Water is the largest biproduct in the oil industry, and the element that causes most problems – it’s an unwanted product that you have to deal with and that you want to dispose of as soon as possible, to avoid transporting it unnecessarily further into the plant. Understanding how much water there is at a specific moment and place is fundamental for efficiency and to avoid risks.
In this blog, we will discuss why it’s crucial to monitor water cut directly at the well, and what benefits you’ll have by continuous monitoring with online instrumentation.
The producing well
Before digging into the monitoring, we’ll have a quick look at the behavior of the wells, with particular focus in this article to the most relevant one – the producing well.
As an oil and gas professional, you already know that to develop any type of field, you need a number of wells to produce the hydrocarbon present in the field itself. What the operators have done so far in history is to estimate the amount of water, then utilize software to calculate the water from other parameters (e.g., temperature, pressure, flowrate etc.), and lastly do sampling – sending people to the well to take physical samples on a regular time basis (e.g., once a day, once a week etc.).
However, the composition of the fluid in the well is constantly changing.
The pressure is naturally reducing over time, with following change in the amount of water and gas released, consequently making it impossible to precisely predict and anticipate how the composition of fluid coming from the well will be in two weeks, in two weeks or in two years.
In addition to the day-bay-day changes in the well production, there are also differences on when in the well’s life cycle the production is at its peak. You can have one type of well that is able to produce large quantities of hydrocarbon at the beginning of their life, and gradually reducing pressure and flow. Others can at the start produce mostly oil, but due to the pressure decline inside the reservoir, over time they release more water and/or gas.
It’s impossible to precisely predict these changes, even with a 4D software modeling tool, due to their lack of accuracy in absence of real data.
So, when do we have a real problem in production?
At one point, all wells will face water breakthrough, consisting of a sudden increase of produced water, and at that point the water itself become predominant in the produced fluid. This type of event requires maintenance of the well, and often a well temporary shutdown.
If the shutdown happens too late, a lot of water will have already been produced resulting in the downstream gathering and processing system being full of water. The operator then has to shut down the well for days so to let the reservoir settle before they can restart the production. From an efficient production perspective, this is clearly not ideal, not to mention the risk of serious accidents.
Being able to anticipate this water breakthrough, the trending of the behavior of the produced water, will help the operator to avoid unnecessary pause of production or shutdown.
Most wells are equipped with temperature and pressure instrumentation, but rarely instrumentation to directly measure water content of the fluid. We have discussed several scenarios that can go wrong in a producing well. Clearly, monitoring the individual wells is fundamental for numerous reasons:
Reduce risk of accidents
Know what amounts of chemicals to inject into the producing line
Reduce staff cost
Reduce well maintenance cost
Today, the technology of acquiring data, sending data and analyzing data is so powerful that installing an additional device in each well will create a long-term benefit and help avoid shutdowns, accidents and unnecessary cost.
Digitalizing the hydrocarbon field production is crucial for the Oil Companies to stay competitive in the market and being able to do real time monitoring from an extensive production plant has exclusively great benefits.