Separators can over the length of field life be exposed to operating conditions outside the set design conditions, which can cause operating issues in terms of separator efficiency, operating expenditures and potential need for frequent maintenance and/or retrofitting new internals. In mature operations with heavy oils, there can be severe issues with Water-in-Oil and Oil-in-Water emulsion layers. In late life operations, enhanced oil recovery (EOR) efforts with polymer injection can also take place to produce more, but at the same time making the separator function in terms of phase separation even more complex. Emulsion thickness and residence time optimization in separators and tanks are key issues in the oil and gas operations. Real-time data of the full level profiling is complicated and has been based on instruments with varying reliability and performance. Operations have been relying on other process parameters and bottle tests. However, in this work, separator profiler utilizing electrical tomography was used for monitoring separator content online, especially fluid interface levels as well as emulsion and foam layer thicknesses. In addition, effect of polymer injection to the wells is investigated. From the single profiler, data for the separator fluid levels, emulsion and foam thicknesses can be derived.
The profiler used is a safe-to-use non-radioactive probe-type measurement sensor which is installed through an existing separator nozzle. The actual separator profiler with dimensions 5 cm diameter and 3 m length was installed downstream of the inlet cyclones and the flow distribution baffles in the three-phase separator located at one of the production fields in the Middle East. Water-oil interface, turbulent water-in-oil dispersion band, oil-gas interface and foam layer thickness were monitored continuously for several months with varying flowrates and operation conditions. Later, effect of polymer injection was also investigated. Interface level and layer monitoring results will be given and discussed.
The results show that the profiler is highly useful for monitoring the separator fluid distribution online, building a rigid data analytics model over time that can be utilized by the operations to improve and optimize the performance.
This paper shares novel information on operational experience of data analytics used for three-phase separators operating in a heavy oil field with polymer injection. The sensor type used is novel to the industry with high robustness and reliability generating multiple data points per second, enabling a highly detailed analytics model generating new possibilities for operational optimization through digitalization. In addition, commissioning and monitoring of the sensor was done remotely during covid-19 shutdown without the need of external personnel entering the field demonstrating remote commissioning and digital oil field concepts.