What do you use to drill for oil? There’s more than one answer to this question: Most companies rely on classic methods, where the borehole is made by a drill bit on the end of a drill pipe. In contrast, with casing drilling a large-diameter pipe known as casing is used. This method saves a considerable amount of time.
You drill a deep hole in the ground and with any luck, precious crude gushes out. This somewhat romantic fantasy scenario is gently corrected by Stefan Knehs; after all, the Drilling Manager is familiar with the reality. And it’s meticulously planned, extremely technical, and has little to do with luck. It also calls for a great deal of professionalism and methodology as there’s more than one way of drilling for crude.
Many paths lead to oil
Under the standard method, experts use a drill bit found on the end of a drill pipe. This is used to drill a deep hole. The so-called cuttings, i.e. the rock debris produced by the drill bit, is brought up to the surface and additional pipes are put in place to hold the borehole steady. The crude is them pumped out. “In casing drilling, casing is used for drilling as this simultaneously stabilizes the borehole and renders superfluous the addition of other pipes”, says Stefan Knehs on the advantages of this method.
Less time and enhanced safety with casing drilling
In addition to safety, the greatest advantage lies in the time saved. The larger diameter of the pipes enhances the stability of the borehole, facilitating faster drilling. As the pipe that is used for drilling remains in the hole, you save on having to remove the drilling paraphernalia – a hard and difficult job. This means that you can achieve your goal faster and more safely with this method.
When we tested casing drilling for the first time, we didn’t yet know what the consequences on later projects would be. But now, looking back, its hugely satisfying to go to work every day knowing that you have helped to develop a method that is safer and yields economic advantages.
Stefan Knehs, Drilling & Workover Manager, OMV Austria
Experience pays off
OMV has been drilling for oil in the Vienna Basin for more than 60 years. This not only means a lot of experience, but also a lot of comparative data. “We are one of the few companies worldwide to use casing drilling; OMV and OMV Petrom are in fact the only ones in Europe using it at the moment”, says Stefan Knehs. “On the one hand, the properties of the soil are significant in applying casing drilling – and in Marchfeld we have the best preconditions for that here. On the other hand, we have been producing here for many decades and so we can judge with great precision the advantages of one method over another”.
During the first attempt with casing drilling in 2009, the success was not immediately plain to see. And so it was put on the back burner. However, four years later the method was tested once again as the benefits of casing drilling are evident. And it finally worked on the second go. Stefan Knehs reminisces: “After certain adjustments and a learning curve, casing drilling emerged as an optimal variant and since then we have been primarily using this method in Austria when establishing drill sites for the production of crude oil and natural gas”.
You can find out more about casing drilling in the following video: