Processing sour gas requires special handling and infrastructure, and is costly and dangerous, as it is highly corrosive, flammable and explosive. These difficulties are the prime reasons for many of these resources not being extracted for many years after the initial discoveries were made.
The last decade, however, has witnessed IOCs with the resources, expertise and technology to handle these scenarios successfully developing many major sour gas projects around the world, including in the Middle East.
The advantages of sour gas development – enhancing gas supply, aiding enhanced oil recovery (EOR) operations, and catalysing industry growth – are major attractions for international energy companies, which are investing heavily in the segment. In return, they are bringing innovative technologies to the region’s hydrocarbon sector.
Operators must apply the sophisticated technologies available, and invest substantially in R&D to develop new and innovative technologies, in order to obtain maximum commercial value from the sour gas projects. IOCs, facing health and safety as well as environmental challenges, are demanding safety management systems and risk mitigation plans to be integral parts of these projects.
Most of the sour gas locations in the Middle East involve a hostile natural environment as a result of the extreme desert heat. This reinforces the need for the highest industry standards in quality for all elements involved with the sour gas projects in the region.
Key challenges related to sour gas processing in the Middle East include very high levels of H2S and CO2, as well as the presence of contaminants such as organic sulphur and BTEX (benzene, toluene, ethylbenzene and xylenes) hydrocarbons. Additionally, fields that do not contain significant liquids (condensate and/or oil) can face challenges related to elemental sulphur precipitation and subsequent plugging in wellheads, gas gathering systems and processing facilities.
Giving an insight into the Middle East sour gas sector, Angie Slavens, managing director, UniverSUL Consulting, remarked: “Many of the technologies used in the Middle East to address these challenges are also employed elsewhere around the world, but the mega-scale of the Middle Eastern facilities makes them unique. Having said that, every gas plant is different and requires a tailor-made approach for its specific composition.”
With the current low oil prices, technologies that can achieve superior technical performance while also minimising cost (CapEx and OpEx) are of the most interest. Some examples include hybrid solvents and integrated acid gas removal/tail gas treating designs.
“BTEX has been historically dealt with in the region by maximising H2S content in acid gas, air and acid gas preheat and/or natural gas co-firing. However, some operators are considering the possibility of oxygen enrichment to achieve adequate BTEX destruction temperature, while also de-bottlenecking existing sulphur recovery unit (SRU) trains,” Slavens continued.
Opportunities for technology suppliers
Sour gas compositions in the Middle East are often complex and challenging, presenting opportunities for technology suppliers that offer clever alternatives for processing at the lowest cost.
“Technology suppliers that have access to a portfolio of technologies to address many of the unit operations in the facility have an advantage due to their ability to develop integration and optimisation schemes between various operating units,” Slavens said.
The Middle East is a region where experience and a proven track record with similar-sized facilities are critical. Thus, novel or first-of-a-kind technologies are rarely employed. Technology suppliers must often provide adequate commercial references from plants that are of a similar size and complexity.
“We have extensive experience in the many treating processes available, noting that no single process is ideal for all applications. We believe the selection of the right tools is crucial. These tools could be a ‘right’ technology, a ‘right’ solvent, a ‘right’ simulator, all critical and mutually inclusive to proper economic design, with low energy consumption to reduce operating and capital costs,” said Krishnaswamy Iyer, director – UAE, Egypt, Iraq and Qatar, WorleyParsons. He added: “The selection of the appropriate chemical, physical or hybrid solvent technology, together with recognition of synergies with the downstream sulphur recovery process, allows an integrated approach to the removal and sulphur recovery of sour gas processing. Final selection is ultimately based on process economics, reliability, versatility and environmental constraints.”
There are many elements that increase the cost of exploiting sour gas reserves. The most important of which are that its contaminants make it very poisonous, creating health and safety issues, and that it is highly corrosive to iron, causing sulphide stress-cracking in the flow lines and production equipment. As a result, there are major complexities in drilling, completion, engineering, handling and storage, and the environmental implications are enormous.
Commercial feasibility
According to the World Bank, the population of the Middle Eastern countries grew by approximately 60% from 1990 to 2010, versus a total world growth rate of about half this figure. Two of the countries in the region that grew the most during this period were the UAE and Qatar, each at around 300%.
Slavens stated: “The main driver for development of sour gas projects in the Middle East is a desire for national energy security to meet the growing demand, coupled with a trend toward switching from heavy fuels to cleaner natural gas for power generation.
“Near-term projections show similar population growth rates for the Middle Eastern countries and, therefore, sour gas demand is expected to continue to increase during the foreseeable future,” she continued.
Describing the dynamics of sour gas processing in the UAE, Iyer said. “The development of the UAE’s ultra-sour gas fields brings many significant challenges, particularly as the levels of H2S and CO2 are considerably higher than in many other gas deposits globally. The extraction process requires specialised design and enhanced infrastructure to manage the corrosive and toxic by-products that the extraction process creates.”
“For example, the development of the Bab field, one of the largest non-associated gas fields in the UAE, will require a specialised and integrated approach to bring together the many different technical and operational solutions to resolve the corrosive nature of the development,” he continued, adding that, along with these technical issues, the other challenge the development of these ultra-sour fields creates is the considerable increase in costs to deliver these projects.
Current sour gas production in the UAE is in the range of 7bn standard cubic feet per day (bcf/d). For the country, sour gas projects are important for the uninterrupted availability of natural gas as feedstock in power generation and industries. As demand for gas in the UAE will continue to grow in the future, there will be a need for further sour gas projects. The country has dealt with some of the most complex sour gas fields in existence and has plans for the development of even more challenging fields in the future.
Since low-cost energy sources are running out, energy producers around the world are making more determined endeavours to ensure the commercial viability of more complex and harder-to-reach hydrocarbon reserves. The economics of sour gas projects are determined by the ongoing technological advances, rising demand for gas, and the global price for the hydrocarbon. For the companies tackling sour gas, the Middle East offers enormous potential.
