An In-depth Look into Internal Corrosion at Well Site Separation Skid Water Outlet Piping and How to Prevent It

Abstract This paper examines the internal corrosion mechanisms observed during both the initial and steady-state production phases of a well separation skid water outlet piping system. The corrosion processes were influenced by a range of factors including acid gases, solid particles such as sand, flow variations, water chemistry, bacterial activity and the operational configuration of the piping. Extensive testing was carried out, including chemical analysis, hardness testing, microscopy, X-ray diffraction and scanning electron microscopy coupled with energy dispersive spectroscopy. Additional analyses of water and solids, bacterial counts by serial dilution and qPCR were carried out. The primary corrosion mechanism was identified as CO2 corrosion, with potential exacerbation by MIC and UDC. The paper outlines mitigation and control strategies, including chemical treatments with corrosion inhibitors and biocides, physical cleaning by flushing, installation of secondary sand separators, and redesign of the piping layout. In addition, corrosion monitoring and non-destructive techniques to assess metal loss and anomaly growth are used to verify the effectiveness of control and mitigation barriers, such as the use of coupons, X-rays and monitoring of iron, manganese and bacterial counts. Implementation of these strategies will effectively mitigate internal corrosion and prevent LOPC, thereby ensuring the integrity of the asset.