Schlumberger

Case Study: Innovative Dispersing Agent Mitigates Wax Buildup in Platform Heat Exchanger, Condensate Export Line

Continuous application of PI-7393 paraffin solvent ensures ongoing operations without interruption, North Sea

Challenge: Mitigate wax buildup caused by precipitation in a platform heat exchanger and condensate export pipeline.

Solution: Deploy PI-7393 paraffin solvent to replace the previous product and deter wax buildup in the heat exchanger and pipeline.

Result: Prevented wax buildup and enabled continuous, uninterrupted operations.

Wax buildup in platform heat exchanger, export line

A platform offshore Norway gathers and stabilizes condensate production from the Heimdal, Huldra, Skirne/Byggve, and Vale fields for transport through a 72-mi [116-km] 8-in export pipeline to the Brae Alpha platform in the UK sector of the North Sea. Increasingly waxy condensate from the Vale field led to the need for a comprehensive wax mitigation strategy. Without previous wax inhibition treatment or pigging, a 6-in foam pig had gotten stuck and caused a shutdown. M-I SWACO, a Schlumberger company, developed the PI-7237 paraffin solvent to overcome the challenge.

Two years after the PI-7237 solvent was deployed, the fluid composition of the well had changed, and the solvent was no longer the optimal choice for the Heimdal export condensate. High temperatures prevented precipitation buildup in the Vale subsea line, but precipitation occurred in the Brae platform’s heat exchanger and export pipeline when Vale condensate was diluted by fluids at the platform.

Cost-effective dispersion with PI-7393 solvent

Comprehensive testing identified the PI-7393 paraffin solvent as the most cost-effective wax inhibition solution for the Vale condensate. Continuous application of the solvent controlled wax precipitation in the heat exchangers and the Brae pipeline.

Elimination of wax deposition

The PI-7393 solvent is now used as the primary inhibition chemical to reduce the amount of wax deposited in the export heat exchangers, and the Brae pipeline is continuously pigged. The PI-7393 solvent reduces the amount of wax precipitated, particularly in the heat exchangers, where the export condensate temperature was reduced from 356 degF [180 degC] to 95 degF [35 degC]. Today, the Heimdal field continues to produce without any major wax issues.


Download: Case Study: Innovative Dispersing Agent Mitigates Wax Buildup in Platform Heat Exchanger, Condensate Export Line (0.10 MB PDF)

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