Clariant Oil Services Treats Gas Flowlines in HP HT and H2S CO2 Conditions
- Exemplary corrosion protection begetting maximum lifetime of topsides process, including flowlines
- Highest operating standards in regards to health, safety and integrity
Background
A major international oil company operates a gas / condensate field in the central North Sea. The field was experiencing high pressure and high temperature (HP/HT) conditions, with the produced fluids containing appreciable concentrations of carbon dioxide (CO2) and hydrogen sulfide (H2S).
Due to the corrosive nature of the fluids combined with HP/HT conditions, all downhole equipment was completed in a Corrosion Resistant Alloy (CRA). For practical considerations, however, the topsides processing facilities – including the production flowlines – were constructed from carbon steel so the deployment of a corrosion inhibitor was required at the Christmas tree to mitigate for internal corrosion.
In order to achieve the best possible corrosion inhibition performance, the operator carried out a ‘Best-in-Class’ product screening process at an independent laboratory, to ensure that the best available chemical technology would be selected for the application.
The invitation to submit the best technical product was sent to all major, internationally-known chemical vendors, indicating the following typical production and process characteristics:
| Flowline Pressure | Up to 90 barg |
| Flowline Temperature | Up to 123°C |
| Production Rate |
Gas 0.4 x 106 Stm3/day Condensate 3,180 m3/day Water 2,120 m3/day |
| Chloride | Up to 241,000 mg/l |
| Fluid Velocity | Up to 2 m/s |
| CO2 Conc. | Up to 6 mol% |
| H2S Conc. | Up to 50 ppm |
Clariant Oil Services Solutions and Value Delivered
Following an extensive product development process, Clariant Oil Services’ technical experts custom-designed the corrosion inhibitor CORRTREAT 760 to meet all of the operator’s requirements. The operator’s independent evaluations rated CORRTREAT 760 as the best performing product, and so introduced it to the field in 2000. CORRTREAT 760 has been continuously deployed since, and the operator’s corrosion monitoring program (encompassing in-situ corrosion coupons and regular NDT wall-thickness measurements) confirms that CORRTREAT 760 has maintained excellent corrosion control of the topsides facilities.
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