Producing Oil & Gas onshore From primary recovery to abandonment
Once crude oil or natural gas has been discovered, it should, of course, be produced. To do so, first of all a well is necessary. Beneath the surface both these natural resources have a much higher pressure than at surface level. Once the reservoir has been drilled into, the oil and gas automatically take the path of least resistance – i.e., through the well to the surface. However, over time and as production increases, this pressure starts to fall off.
Natural gas can find its way to the production well much more easily than crude oil. The natural gas is initially fluid because of the high pressure. When the pressure declines, the gas becomes gaseous and thus very mobile. Up to 80 percent of the gas in a natural gas reservoir can be produced this way.
For crude oil, on the other hand, technical tools are necessary as soon as the pressure no longer drives the oil to the surface. Crude oil production can be divided into three phases. So far, on average it has only been possible to recover about a third of the oil in place. But with the help of modern technology and constant advances to production techniques, this boundary can now be overcome.
We do not only explain the three phases of oil production, but also tell you the stories of three generations of employees who have experienced the challenges of each phase of oil production in Emlichheim first hand.
Phase One When the oil flows almost by itself
In the first phase of production – called primary production – barely any additional tools are necessary for recovering the oil and gas: at first the hydrocarbons flow towards the surface naturally because of the natural reservoir pressure. This pressure is created by the water weight contained in the pores of the rock strata, also known as hydraulic pressure. When the hydrocarbons flow out as production starts, the pressure within the reservoir also falls off and the water behind starts flowing too.
While natural gas can still be produced when the pressure is declining, oil has to be aided along the way, for example with artificial lift techniques. With gas lift for example natural gas is pumped back into the borehole, which decreases the weight of the oil column in the well and the valuable natural resource can rise to the surface with the gas – just as with a straw in a lemonade bottle. When that no longer helps, it’s time for the downhole pumps: this is when tools such as the well-known nodding donkey pumps become responsible for transporting the oil to the surface. About 15 to 20 percent of the oil can be recoverd from the reservoir this way.
Generation One Jan Wilm van der Veen: Always a good neighbor
When Jan Wilm van der Veen was born in 1947, it was just at the time when crude oil production in Emlichheim on the German-Dutch border had really taken off. The horse-head pumps were nodding away right on his doorstep, Wintershall was his nearest neighbor. “We even got our electricity from them,” the Dutchman, who only speaks German, remembers.
Wintershall had a good deal on its electricity and made sure its immediate neighbors benefitted from this too. It was probably this proximity to Wintershall that led van der Veen to begin working for the company in 1973 as a member of the workover crew. His job was to unscrew and load the piping at the production wells. Later, as a crane operator he also operated the so-called “winch”, which was used to carry out repairs to the wells.
Van der Veen has such a close relationship with the winch that his colleagues set it up in his yard to mark his 25 years of service to the company.
This likeable pensioner always enjoyed his job – even though it involved tough physical labor: “Technology wasn’t as far advanced then as it is now. When, for example, there was a defect on an underground transport pipeline, we would dig down ourselves with two or three men to unearth it. That usually took the whole day.”
Phase Two More oil with water
When the primary production methods are no longer sufficient to produce the crude oil, production enters the second phase, called secondary production. One form of this, for example, is pumping water into the reservoir via one or more wells at the edge of the oil field. This raises the pressure in the reservoir and the oil starts flowing to the well again, which allows another 15 – 20 percent of the oil to be recovered. The following diagram shows how the second production phase works.
Generation Two Gerd Oldekamp: It’s all about the right dose
Like his former colleague Jan Wilm, Gerd Oldekamp is also well-acquainted with the winch. The trained carpenter began at Wintershall in 1982 where he trained as a crane operator. He witnessed the early days of steam flooding in Emlichheim in the so-called “Scholle 6”. With the steam flooding technique, steam at a temperature of 300 degrees is pumped into the reservoir to warm up the viscous oil, thereby making it runnier – and easier to recover.
Thanks to this technology, Wintershall has been able to keep oil production in Emlichheim at a constantly high level since the 1980’s. “We learned a great deal in the first few years of steam flooding,” Oldekamp recalls. “At the beginning we used a lot of steam because we thought the more the better. But gradually we got the hang of it and then we started dosing the steam injections more effectively.”
Oldekamp still operates the winch to this day. He is responsible for completing new wells: in other words, he refits them so that they can produce oil or replaces the drill pipes of older wells. This very conscientious expert also checks, alongside his colleagues working in the three-shift system, that everything is OK in Scholle 6. “The plants and pipes are all remote monitored round the clock, but we still prefer to check ourselves”, he says smiling.
Phase Three Oil production with sophisticated techniques
After a certain time, flooding the reservoir with water no longer helps. Since the water always takes the path of least resistance, some parts of the reservoir are by-passed. In addition, the water mostly transports the light, runny oil and the thick, viscous oil remains trapped. But in order to keep producing, special advanced techniques are used in the third production phase – called tertiary production: so-called Enhanced Oil Recovery (EOR) techniques for example make the viscous oil runnier, which allows another approx. 10 to 20 percent to be recovered from the reservoir.
One example of EOR is steam flooding: with this technique, steam is injected into the reservoir at high pressure. This warms the viscous oil and makes it runnier so that it flows to the production well more easily. Another method of enhanced oil recovery involves the use of polymers, which are primarily used as thickening agents. The polymers thicken the injection water so that it no longer flows past the oil, but pushes the oil up to the surface. In addition, Wintershall is currently researching a new possibility of improving oil production in an environmentally friendly way: with the help of a natural polymer produced by a natural fungus.
Generation Three Niko Hauschke: Getting oil
Niko Hauschke knows the steam flooding facility like the back of his hand. The young man comes from the area around Emlichheim, he’s a local born and bred. At Wintershall he is in charge of starting up and turning off the boilers that generate the steam needed for the steam flooding. Inspecting and servicing the boilers are also part of his duties as plant operator. To qualify for this job he acquired the boiler attendant certificate specially.
Together with his colleagues, the trained energy systems electronic engineer makes sure that the facility is operational at all times and runs without a hitch at full load too. Wintershall currently injects steam into nine injection wells in Emlichheim, and additional wells are planned.
So Niko Hauschke will be needed for a long time to come. He’s happy about that: “I could do this job until I retire. The work is wide-ranging, no two days are the same. Of course, at some point it becomes routine to a certain degree. But that is really good for some things, for example if there’s a technical challenge you know exactly what you have to do.” And although the technology today is much more sophisticated than it used to be and many things happen automatically, Hauschke himself has to roll up his sleeves: “It’s not like I just sit here and press a few buttons,” he says laughing. “There’s still a lot of handwork involved.”
Production in extreme conditions
We demonstrate every day that Wintershall can produce oil and gas even in extremely harsh conditions, for example in Novy Urengoy in Russia. Here, at one of the most remote locations imaginable, Wintershall’s experts overcome extreme climactic and geological challenges. The film shows how production just 35 kilometers from the Arctic Circle works.
We care for the environment Highest standards for safety
In all its activities, Wintershall places great importance on to ensuring that the production of oil and gas are conducted in harmony with nature and mankind. Our equipment and plants conform with the highest safety standards and are at the cutting edge of technology.
To secure the borehole, it is sealed with a so-called “Christmas tree”, also known as “X-Tree”. The tree is an assembly of valves and pressure gauges that prevents oil and gas from escaping. A liquid-tight seal made of asphalt would catch any liquids that escaped onto the well site and channel them into a collection tank. This way, the fluids cannot enter the environment. They are then disposed of in the correct manner.
However, it’s not just oil that rises to the surface during oil production. Saline reservoir water and associated gas are also transported to the surface. A so-called separator separates these materials from the crude oil. The crude oil is transported to the refinery where it is then processed; the reservoir water is collected in a central tank and then injected back into the oil field. Wintershall recycles the associated gas – which in most places round the world is simply flared – thus setting an example of responsible and sustainable management of resources and the environment. Instead of destroying valuable resources and emitting large quantities of greenhouse gases, we generate electricity, heat and steam from the gas.
Final stage Abandoning the well site
When a production well is no longer producing, Wintershall starts abandoning the well site: the plants and equipment needed for production are dismantled, the borehole is plugged with cement and sealed off. Hence, no liquids can leak into the surrounding rock layers once production has come to an end. The surface around the well site is then restored to its natural state, and afterwards it looks exactly the same as it did before the drilling. It is also possible to use the land as farmland again.