On-line Water Flood Sulphate Measurement via Raman

Current offshore, water flood technology requires sulphate removal to fairly low levels (~ 3 to 40 ppm). Process Instruments (USA) offers a continuous, on-line method for sulphate analysis in flood water projects, using their Raman scattering technology.  The method requires no consumables, no special sample handling, the instrument automatically calibrates itself and includes built in redundancy for unattended, long- term operation.  Offshore experience of > 6 years demonstrates typical down times of < 2 hours/year.  Equipment can be calibrated for different sulphate ranges, but 1 to 80 ppm is typically used, with an accuracy of ~ 1 ppm.

Sampling times are ~ 10 minutes/stream, with the capability of monitoring many streams from one instrument. Sample flow cell and wettable surfaces are normally fabricated in 316 SS, with other alloys available upon request. Flow circuits are rated up to 250^oC and 3000 psi (200 Bar).  Electrical equipment runs on 120 to 240 AC, and is certified ATEX and IEC Ex, for zone 0 applications.

Normally, the Raman equipment is located in an air conditioned control room, and fibre-optic cable is run to the various sampling points which can be up to ~ 800 ft (250 m) away. Sulphate levels are sent via Modbus to DCS using TCP/IP, RS 485, or 4-20 mA communication protocols. Remote operation over a network is also available.   Equipment includes a 2 year warranty, with on-site installation, calibration and training.