Oil Drilling Under the Northern Lights Entails Unexpected Challenges
|Energy-rich solar particles are hurled towards the Earth and generate beautiful northern lights, but also affect the instruments that determine the direction of the drill head. Illustration: Knut Steinnes|
|The geometric position of the drill head is calculated from the Earth’s gravitational and magnetic fields. The measurements are conducted using sensors in the drill equipment, approximately 10 m behind the drill head. Illustration: Knut Steinnes|
It is not simple to drill a straight well in the Barents Sea
In well drilling it is important to steer the drill head in the right direction, and a variety of instruments are used to control the process. The position of the drill is measured with sensors, that among other things keeps track of the vertical and horizontal positions, so-called "directional driven" drilling. The sensors that give us direction of the drill head are also driven by magnetism, and this is where challenges arise when drilling takes place in areas with much northern lights.
Leads drill out of position
The sensors in the drill are affected by the solar particles that are hurled toward Earth, and according to Edvardsen, there will be cases where the horizontal directional angle is affected 1-5 degrees in areas with strong northern lights.
Greater uncertainty further north
Edvardsen explains that in general, lateral uncertainty for directional drilling increases the further north you go. This is related to the physical properties of the Earth's magnetic field. Compared to wells in the North Sea, the inaccuracy for wells drilled in the Barents Sea is doubled. This means that a well with lateral uncertainty of 100 meters in the the North Sea, will have an uncertainty of 200 meters in the Barents Sea. In addition, drilling in the Barents Sea is affected by variations in the Earth's magnetic field caused by solar particles.
|The map shows the locations of magnetometers on shore. Those are central in correcting the instruments used for well drilling at sea. If compensating measures from these stations do not make it to the drilling site, this impede the drilling process. Illustration: Tromsø Geophysical laboratory.|
Variations in the Earth's magnetic field are calculated from measuring stations on shore
Edvardsen writes in his thesis that increased precision during drilling in the Barents Sea has been a focus area for both oil companies and suppliers in recent years.
-My work has led to proposed new methods and procedures where we correct for magnetic disturbances, says Edvardsen.
-These methods includes among others the use of measurement stations on shore. At these measurement stations fluctuations in Earth's magnethic field are recorded, which in turn can be used to correct measurements made in the wells.
Proposes measuring station on the ocean floor
During his doctoral work, Edvardsen has also observed that the distance to the land-based stations sometimes can be too far to be able to perform the necessary corrections. In his thesis, he recommends to set up measurement stations on the ocean floor when drilling wells in the middle of the Barents Sea. The drilling can the be carried out with greater precision.
|Inge Edvardsen graduated as Sivilingeniør from NTNU in 1999 and has been employed at Baker Hughes for 14 years. He defended his doctoral thesis at UiT on January 29th 2016. Photo: Private.|
Edvardsen completed an industrial PhD, which was a joint collaboration between the Department of Physics and Technology, UiT The Arctic University of Norway, Baker Hughes Norway and the Research Council of Norway.
The title of his thesis was: "Effects of Geomagnetic Disturbances on Offshore Magnetic Directional Wellbore Positioning in the Northern Auroral Zone." Edvardsen's PhD supervisors were Unni Pia Løvhaug, Department of Physics and Technology, Magnar Gullikstad Johnsen and Truls Lynne Hansen Tromsø Geophysical Observatory.