On-Site Analysis of Scale Squeeze Inhibitors in Remote Environments UsingFluorescence and Time Resolved Fluorescence

摘要

Scale inhibitor(SI)analysis is an extremely important part of scale management and it is essential to havereliable methods for the accurate and precise measurement of scale inhibitor residuals in produced fluidsin order to prevent wells from scaling.This information enables key decisions on the efficiency of scalesqueeze 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 monitorscale squeeze residuals on-site would offer significant potential to improve scale management capabilitythrough provision of rapid data which otherwise might not be available for several weeks due to long sampletransport times to the laboratory.Since conventional scale inhibitor analysis methods are not suited for on-site analysis this has led tothe development of a toolbox of technology options including suitable scale inhibitor squeeze chemistrycoupled 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 fromremote wells in harsh environments will highlight the benefits of quick and timely scale inhibitor residualinformation.In the example from remote desert wells,a comparison of TRF and High Performance LiquidChromatography(HPLC)analysis of the polymer residuals will show the accuracy and precision of theTRF method at low SI levels.In addition,an example for the proof of concept of detection of three different F Tagged sulphonatedpolymers in the presence of a phosphonate squeeze inhibitor and continuously injected untagged polymerwill demonstrate the ability of"near on line"fluorescence techniques to improve scale management wherefour subsea wells are co-mingled in the same flow line.This paper concludes that fluorescence techniques are particularly suited to tagged polymers and naturallyfluorescent molecules whereas Time Resolved Fluorescence provides the ability to detect untagged scaleinhibitors like sulphonated copolymers,phosphonates and phosphate esters.The two techniques can beused 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 1-2ppmand <1ppm respectively which offers potential to extend treatment lifetimes.