Horizontal drilling: Lateral approach to straight lines
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This is a highly promising reservoir. At least that’s what those in the know say – the geologists who specialize in what lies beneath the earth. But directly on the surface above this deposit lies a village. Now the task is to find a way of getting to the reservoir without impacting the village. Carefully and yet in a way that is still economically feasible. This calls for lateral thinkers!
“The classic approach is to drill down vertically into a reservoir. When that’s not possible, we have the option of horizontal drilling”, says Neal Whatson, OMV Head of Well Engineering. For example, the conditions of the terrain sometimes don’t allow a drilling rig to be erected on site. The horizontal drilling technique is a simple way of getting to the desired target spot underground. And it doesn’t matter whether your well is on land or offshore.
Broader than tall
But the terrain on the surface of the earth is not the decisive factor when choosing the drilling method, the conditions underground also have a significant impact. Sometimes the geological stratum in which the crude oil or natural gas is located is suitably extensive – i.e. wide and large – but not that thick. Therefore if you drill a classic vertical well, you will only “access” a couple of meters of the oil bearing stratum. The well would hardly be profitable. By using the horizontal drilling method, you can plan better for challenges such as flow resistance or flow rate or even use these to your advantage. The result is higher-yield production with less wells.
I would go as far to say that we are among the world champions when it comes to horizontal drilling. Think of Suplac, for example, a development in Romania in 2011. We set new world records with three horizontal wells at vertical depths of less than 200 m. More recently we also set a new offshore record in Norway with the Wisting well.
Neal Whatson, Head of Well Engineering at OMV
Drilling round corners
How on earth can you drill round a corner? It’s certainly not possible with traditional drilling methods where the entire drill pipe rotates. But then how? With a downhole motor that drives the drill bit and an integrated elbow, or with rotary steerable systems (RSS) which points the drill bit in the desired direction, in effect you can drill round corners. “And because we can’t take a look underground, downhole measuring devices do that for us. They give us information about the direction and inclination of the bit. Then we have the option aboveground of adjusting the well trajectory as we drill”, says Neal Whatson.
This type of drilling is especially impressive when conducted in challenging surroundings such as the Barents Sea. With Wisting Central II we even set a new drilling record – the shallowest horizontal offshore drilling with a floating rig. That sounds impressive, and it is. But why not take a look for yourself:
Factbox: Wisting Central II
The Wisting Central II well is the first horizontal appraisal well in the Barents Sea and sets a new drilling record; it is the shallowest horizontal offshore well drilled from a floating drilling facility. Water depth at Wisting is 402 meters. The well started vertically and was successfully steered into a horizontal orientation within a 250 meters depth interval. The total well length is 2,354 meters and the horizontal section measures 1,402 meters. Advanced data collection and geophysical survey was conducted through the entire horizontal phase. The well was spudded on January 15, 2016, by the semisubmersible rig Transocean Spitsbergen and the well test was finalized end of March 2016.