A novel in-line fibre-optic sensor for the detection of hydrate inhibitors within the oil and gas industry

An in-line fibre-optic fluorescence-based sensing methodology for the detection of two common thermodynamic hydrate inhibitors (THI), monoethylene glycol (MEG) and methanol (MeOH), used in the oil and gas industry has been developed. The fluorescence properties of two solvatochromic indicator probes were determined with varying ratios of THIs within oil-in-water mixtures. Sensor performance was evaluated for varying oil type, oil concentration and solution salinity to mimic the chemical composition of an oil flow line. Finally, an inline sensing capability was demonstrated using a purpose built industrial flow loop system with the results obtained showing that the concentration of known THIs can be determined to within 5% in the 0-50% THI concentration range. This measurement method has opened up the possibility of controlling hydrate inhibitor concentration in real-time, leading to improved flow assurance and substantial economic benefits.