Challenges for Water Quality Measurement for Produced Water Handling Subsea

摘要

Subsea processing and separation of produced water from oil and gas is an innovative and effective technology that contributes to maximizing recovery of offshore oil and gas resources. Separating water at the seabed and then either disposing of it via subsea re-injection or discharge offers many advantages in terms of flow assurance, easy separation, reduced use of production chemicals, and saving on energy (by not bringing the water to the surface). For a wide take-up of subsea processing systems, water quality measurement is critically important.rnDespite the success of Troll pilot and also the first full scale system at Tordis by Statoil, it is clear that there is still a technology gap regarding subsea water quality measurement instrumentation. Without such devices, monitoring of water quality can only be achieved by taking subsea samples using ROVs (Remotely Operated Vehicles) and bringing them up to the surface for analysis. This is not only extremely expensive and time consuming, but more importantly it does little to help oil production that requires continuous and timely data for control and operations.rnThere are many challenges in developing reliable and accurate subsea water quality measurement devices. These challenges lie in the fact that they will need to work reliably at a water depth as much as 3000 m with the temperature and pressure of process fluids far higher than that experienced on the surface. Testing and qualification will play a vital role in the technology development and deployment. Standards have now being developed for testing and qualifying subsea equipment. A number of Joint Industry Projects (JIPs), which aim at accelerating the development and deployment process of these technologies, are underway. These JIPs are thought to offer the best routes to close the technology gap.rnThis paper provides an overview of the current state of subsea separation and produced water re-injection (PWRI) (and/or discharge) practices and the challenges faced by the industry in developing subsea water quality measurement devices. The paper presents information and findings from a recently completed JIP relating to potential subsea water quality measurement technologies, functional specifications, and qualification test requirements.