Sour gas - A history of expertise - Total.com

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Processing of hydrocarbons from the Lacq field
raw gas
desulfurization sulfur recovery unit
sweet
gas
Condensate
removal
lacq crude oil stabilization
thiochemicals
ethane
steam cracker
sulfur
thio
products
commercial gas
lpg
(butane, propane)
Ethylene
light hydrocarbons
condensates
petroleum products
the drilling assembly and plug the well. When the drill string was pulled
out, the engineers discovered an unusual phenomenon – the gas had
altered the molecular composition of the steel and caused cracking in
all the welded parts.
sUlfide Corrosion CrACKinG
The explanation for this phenomenon lies in the composition of sour
gas. Containing 10% carbon dioxide (CO2) and 16% hydrogen sulfide
(H2S), as in the case of Lacq, the gas causes “sulfide corrosion
cracking.” No one at the time knew how to produce sour gas with very
high levels of sulfur, and experts considered the Lacq discovery a
“write-off.” That was no deterrent for Total. The Group set out fully
determined to develop the field, which promised to be a major discovery
(over 240 billion cubic meters).
Two wells were drilled to appraise the size of the reservoir – one
1,500 m north of the initial well, the other 1,500 m to the south.
Both encountered gas, as recorded in 1953. A major research effort
then got under way to define the materials and processes needed
to develop the gas. In 1955, after two years of work, the Pompey
steelworks presented a type of steel that was resistant to H2S.
1. Aerial view of the Lacq complex,
France.
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2. Total has developed a control
system that adjusts the activity
of reagents in real time to guarantee
specified composition of the
treated gas.