In May of 2010 the main EPC packages associated with the main plant were awarded to Saipem, Samsung and Technicas Reunidas.”
“Just last month the drilling started and by third quarter of 2014, the target is to have completed the performance test, so if you look at the time gap between the award of the main packages and when we’re going to achieve provisional acceptance, we’ve only got 52 months so it is an aggressive programme,” he added.
SGD consists of four major elements: The gas gathering system; The Shah processing plant; product pipelines and the Shah sulphur station. The field’s high H2S content – 23% in the well fluid – means that in addition to key HSE design and implementation considerations, it will pose certain unique challenges due to the sheer scope of work to be done.
“This is a billion scf/day (standard cubic feet a day) megaproject, this is not an incremental investment and incremental expansion, it’s an immediate step to a billion scf/day,” explained Schulte.
The remoteness of the location offers up its own set of unique challenges as far as logistics is concerned, he said let alone construction and other related issues.
The four main products expected to be produced from the billion scf/day of feed gas at SGD which lies about 180 kilometres southwest of Abu Dhabi, are sales gas (500 million scf/day); NGL (4,400 tonnes/day); sulphur (9200 tonnes/day) and about 33 000 bpd of condensate.
Issues such as site location, plant layout, prevention detection and control strategies were discussed by Schulte where he said that worst case scenarios such as adverse weather conditions during an H2S leak at the plant were taken into consideration for its design.
Sulphur handling
The SGD project will have a total of four trains – the largest in the world – for the massive Sulphur Recovery Units (SRU) that would process the 1 billion scf/d of sour gas. The SRUs will have a capacity of 2500 tonnes per day.
“Originally the concept was to transport sulphur in liquid form all the way from Shah via hot water jacket pipelines down to Ruwais for granulation and export,” Schulte explained.
“Based on the decision of Abu Dhabi to create a national rail system, the opportunity arose for the project to take advantage of that and utilise that railway to transport sulphur from Shah to Ruwais.
So what we’re doing now is that we actually have shorter sulphur pipelines – only about 11km long – that will take the sulphur from the Shah plant to the nearby sulphur station where the sulphur is granulated, loaded on railcars and sent down to Ruwais for export,” said Schulte.
Petroleum Development Oman update
Sultan al-Naamani is Petroleum Development Oman’s (PDO) senior engineer for its operation readiness and assurance division for sour gas projects. He believes that there is much to be gained from gatherings such as SOGAT as it allows national oil companies such as PDO to learn from industry experts at a level they are able to actively engage in.
“In this SOGAT we have teams from the sour processing and we have a team from sulphur recovery and we have a team visiting an ADNOC facility to share the knowledge to see the plants and talk to the operations guys and project teams on their plants which they have been operating for more than 30-40 years,” he says.
Al-Naamani added that issues pertaining to best practices, planning, integrity and overall safety were of particular interest to attendees of SOGAT.
He said that PDO is carrying out a number of benchmarking exercises with other sour operations and companies in the region such as Saudi Aramco to develop a regionally indigenous best practices approach to dealing with sour gas. He added that PDO also carried out benchmarking with companies in North America, Europe and Russia.
Al-Naamani’s colleauge Salim Ojaily, lead facility engineer, Rabab-Harweel integrated development project, presented a paper on the impact on surface facilities when souring up reservoirs.
Using the example of the Rabab field in the south of Oman, Ojaily discussed how the components of acid gas increase over the life of the field and how that affects the design of surface processing facilities and how PDO arrived at the decision to solve problems associated with this.
He explained how PDO, faced with the issue of disposing of the acid gas, had essentially three options: to inject it in the gas and condensate fields; to inject it in the oil fields; or to split it between the two sets of fields.
“The best option to take that would mitigate all the design issues is to equally share it because if you put it in one of the fields, there’s too much souring in it, we do not want the design to be sub-optimal,” he said.
“You’re trying to minimise the extent of the material that you are selecting, you don’t want to select very stringent materials by making the choice to inject it in one of the fields.
If you have more than one [field] the best choice is to equally split it, and this slows down the build-up of acid gas components, you don’t hit problems very early but you hit them late and in doing that you have ways to mitigate it, you have time to observe it and if it happens, you can make changes,” he went on to say.
Sulphur market update
As sulphur is the main by-product of sour oil and gas production, SOGAT attendees were able to peer into the crystal ball of the global sulphur market over the next decade with a little help from ICIS PentaSul’s market analyst, Fiona Boyd.
She made her presentation at the 1st International Sulphur Management Forum at SOGAT and spoke of how global sulphur production growth in terms of new projects, is increasingly being matched by consumption from the fertiliser and metal production sectors in emerging economies such as China and India.
“What we’re seeing in particularly in North America is a increase in the ability to process bitumen from the oil sands which has a heavier sulphur content and then here in the UAE it’s sour gas which has a heavier sulphur content so that is what’s driving these increases in sulphur production particularly as these new projects come online,” explained Boyd.
“Shah Gas being one of those will produce around 3.5 million tonnes of sulphur a year,” she added.
“In 2013 and 2014 we see a global deficit in the sulphur market, something that’s important to understand is that some production particularly in Canada can’t make its way to the market because of logistical issues – every tonne would have to be trucked because there are no rail connections.”
Boyd said that there is significant growth in the region’s sulphur production with Saudi Arabia exporting almost 3 million tonnes last year and Abu Dhabi behind it at 1.9 million tonnes, adding that they were both major global players serving China, Morocco and India.
She described how drastically the sulphur market has changed in terms of pricing: “Gone are the days where sulphur just hovers along at 50 bucks, it’s a more cyclical and volatile market now, that started in mid 2008 where we saw the market go up and crash and that’s just based on overall economic conditions.”
Boyd predicted a tight supply-demand balance at least till 2020 until new supplies comes on the market, she attributed this to a weaking of demand after the global downturn in 2009.
“Phosphate producers operated at very low capacity and then all of a sudden they needed all this sulphur to keep up with demand and it’s just not there because the sulphur producers have not been running at capacity either,” she explained.
Statoil’s compact Co2 capture plant
Norway’s Statoil made a last-minute appearance at SOGAT with Torbjørn Fiveland, its principal researcher for Process Midstream/Downstream operations, revealing details of the company’s compact CO2 capture plant which is currently in a proof-of-concept test stage.
He explained how current CO2 capture plant equipment is large and expensive to operate.
“We aim to reduce CAPEX by at least 50% and OPEX by at least 30-50%,” he said describing his concept. “By reducing the costs it is possible to capture CO2 and of course make money on EOR to increase the pressure in oil fields, especially here in the Middle East where a lot of oilfields are suitable for CO2 injection.”
Fiveland said that the compact CO2 capture plant which is said to have a much smaller footprint compared to the conventional technology available, was being tested to capture flue gas.
“Pressure [in natural gas] is high, meaning the gas volume is significantly lower, then it’s possible to use rotating equipment to capture CO2 and by doing that we assume that we will reduce CAPEX and OPEX significantly,” he stated.
Fiveland hinted at possible pilot ventures with Masdar and Adnoc for the technology which can be used both onshore and offshore.
“The logical thing is to start with a pilot, that could be a proof-of-concept which we could build in Norway or we could pilot it in Abu Dhabi,” he explained.
