As the world’s population inexorably increases and economies emerge, one thing is as inevitable as death and taxes: energy demands are going to keep going up.
A recent ExxonMobil study revealed global natural gas demand would grow by 40% in little more than 20 years and the region that will rely most upon this particular form of energy to meet its requirements? The Middle East.
The global grab for gas has inevitably led to the pursuit of innovative techniques to make it more accessible and plentiful for domestic and industrial users alike. The proliferation of liquefied natural gas projects is one example and the commitment to ambitious sour gas field development projects, with many located within the Arabian Gulf, is another.
But so much within the energy value chain circles back to the price of Brent crude. The processes involved in treating, or sweetening, sour gas and removing the highly toxic hydrogen sulphide gas (H2S) and also the carbon dioxide (CO2) found within it are expensive.
Health and safety
The fact sour gas contains such a potentially dangerous component necessitates that health, safety and environmental standards must be maintained whether oil prices are on a peak or in a trough.
Dr Nick Coles, director, Dome Exhibitions, the organisers of the SOGAT conference and exhibition, believes changing trends and needs mean that operators have to look beyond issues such as the oil price.
“In the past, a highly sour resource might have been considered unattractive for development relative to other assets, today operators are developing fields containing as much as 30% H2S as witnessed by the success of ADNOC’s Shah project.
“The interest in these resources reflects several intersecting trends, including the diminishing availability of easy-to-produce conventional oil resources. These sour petroleum resources, in fact, have historically characterised this region and international oil and gas companies must be ready to face the challenges of highly sour production in exchange for the opportunity to operate in these rich oil provinces.”
Abdallah Al Zyod, DMDS technical sales engineer at French chemicals firm Arkema says margins for refineries are less directly impacted by the oil price and so, with the current improvement in the market, operators may now look to debottleneck sulphur recovery units (SRU) at existing plants or install new SRUs to meet the expected increase in sour gas production.
Al Zyod adds that while the low natural gas prices over the past two years have “given advantage to sweet natural gas production versus sour gas production”, operators are not basing future investment decisions on current prices and consequently “very large sour gas projects” will be coming on stream in the coming years.
Arguably the key procedure in the sweetening of sour gas takes place in the Claus process, where elemental sulphur is ultimately recovered from the H2S.
Over many years, this versatile by-product was ignored and wasted, akin to flare gas at an oilfield, but, in the era of ever-greater efficiencies and the widely adopted philosophy of squeezing every cent out of every barrel, this is no longer the case.
Alessandro Buonomini, sulphur recovery process group leader at KT Kinetics Technology, reveals attitudes within the industry have changed. “Sulphur is a key component used in several applications that have an impact on our daily life, and so this by-product has come back into the limelight. The increased quantities now produced by oil and gas processes have forced the industry to think how to value this product.
“In the past, the sulphur was stored in blocks, mountains where it was thrown without quality requirement or any idea as to its future use or application.”
Buonomini says increasing demand from emerging economies for sulphur, which has multiple uses including in fertilisers and as a fungicide, has heightened its importance and status within the industry.
But could an increasing demand for sulphur mitigate the high costs of sour gas production and even help to reassert the need for future projects? Buonomini is not convinced there is a direct correlation.
“The sulphur market is really a regional market. Having a market for the produced sulphur for sure may help sour gas exploitation – more significantly if the market is local. However, we deem that sour gas projects are gaining importance not only for the expanded sulphur market but also due to the increased attention to aspects like ambient air quality.”
Indeed, with increasingly stringent environmental regulations coming into force, pollutant removal is an increasingly persuasive argument for sour gas projects.
Technological breakthroughs
But without doubt, technological breakthroughs and the consequential cost efficiencies, as with all oil and gas processes, remain a major factor in the future allure of sour gas extraction projects.
Ganank Srivastava, consulting engineer – Asia & Australia, Bryan Research & Engineering, feels process simulation is playing a significant part in the effective scrutiny of plants.
“From a global environmental point of view, process simulation gives engineers a robust platform to properly design and model processes that aid the removal of harmful contaminants such as CO2 and H2S from their hydrocarbon mix.
“Process simulation simplifies the task of evaluating an existing process unit configuration and subsequently investigating a wide variety of potential improvements at the same time. Therefore, debottlenecking your plants by pinpointing those exact key performance indicators that need modification has become much easier. It also gives engineers the opportunity to simulate possible process hazards and determine what specifications need to be immediately changed to close those gaps.”
The development of affordable, yet less corrosive, materials and parts would also help with the bottom line. Dr Coles of Dome Exhibitions explains that while it may be possible to use cheaper materials in sweet gas wells, sour wells require top-of-the-range corrosion resistant alloys to handle the extreme environments as well as the intense pressure.
“When selecting materials for use in a sour gas situation, the engineer will have to consider a wide range of factors. This includes the mechanical properties of the alloy and its resistance to pitting and crevice corrosion, chloride stress corrosion cracking, sulphide stress corrosion cracking and general corrosion.
“Alloys are often age-hardened, especially for offshore applications. This is because of the extra strength that the age-hardening process imparts on to a material and the need to withstand high pressure/high temperature situations experienced operationally.”
Sulphur is not the only by-product of sour gas exploitation. CO2 is also generated and theoretically this offers potential for use in enhanced oil recovery processes providing another benefit to sour gas exploitation.
Buonomini feels sour gas offers further possibilities. “Other by-products are produced in the sour gas processes. We guess the industry, together with engineering companies, should study the possibility to diversify and intensify the use of such by-products towards not only the minimisation of the operational expenditure of sour gas processes but also towards the development of new and alternative processes.”
