FLOW ASSURANCE OF pH STABILIZED WET GAS PIPELINES

摘要

The pH-stabilization method is a cost effective and reliable way to control bottom of linerncorrosion in gas/condensate pipelines where glycol is used as hydrate preventer. Increasing the pH torn6.5-7.5 facilitates the formation of a protective iron carbonate film on the steel surface and reducesrncorrosion of the steel. pH stabilization will also affect top-of-line corrosion, but to a less extent than inrnthe bottom of the line. In order to reduce top-of-the-line corrosion significantly, pH stabilized glycolrnmust be transported from the liquid water/glycol phase in the bottom of the pipeline to the gas phasernin droplets and then hit the wall. The likelihood for this is discussed and it is also discussed how thernpH stabilizer can reduce the detrimental effect of Hac in the gas.rnThe carry-over of formation water will put limits on the use of the pH stabilization technique asrncarbonate scale may form. Scale formation in glycol carrying pipelines is not easy to predict, asrnsolubility data for COrnCO2 and scale forming compounds in glycol solutions are very scarce. Glycolrnaffects scale formation by changing the solubility and the precipitation kinetics, and the solubility ofrnfor instance calcium carbonate is markedly reduced. If the periods with formation water carry-overrninto a pH-stabilized pipeline are short, scale inhibitors can probably be applied without adverse effectsrnon corrosion. Long-term use of scale inhibitors in a pH stabilized pipeline is probably not feasible.