Why Some Water Cut Meters Do Not Work, and How to Avoid Great Damages

In oil and gas, the instrumentation applied in the process system is an important element of the process control and safety. It allows for real time monitoring and facilitates fast control actions to the different parts of the process system.

By using a water cut meter, you can get quality data and thus prevent major failures or shutdowns and, at the same time, guarantee optimal production quality and productivity. You’ll get higher efficiency and lower risks.

However, some water cut meters might fail. In this blog article, we will discuss why this can occur, potential consequences, and how to avoid damages.

Customization to get quality data

The oil and gas industry has one intrinsic characteristic – all the oil and gas fields are different from each other. In fact, despite all being classified as oil and gas fields, they hold fluids with different chemical and physical characteristics. The API gravity in oil for instance, can be classified as ultra-light, light, medium and heavy, while looking at its sulfur content it can be classified as sweet, medium-sour and sour. Then, depending on the pressure, it can be defined as high, normal, or low pressure. The same type of classification is done for the temperature.

The produced fluid can be exclusively liquid, with oil and different percentage of water, or multiphase, meaning it contains both oil, water, and gas. In many cases there is also the presence of solids, aggressive gases (H2S and CO2) and emulsions.

Therefore, there are no copy / paste solution for your application.

Consequently, this type of differences has led to an industry that has developed and continue to develop products and technologies with a large variability of options and customizations. There is no one instrument with a single design that can be applied successfully in any type of field or application.

What to consider

As stated, there is no such technology perfect in all scenarios. Thus, making an assessment of the application and the type of fluid is crucial when choosing the right technology for your operation. Ask yourself these questions:

• Do you deal with highly processed fluids?
• Multiphase flow with presence of emulsions, sand, oil, water, and gas?
• Is there mostly oil?
• Light or heavy oil?
• Mostly water?
• Sour and aggressive components?
• Is it high temperature?
• High pressure?
• Or simpler, more stabilized fluid?

If you fail to ask yourself these questions before selecting a water cut meter you will most definitely encounter problems.

Suggested reading: Real Time Well Monitoring: Why is it so Important? 

Reason for instrumentation malfunctioning

So, what is the reason why some water cut meters simply do not work?

Failure and lack of accuracy happen when you choose the wrong meter for your application and install the instrument in the wrong place. A meter could perform perfectly well in one application, in another it can perform average, and in some cases - not perform at all.

Consequences

Despite the instrument being perfectly functioning, the application will define the result – the accuracy (the quality) of the data generated.

If you apply the instrument in the wrong place, you will get inaccurate data and when you get inaccurate data you will misunderstand the behavior of the process system during monitoring.

For instance, you can think that you have a production with high hydrocarbon and low water content, but in reality, the produced water is much higher than expected. This type of wrong assessment will have big and direct economic consequences because transporting water longer than necessary will reduce the overall production and processing system efficiency, resulting in additional dewatering activities and reduced hydrocarbon production.

Another typical wrong assessment made by the water cut meter is when there is less water in the system than actually measured by the instrument. This type of wrong measurement typically leads to higher chemicals consumption than needed, with the direct consequence of higher OPEX.

An even bigger economic consequence is that you can make decisions based on inaccurate data that could lead to an accident, causing loss of production and environmental damages.

The experience demonstrates that in most of the cases when the instrument provides very wrong measures and low-quality data, many operators choose to shut down the device and operate the system without it, believing that receiving no data is better than getting the wrong data.

Suggested reading: How to Convince Your Project Team About the Added Value of Instrumentation

Solution

Experiencing instrumentation malfunctioning / non-properly reading is due to a lack of assessment in the early stage of the project. Often, deciding what instrumentation the application really needs is being pushed to the end of the project schedule, limiting the available choices due to lack of time and budget.

But what do you do if you already have a water cut meter, but after a period of production discover inaccuracy?

Typically, the fluids’ elements that affect the functionality or accuracy of an instrument are the components that have changed along with the production. If there is a problem, you need to do a simpler assessment to identify the main elements that create the problems for the instrument. This could be gas, higher amount of water than expected, presence of sand, multiphase flow, or dirty components that creates obstruction to the sensor. Identifying the problem is the first step to finding a fitting instrumentation before it is too late.

Conclusion

Apart from doing a good assessment before any project starts, it is fundamental to monitor the field evolution during the production phase, because the reservoirs performance and the characteristics of the produced fluids can heavily affect the measuring capability of the instrumentation utilized in the facility.

Every operator has the responsibility to monitor how the field is performing, checking any critical components, and staying ahead of the problems. For instance, if the water is increasing constantly, you will know that in a couple of years, you will need an instrument able to handle a greater amount of water than what is present today, most probably in a water continuous flow.

It is difficult to exactly predict what will happen and when, but if you constantly monitor, you will have an understanding of what might possibly happen and adjust thereafter.