A holistic approach to locating your desander
The location of your desander can have far-reaching consequences. The further upstream it can be located; the less sand challenges will be encountered downstream..
By Aksel Skåland, BD Manager, FourPhase
Where to locate the desander on any sort of oil and gas installation is a complex issue with many variables. A holistic approach is necessary, as the location of the desander has multiple impacts on produced oil, gas and water that should be considered closely. In this article, we will provide some pointers on the pros and cons of alternative locations for desanders.
By Aksel Skåland, BD Manager, FourPhase
Where to locate the desander on any sort of oil and gas installation is a complex issue with many variables. A holistic approach is necessary, as the location of the desander has multiple impacts on produced oil, gas and water that should be considered closely. In this article, we will provide some pointers on the pros and cons of alternative locations for desanders.
Alternative 1: As far upstream as possible
Our general recommendation is to locate your desander as far upstream as possible, as this location will generate multiple benefits downstream. Removing sand upstream of any production separator(s) will eliminate sand accumulation in separators, erosion issues on pumps, valves and other equipment and reduce the need for manual intervention with sand removal.
There may of course be many valid reasons for not locating your desander directly on the wellhead or production manifold. Multiple wells with separate risers/manifolds, desander size in relation to installation space, only one sand producing well among multiple wells etc. With many wells streaming into a production manifold, an optional location is also immediately downstream from the manifold.
ESG issues can benefit significantly from desanding upstream of the production separator. The safety factor should not be underestimated, as removing sand before the separator prevents sand buildup in the separator and thus the need for physical sand removal. For separators that are not equipped with, or have malfunctioning jetting systems, this entails sending personnel with Personal Protective Equipment (PPE) into the enclosed space of the separator with shovels and buckets during a turnaround. The risk is high, associated safety procedures are time consuming, and the whole concept of manually emptying the separator is outdated and should ideally not be part of modern offshore operations.
There may of course be many valid reasons for not locating your desander directly on the wellhead or production manifold. Multiple wells with separate risers/manifolds, desander size in relation to installation space, only one sand producing well among multiple wells etc. With many wells streaming into a production manifold, an optional location is also immediately downstream from the manifold.
ESG issues can benefit significantly from desanding upstream of the production separator. The safety factor should not be underestimated, as removing sand before the separator prevents sand buildup in the separator and thus the need for physical sand removal. For separators that are not equipped with, or have malfunctioning jetting systems, this entails sending personnel with Personal Protective Equipment (PPE) into the enclosed space of the separator with shovels and buckets during a turnaround. The risk is high, associated safety procedures are time consuming, and the whole concept of manually emptying the separator is outdated and should ideally not be part of modern offshore operations.
Alternative 2: De-sanding produced water
Produced water from separators may contain a variety of substances, including sand that has not settled in the separator. Depending on the legal and environmental regulations valid for the location of the installation, produced water may need to be processed to comply with regulations for discharge to the surroundings or for reuse.
At a gas and condensate installation on the Norwegian Continental Shelf, we have a FourPhase 5K DualFlow desander located on the water line from the production separator. The purpose of the desander is to remove sand and solids from the water to be reinjected in the reservoir. Norwegian regulations specify that reinjected water should meet certain purity standards to avoid bacteria growth and H2S gas in the reservoir, and often solids need to be removed to comply.
An additional benefit is to protect the reinjection pumps from the erosive and abrasive sand. In a published case study (link), we describe how a North Sea operator encountered recurring failures of their reinjection pumps, causing unwanted shutdowns and non-productive time for the platform and nearby fields delivering through it. A DualFlow desander removed the sand that caused the pump failures, resulting in increased uptime and production.
At a gas and condensate installation on the Norwegian Continental Shelf, we have a FourPhase 5K DualFlow desander located on the water line from the production separator. The purpose of the desander is to remove sand and solids from the water to be reinjected in the reservoir. Norwegian regulations specify that reinjected water should meet certain purity standards to avoid bacteria growth and H2S gas in the reservoir, and often solids need to be removed to comply.
An additional benefit is to protect the reinjection pumps from the erosive and abrasive sand. In a published case study (link), we describe how a North Sea operator encountered recurring failures of their reinjection pumps, causing unwanted shutdowns and non-productive time for the platform and nearby fields delivering through it. A DualFlow desander removed the sand that caused the pump failures, resulting in increased uptime and production.
Alternative 3: De-sanding produced oil
If – for any number of reasons – it is impossible to locate the desander further upstream, a good alternative is locating the desander on the oil line from the separator. This is a solution we have come across in some instances. Desanding the oil line does not solve the challenges of sand buildup in the separator but ensures that oil moving downstream is without solids that may have detrimental effects on downstream installations and processing facilities. For instance, where platforms are delivering production to other assets but are experiencing sand production this can lead to sand build-up on the export line. By installing a desander upstream of the export line you can mitigate the associated risks with sand plugging the flow line.
A FourPhase desander installed on the oil line ensures that sand is removed in the desander for further processing. The sand output from the desander is typically re-injected to a disposal well or sent to shore for disposal in closed containers according to environmental regulations.
A FourPhase desander installed on the oil line ensures that sand is removed in the desander for further processing. The sand output from the desander is typically re-injected to a disposal well or sent to shore for disposal in closed containers according to environmental regulations.
Alternative 4: De-sanding produced gas
Desanding of produced gas is typically not required as the gas phase is normally separated from any solids in the production separator. We have so far not encountered any fields or special circumstances where the gas line of an oil and gas-producing installation needs to be desanded.
But purely gas-producing wells are another ballgame. Some natural gas reservoirs, especially those in sandstone formations or unconsolidated sand reservoirs, may contain loose or unconsolidated sand grains present in the formation rock. If there is enough loose sand, sand slugs may form. These slugs are essentially concentrated accumulations of sand or solid particles that are carried along with the flow of natural gas. Sand slugs can lead to operational issues, increased maintenance requirements, and potential production downtime. In a brownfield offshore well in the Caribbean, FourPhase desanders enabled the operator to restart the well from shut-in to yield 13 MSCF daily and reap significant additional revenue. (Link to case study)
But purely gas-producing wells are another ballgame. Some natural gas reservoirs, especially those in sandstone formations or unconsolidated sand reservoirs, may contain loose or unconsolidated sand grains present in the formation rock. If there is enough loose sand, sand slugs may form. These slugs are essentially concentrated accumulations of sand or solid particles that are carried along with the flow of natural gas. Sand slugs can lead to operational issues, increased maintenance requirements, and potential production downtime. In a brownfield offshore well in the Caribbean, FourPhase desanders enabled the operator to restart the well from shut-in to yield 13 MSCF daily and reap significant additional revenue. (Link to case study)
Knowledge through sand monitoring
FourPhase provides real-time monitoring of unmanned desanders, providing extensive data on the solids production, frequency, and amounts. Our remote monitoring lets the customer better understand solids production from their wells, enabling increased production, more accurate calibration of their sand sensors, and improving their understanding of production.
FourPhase has established a comprehensive set of remote monitoring capabilities to provide customers with digital options in the broad industry move to remote and unmanned operations. This means that FourPhase can provide autonomous and/or remotely monitored desanders that contribute to lowering risk and reducing Personnel on Board.
FourPhase has established a comprehensive set of remote monitoring capabilities to provide customers with digital options in the broad industry move to remote and unmanned operations. This means that FourPhase can provide autonomous and/or remotely monitored desanders that contribute to lowering risk and reducing Personnel on Board.