Scale formation is a very troublesome issue for oiland gas industry, and chemical treatment is a cost effective approach for solving scale formation prevention and control. Monitoring scale inhibitor residual is very critical for inhibitor dosage controlonboth downstream and upstream applications. Currently, there are several major testing methods for scale inhibitor detection down to part per million(ppm)levels, including 1. Inductively coupled plasma (ICP) and wet chemistry method for phosphorous containing inhibitors; 2. Hyamine turbidity method; 3.High performance liquid chromatography (HPLC) for certain types of polymer inhibitors, e.g. sulfonated copolymer inhibitor; 4. Florescence dye tracer, e.g., PTSA and fluorescein; 5. Colorimetric method for polymer residual detection; 6. Time Resolved Florescence (TRF) for both phosphonate and polymer inhibitors; 7. Surface Enhanced Raman Spectroscopy (SERS) for phosphonate inhibitorsmonitoring and differentiation; 8. An assay method for the detection of all scale inhibitors at extremely low concentration 9. Strip Immunoassay technique for tagged polymer inhibitors.This paper summarizes scale inhibitor residual methods based on the testing results with synthetic waters, cooling waters, and produce waters, and presentslaboratory and field testing data under different application conditions, including brine TDS, pH, etc. This paper gives the insight on selecting best-fit scale inhibitor monitoring methods for both downstream and upstreamapplications.

Keywords: Scale Inhibitor, Residual Detection, Methods