ABSTRACT:

Top-of-the-Line (TOL) corrosion is a significant problem associated with the transportation of wet natural gas in the oil and gas industry. It has the potential to cost the industry millions of dollars every year through the replacement of affected pipelines and lost or deferred production. There is increasing research attention given to the development of continuous chemical treatment inhibitors to mitigate TOL corrosion. Different techniques have been developed; however, volatile corrosion inhibitors (VCIs) hold the most promise. It is anticipated that VCIs may be injected continuously into the produced fluids at the bottom of the line and due to their volatility disperse through the gas phase and ultimately co-condense along with water, organic acids and corrosive gases on the internal pipe wall, thus providing corrosion inhibition. Three generic volatile inhibitor compounds, a primary, a secondary and a tertiary amine have been tested in two different TOL and one bottom of the line (BOL) laboratory corrosion test; a Cooled Finger Probe and a Horizontal Cooled Tube to verify Top-of-the-Line inhibition properties and linear polarization resistance (LPR) measurements using a rotating cylinder electrode (RCE) setup to test their BOL inhibition properties.

INTRODUCTION

Top-of-the-Line (TOL) corrosion in wet gas pipelines has been a severe problem for over half a century in both sweet and sour conditions, resulting in high costs of the replacement of affected subsea pipelines.1, 2 This can be avoided by the use of corrosion resistant alloys, however, inhibited carbon steel pipelines are usually the most cost effective choice for sweet service. There are two main treatment methods: batch and continuous treatment. Continuous chemical treatments like spreading and volatile corrosion inhibitors (VCIs) have the advantage that the chemicals are continuously injected into the water phase at the bottom-of-theline (BOL) during production without loss of productivity.

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