Scale inhibitors are used extensively in the oil and gas industry to provide the level of flow assurance required to maximise safe and economic hydrocarbon production. For both continuous and scale squeeze treatments, residual inhibitor concentrations need to be verified on a continual basis to assure the field operator that the implemented scale management program remains effective. To date, the analytical work required to verify residual inhibitor levels of the majority of scale inhibitor chemistries needs to be carried out onshore in a suitably equipped analytical laboratory. Often the time delay from sample collection to reporting of analytical results introduces a significant level of uncertainty with regard to effective scale control which, if removed, would substantially improve the production assurance and safety of the facility operations.
The Residual Monitoring and Analysis system is a point-of-use monitoring platform designed to measure the residual concentration of polymeric scale inhibitors with average molecular weight less than 10 000 Da in produced water, providing a timely and accurate residual scale inhibitor concentration to the facility operator. The analysis procedure can be carried out at the production location where the sample is taken, with the result obtained and recorded within 30minutes or less. The analysis method is unaffected by either the presence of other production chemicals or by the variation in typical North Sea produced water composition.
The measurement system utilises the Aqsens aqueous liquid fingerprinting technology platform (Hänninen et al. 2013) and can be designed to work with a wide range of scale inhibitor chemistries; a specific tag/label is not necessary. Unlike other systems, the analytical method is not based on immunoassay detection technology that requires modification of the scale inhibitor formulation to include tagged polymer-specific antibodies. We have deliberately reverse engineered this for a range of current scale inhibitor products to provide direct field analysis to customers on either continuous or scale squeeze application programs.
The system derives its sensitivity by combining time-resolved fluorescence with carefully optimised chemistries to quantify the product for scale inhibition levels. Performance results from laboratory testing and coreflood experiments will be presented.