Improving the Accuracy of Directional Wellbore Surveying in the Norwegian Sea

Abstract

Time-dependent current fluctuations in the Earth's ionosphere cause inaccuracies in wellbore directional surveying. These inaccuracies increase at higher latitudes, and although monitoring and correction are possible, they become less valid as the distance between the monitoring site and the rigsite increases, which is a particular problem for offshore drillsites. The characteristics of the ionosphere currents indicate that the most favorable location for monitoring stations is on the same geomagnetic latitude as the drillsite. Such an arrangement has been used to monitor and correct directional surveys at the Haltenbanken area of the Norwegian Sea over a period of approximately 2 years. Haltenbanken is approximately 200 km west of the Norwegian coast at latitude 65 N, where magnetic-storm activity can have a significant effect on directional surveying. A monitoring station was set up on the coast at the same geomagnetic latitude as Haltenbanken. To test the idea that magnetic disturbances are similar along constant magnetic latitude, an additional monitoring station was established 200 km east of the main station. The data broadly confirmed the hypothesis, although isolated events were observed when this was not the case. The challenges of surveying at offshore sites north of 62 N latitude are probably greater than the oil and gas industry is accustomed to-but such challenges will become more significant if the Arctic Ocean is opened to drilling operations. The technique described in this paper may contribute to safer and more-productive offshore operations at high latitudes.

High-latitude crochet: solar-flare-induced magnetic disturbance independent from low-latitude crochet

“…To have a sufficient amount of variations with low activity for the calculation, while avoiding contamination of main field secular variation, the removal of the quiet levels is performed on 10 d of data centred on the day of interest. The uncertainty is estimated to be less than 10 nT (see Edvardsen et al, 2013, for more details).…”

Effects of substorm electrojet on declination along concurrent geomagnetic latitudes in the northern auroral zone

“…From a directional drilling perspective, a constant declination offset from the quiet level for several hours can have a devastating effect on the wellbore position and the result can be missed geological targets and anti-collision situations (Edvardsen et al 2014). In such cases, data on the geomagnetic variations at a nearby observatory or variometer should be used to monitor the situation, and if applicable, corrections should be made (Edvardsen et al 2013).…”

“…The two magnetograms show the deviations in the horizontal magnetic field component and the declination from quiet level. The quiet level in this study is calculated as per the procedure described in Edvardsen et al (2013). The substorm current wedge model Table 1.…”

Jim Dungey, The Open Magnetosphere, and Space Weather

“…The energy transferred into the magnetosphere by magnetic reconnection drives geomagnetic storms, during which the most rapid variations in the geomagnetic field cause strong geomagnetically induced currents that can degrade and damage power grids [ Kappenman , ], enhance corrosion of oil and gas pipelines [ Viljanen et al , ], and cause errors in magnetic guidance systems, such as those needed for safe oil and gas borehole drilling [ Edvardsen et al , ]. Magnetic reconnection also controls the near‐Earth energetic particle environment within which most satellites, astronauts and aircraft operate: it is central to the occurrence of solar flares and the release of coronal mass ejections (CMEs), and the shock fronts ahead of both these phenomena accelerate bursts of solar energetic particles [ Reames , ] that are damaging to both electronics systems and living organisms.…”