Have you ever considered the effect the oil and water separator has on the efficiency of oil production? And have you ever considered investigating ways to optimize the separator operation in order to increase oil production?
By increasing the utilization of the assets available in the production process plant, you can increase the level of produced oil. One of these assets, and perhaps the most important one, is your oil and water separator.
In this article I will show you why the oil and water separator affects the rate of the oil production, and how you can increase the production by changing the way you utilize your oil and water separator.
In oil production, water is considered a by-product. There is no market for oil with high levels of water in the mix. Therefore, it is necessary to separate the water as accurately as possible from the oil before the oil production companies can take their oil to market.
It is common knowledge that water and oil does not separate very well. Just have a look at the French dressing in your refrigerator. You will see that the oil floats on top of the water with an emulsion and herb in the mix, and you need to shake the bottle well before you pour it on your salad.
The same principle applies to crude oil production. Given time, the oil and water in the fluid stream pumped up from the oil wells will separate by themselves. However, waiting for this natural process does not allow for a profitable oil production for several reasons.
To compensate for these factors, and allow for a more profitable oil production, all oil production plants include separators.
The purpose of the separator is to separate the fluids from one or more well streams into oil, water and gas, as controlled and as quickly as possible. The speed, or residence time, of the separation therefore has a direct effect on the efficiency of the oil production. Consequently, the overall efficiency of the separator affects the oil production rate.
Suggested reading: How does an oil and water separator work in oil and gas production?
Even though the separator is vital to the oil production, it is often described as the bottleneck of the production process.
Why is this?
A bottleneck is said to be a point of congestion in a production system.
The separator is a “blind” piece of equipment, it is not flexible at all. Basically, it is designed to receive a multiphase fluid stream, separate all its elements (oil, water, gas and solids) and dispose of the unwanted products (e.g. the water). Should anything happen to the surrounding process and environment conditions that causes a need to adjust the separation process (something goes wrong), it will slow down the production. This because the separator is intrinsically not flexible to handle all the possible uncertainties and unforeseen circumstances. Should these occur the operator has to adjust the inlet valve opening to decrease the fluid flow, or increase the injection of chemicals. This will allow the separator to get back into its optimal operating envelop, however it will also cause a decrease in production rate. Hence, the separator is a bottleneck in the production process.
As mentioned above, the separator must function in an everchanging environment, that is the oilfield will experience changes throughout its life span (like environmental, seasonal, changes to the well stream, etc.). To accommodate these changes, todays separators operate with spare capacity. So, most of the times the separator runs at a 70-80% of its nominal capacity. In other words, they are built larger than necessary to ensure a production as stable as possible. The remaining 20-30% capacity allows the operator to adjust for any upset conditions.
This means that while producing, you are not utilizing your separator to the maximum. So the possibility of increasing oil production solely by making changes on how you utilize the separator, is a fact.
So how do you solve the bottleneck issue in a better way to increase the utilization and the oil production?
Clearly, the simplest answer would be to scale down, build a smaller separator, and thus reduce the costs and improve the asset utilization.
However, this does not solve the issues related to changes in the oilfield. Nor does it solve your problems if your separator is already built and fully operating?
Suggested reading: Instrumentation for Oil and Water Separators: Just a Cost or a Great Investment?
There are three important factors that allow you to get as much value out of your separator as possible. They are equally important and highly connected, and you can consider these weather you are dealing with a new project or a retrofit for an existing oil field.
The separation process takes place within your separator vessel. The separator is as mentioned a “blind” piece of equipment, thus you cannot see what is going on inside of it.
The operator at the production plant is therefore charged with the task of predicting what is going on within the separator vessel in order to adjust the separation process without reducing the production.
If the operator does not know the exact water, emulsion and oil levels within the separator vessel he/she risks, for example, discharging to much oil with the water. This is bad for the oil production rate. In addition, it pollutes the surrounding environment. Another risk is to produce oil with emulsions, with the consequence of having too high-water content in the produced oil.
To compensate for the risk of disposing too much oil with the water it is common practice to keep the water level thicker than what is strictly necessary, making the separator underperform.
You remedy this by knowing what is going on within your separator in real time.
If you equip your separator to gather data from inside your separator the thickness of the water layer, emulsion layer, oil level etc. will be known. This allows the operator to optimize the operation conditions within the separator and reduce the water layer without risking spilling oil when discharging the water. At the same time having a very little layer of water and emulsion allows for an increase of the fluid flow into the separator, thus increasing the oil production.
If the operator at the oil plant can measure the exact layers (water, emulsion, oil, gas, etc.) inside the separator at any given time, the production process is fully under control.
This insight will also allow the operator to adjust the production process accordingly when upset conditions occur, without having to reduce the flow rate of the fluid stream into the separator, allowing the separation process to quickly adapt to upset conditions.
Without the knowledge of what is going on within the separator the level of uncertainty linked to any oil field conditions will affect the production rate as it takes time to adjust to changes or upset conditions.
With the right tools that allow you to know what is going on within the separator, and at the same time remove uncertainties from the production process, will let you utilize the remaining 20-30% capacity of your separator, as you no longer need this as a buffer.
The math here is quite simple. By utilizing 20-30% more of your separators operating capacity you consequently also increase your processing capacity by 20-30%. This allows you to substantially increase the oil production rate.
Investing in equipment that lets you gather data on what is going on within the separator is a way for you to utilize the assets available in the production process to a maximum.
This will also allow for a rapid payback on your investment when building the oil and gas separator, as you can optimize the process, maximize the use of the equipment, and increase the production.
Suggested reading: Why You Need to Select Instrumentation for Your Oil and Water Separators During Early Phase Design
The key take away here is, that you should know what is going on within your separator in real time.
To do this you need to dynamically collect all the data on conditions like temperature, pressure and the various fluid levels within the separator, where the interface levels are the most important.
The best way you can achieve this insight is by adding advanced instrumentation to your separator.
There are many different instrumentation technologies available on the market today, some more advanced than others. Your challenge is to choose the right technology available for your separator that will give you the data you need to ensure the maximum utilization of your separator and at the same time ensure a high ROI (return on investment).