In a saltwater disposal facility, frac trucks deliver saltwater and frac flowback from the field which is fed into a disposal well through a treatment plant. The wastewater unloaded from the truck immediately goes into a gun barrel separator (battery) where water and remaining oil are naturally separated. Additional heavy oil downstream in the facility is eventually fed back into the gun barrel separator, creating a dynamic emulsion layer. It is imperative that the oil is separated from the saltwater prior to injection into the spent well.
This blog post, part of a Magnetrol® series on interface based on our new white paper, describes common issues in measuring the emulsion layer in saltwater disposal facilities and some solutions to improve measurement accuracy.
The oil-water separation in the gun barrel separator and any downstream unit is critical. If oil carries over into the disposal well then it can damage or plug the well, requiring rework costs and downtime as well as an increase in chemical costs used in the treatment process.
Having a clearer understanding of the day-to-day storage of “unwanted” liquids in the tank battery (pending disposal) versus production capacity allows for better management and utilization of resources, such as trucks getting dispatched to remote sites with sufficient capacity. Wellsite automation becomes imperative with instruments that can communicate through the desired protocols, are faster to commission and require little power to cycle up and down quickly.
In addition to the saltwater disposal fee, the separated oil represents additional revenue for the company. Since the injection well is porous by nature, any residual oil in the saltwater limits its capacity and eventually the well must be reworked at a significant cost.
After the gun barrel separator, the oil-water emulsion is passed into a treatment unit while the top layer of oil is sent to a separate holding tank. The Eclipse® Model 706 guided wave radar (GWR) transmitter effectively measures the oil level in the gun barrel tank, as well as the top of the oil-water emulsion, ensuring that the different products are routed to the appropriate units. This in turn prevents potential downstream plugging of the disposal well and reduces chemical treatment costs. Additional GWR transmitters or non-contact radar devices can then be utilized for the standard total level measurements.
For more information on level measurement solutions for interface and emulsion layer applications, download the interface white paper.