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How a smart desander can enable optimised production in a solids producing well
14 July 2022
It’s estimated that 70% of wells globally are located in a poorly consolidated sandstone reservoir¹, this can lead to solids related issues. This means that across the sector, it is very common for wells to be flowing at reduced production to keep below the lift rate for solids. While this process ensures solids do not enter the production facility, it also reduces production efficiency.

In this article we will look at what causes solids, as well as presenting the “classic” solution to manage solids. For wells that are flowing at a reduced rate, we will also discuss how optimal production can be restored, and in some circumstances increased.
What causes solids in the wellbore
Solids are caused by poorly consolidated particles in the formation. Poor reservoir consolidation can be impacted by varying flow, gas coning, well age and water breakthrough. The movement created by any fluid, such as water or gas, in the reservoir can have a big impact. Its presence, together with the drawdown of the well, viscosity and velocity of the fluid means the particles can break free, allowing sand to flow in the wellbore.
The ‘classic’ solution to manage solids
When solids are anticipated as part of the life of the well, the classic solution is to install screens as part of the well construction. While effective in some instances, there are two core issues that can arise with the use of screens.

• Erosion – Screens are subject to erosion and wear and tear.
• Particle size – Screens are set to capture particles of a specific size. If the particle size is bigger than the screen allows, it can cause a blockage at the screen itself. If the particle size is too small, then the particle will get through the screen and enter the pipe.

Because of the above, screens are prone to failure and solids issues are highly likely to enter the production facility.

1. Sand detectors are installed on the flowline, so the operator can ensure sand production is always monitored.
2. Once the sand detectors show an alarm, the well can then be routed into the test separator to measure how much solids are being produced.
3. If the volume of solids is too high, the well can be choked back to a lower flow rate. This process reduces the production rate from the well and puts the production rate below the lift rate for the solids.

The well will then continue producing (at the lower flow rate) until the alarm goes off again. However, this does not mean that the solids production have stopped. After some time, the wellbore may become plugged with solids. To remedy this situation heavy intervention, such as a coiled tubing cleanout, would be required.
Optimising production in a solids producing well
To optimise a well during production, the flow rate needs to be maintained. Instead of preventing the removal of solids, a smart desander (such as the DualFlow 5K) extracts the solids at the surface. When it is installed, it is normally placed between the well and the separator. The system can be connected to any of the valves on the x- tree.

The process is carefully controlled and managed, with the data from the smart desander used to monitor the situation in the reservoir. The production rate is increased over the lifting rate for the particles so they can be transported out of the well. At this point, the desander topside can handle the solids removal. Carefully, slowly, and steadily the rate increases back to the optimal rate. This rate is normally the old production rate before they started choking back the well.

The flow rate can then be kept at the optimal rate, even though it is above the lift rate. This is because any solids will be separated with the smart desander, and clean fluid will go to the separator.
The potential to increase production above the initial rate
An added benefit to using a smart desander is that sometimes the well becomes more permeable. This is particularly evident on wells where solids are continuously produced out of the reservoir in a controlled manner. This means that the well’s health has improved because of the particles being removed from the reservoir. If the well is more permeable, it is possible to start increasing the production rate, even above the initial rate.

The process of increasing above the initial rate can happen because the solids are produced very carefully out of the well. This is achieved through careful analysis of data from the desander sensors. If managed properly, it’s possible to increase production above the original flow. To achieve this, insights from the real-time data provided by the smart desander are used to manage the process.
The value case of using a smart desander to optimise well production
• By managing the solids topside, hydrocarbons can be extracted at a faster rate, meaning the recovery efficiency of the well can be increased. This enables a more efficient timespan than originally planned and reduces overall operating costs.

• Using data and sensors, a smart desander can calculate the volume of solids that is received on the return. This means that operators can quantify the solids and gain a more accurate picture of what is happening in the reservoir.

• Any solids that are present are produced safely out of the well, and there is a chance that the well will become more permeable.

• The operator has full control of the process, ensuring solids management is controlled at all times, increasing HSEQ.

• Smart erosion software is built into some smart desanders, such as the DualFlow 5K. This means that equipment is managed against the threat of erosion, and its lifespan can be maximised. Erosion software can be used to predict when wear and tear will occur. This means maintenance can be handled in a proactive rather than reactive manner and significantly reduces the need for replacement of parts.

• Smart desanders are controlled by automated systems, meaning that the number of POB is reduced. This eliminates costs, further improves HSEQ and is positive from an ESG perspective.
¹Shouwei Zhou and Fujie Sun, Sand Production Management for Unconsolidated Sandstone Reservoirs 1st Edition, Wiley- Blackwell, 2016
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