Shell: The Sour Gas Experts

“In the Middle East, Shell’s notable contaminated gas projects include our joint venture with Petroleum Development Oman to develop the Harweel field cluster, while we are also supporting the Kuwait Oil Company in its efforts to unlock very challenging contaminated-gas reserves from Jurassic formations deep underground in Northern Kuwait,” said Andrew Vaughan, Shell vice president for Abu Dhabi, Kuwait and country chairman of Abu Dhabi.

“Last year we were delighted to have been selected by the Abu Dhabi National Oil Company [Adnoc] as their partner to deliver the Bab sour gas development.”

Sour gas is so called because it contains hydrogen sulphide (H2S) which is both corrosive and poisonous. Developing sour gas reservoirs requires special materials and chemical processes to clean the H2S out of the hydrocarbon gas before it can be piped to market. The operating procedures for developing sour gas fields must be rigorous and well designed to ensure personnel safety.

“Shell has developed special technologies for sour gas production and we have over 60 years of experience developing highly sour gas fields. We will be bringing these technologies and experience to the Bab gas development in Abu Dhabi,” said Vaughan.

H2S is highly poisonous but with the right procedures it can be produced safely. It is important production plants are designed, and maintained to minimise any risk of leaks.

“The Bab field is complex both in terms of the sub-surface and the surface facilities. I wouldn’t say it was more complex than other fields Shell has worked on; none of the complexities are new to us. That does not mean to say that the development is not challenging for Shell and that is why we are planning the design of the project very carefully.”

Shell says it is important that detection mechanisms are in place in case a gas leak does occur and it is important that staff are trained for awareness and response to H2S.

“At the end of the day, responsible operation of sour gas projects can mean only one thing: the lowest possible incident rate during the whole life-cycle of the project. Shell recognised this from the early days of our sour gas operations in Canada that date back to the 1950s. We’re happy to be able to look back on decades without a major incident,” said Vaughan.

In a sour gas field it is absolutely essential that the volumes of dangerous gas are constrained, according to Shell, and that if any gas is accidently released, people are protected.

“In order to achieve this, we must maintain asset integrity through prudent design and safe operation. In the rare event of a leak we must be able to respond quickly. The most critical element is the way in which personnel work in sour gas plants,” said Vaughan.

“All Shell exploration and production operations comply with federal, state and provincial regulations, in many cases exceed standards. We believe our practices are among the most comprehensive in the industry. For every project, we develop a thorough ‘safety case’, which is unique for each operation, making sure health, safety, security and environment risks are identified and addressed. It is in this safety case that safety equipment is specified.”

Shell has a vast sour gas portfolio with over 60 years of experience globally. Shell in Canada is the major owner and operator of the Waterton Complex, which produces methane, ethane, propane, butane, condensate and sulphur.

Waterton is one of four different Shell gas complexes in southern Alberta, contributing to a combined overall production average of 8.5mcm/d of natural gas.