Scale inhibitor (SI) analysis is an extremely important part of scale management and, in recent years, much work has been done on the development of specialist scale inhibitor analysis techniques like Liquid Chromatography Mass Spectroscopy (LCMS) to push the boundaries of low level scale inhibitor detection. However, LCMS requires costly and complex instrumentation and there was therefore still a need for the development of other advanced techniques like fluorescence (F) and Time resolved Fluorescence (TRF) that can be used on site to provide near "on line" data. Fluorescence techniques are particularly suited to tagged polymers and naturally fluorescent molecules like polyamines whereas the operation principle of TRF is based on interactions between lanthanide ions and various functional groups of polymer or phosphonate scale inhibitors. Both techniques work individually or in combination and this provides a distinct advantage for multiple scale inhibitor analysis in produced brines that enable the design of packages of different products for specific field applications. In addition, TRF and fluorescence techniques offer the capability of on-site detection compared to the majority of scale inhibitor analysis techniques and other advanced methods like LC-MS. The ability to detect both phosphonate and polymeric scale inhibitors at very low MIC (<1ppm) has the potential for significantly extending scale squeeze lifetimes. This has now also allowed highly efficient, F tagged polymers, to be used in field situations where scale squeezing was either stopped or the lifetime was significantly compromised because of the lack of confidence in the residuals analysis. Specific field and theoretical examples from both sub-sea and conventional wells will be presented where the application of both advanced fluorescence and TRF techniques has shown significant improvements in scale management. This paper will compare and contrast the pros, cons and limitations of both fluorescence and TRF techniques for both phosphonate and polymeric scale inhibitors. In addition, it will highlight examples where scale management significantly improves through the application of Fluorescence and/or TRF scale inhibitor analysis techniques in complex production scenarios.

Accurate detection of scale inhibitor residuals from produced waters is a critical part of flow assurance. Tagged scale inhibitors have been developed to improve the detection limit. The purpose of having multiple different tags on the same inhibitor chemistry is to be able to separately detect the level of inhibitor for several subsea templates when commingled in a single flow back line to a production facility. These new tagged scale inhibitors combine the excellent scale inhibition performance of sulphonated copolymers with fluorescence technology, delivering lower detection limits of residual inhibitor concentrations.The authors have developed a testing protocol that enables accurate detection of two tagged scale inhibitors from a produced water sample using fluorescence spectroscopy. The development of the chemistry and detection monitoring technique, and the results demonstrating the validity of the analysis method are discussed. The method has been validated and tested with real produced water samples collected from a subsea field in the North Sea. The samples were spiked with unknown concentrations of two fluorescent tagged sulphonated copolymers with concentrations between 0 and 200 ppm as product.The tested products have specific excitation and emission wavelengths, enabling the independent detection of both products with a fluorometer without any disturbing effect. The test results clearly show that the protocol can be used for analyzing low concentrations of scale inhibitor polymers from produced waters. The final goal is to analyse residual inhibitor concentrations using a portable fluorometer delivering onsite detection, and thus enabling real-time monitoring of the scale inhibitor squeeze returns.This fluorescence technology can be used in combination with a phosphorus tagged scale inhibitor and ICP analysis method to detect three products from the same commingled sample. The validity of the protocol has been confirmed and has generated great interest in the oil and gas industry where accurate detection will maximize safe and economic oil production.

Scale inhibitor (SI) analysis is an extremely important part of scale management and it is essential to have reliable methods for the accurate and precise measurement of scale inhibitor residuals in produced fluids in order to prevent wells from scaling. This information enables key decisions on the efficiency of scale squeeze and continuous chemical injection treatments especially in remote environments. In remote fields, such as in desert and extreme winter environments, the ability to be able to monitor scale squeeze residuals on-site would offer significant potential to improve scale management capability through provision of rapid data which otherwise might not be available for several weeks due to long sample transport times to the laboratory. Since conventional scale inhibitor analysis methods are not suited for on-site analysis this has led to the development of a toolbox of technology options including suitable scale inhibitor squeeze chemistry coupled with advanced, on-site, "near on-line" scale inhibitor detection procedures including Fluorescence (F) and Time Resolved Fluorescence (TRF). In this paper, two field examples for on-site TRF analysis of polymeric scale squeeze inhibitors from remote wells in harsh environments will highlight the benefits of quick and timely scale inhibitor residual information. In the example from remote desert wells, a comparison of TRF and High Performance Liquid Chromatography (HPLC) analysis of the polymer residuals will show the accuracy and precision of the TRF method at low SI levels. In addition, an example for the proof of concept of detection of three different F Tagged sulphonated polymers in the presence of a phosphonate squeeze inhibitor and continuously injected untagged polymer will demonstrate the ability of "near on line" fluorescence techniques to improve scale management where four subsea wells are co-mingled in the same flow line. This paper concludes that fluorescence techniques are particularly suited to tagged polymers and naturally fluorescent molecules whereas Time Resolved Fluorescence provides the ability to detect untagged scale inhibitors like sulphonated copolymers, phosphonates and phosphate esters. The two techniques can be used individually or in combination with each other and, in addition, offer the advantage of being able to detect polymeric and phosphonate scale inhibitors to minimum inhibitor concentration (MIC) of 1-2ppm and <1ppm respectively which offers potential to extend treatment lifetimes.