Beyond the Limitations of API RP-14E Erosional Velocity -A Field Study for Gas Condensate Wells

Abstract

Fluid velocity has the potential to cause severe erosion damage to oil & gas production infrastructure. In order to avoid or alleviate damage due to erosion, the American Petroleum Institute Recommended Practice (API RP) 14E recommends a threshold fluid velocity for production tubing and pipelines. However, field and laboratory data have proven that the applied empirical constants, known as C-factors, within the formula are not valid for all conditions. In many cases the calculated API RP 14E erosional velocity is significantly underestimated or overestimated due to insufficient consideration of fluid characteristics. In addition, accurate field data on erosional velocity can assist proper pipe sizing calculations for prospective oilfield projects. Oversizing of tubing unnecessarily increases construction costs whilst underestimating required size of tubulars can lead to catastrophic erosion/corrosion failures. In this study new values for erosional velocity constants, beyond those suggested by API RP 14E, are proposed based on experimental data achieved from sidestream pilot test units. The experimental pilot test units were installed on four different gas condensate production fields in the south of Iran. Electrical Resistance (ER) probes were employed to gather online erosion-corrosion data from the pilot units, each of which was in service for about nine months. The results showed that higher C-factors can be safely applied for these gas condensate fields in comparison with those recommended by API RP 14E. Furthermore, it was revealed that pilot test units exposed to a higher Condensate Gas Ratio (CGR) experienced a greater rate of erosion.