Targeting Challenges in Northern Areas Due to Degradation of Wellbore Positioning Accuracy

Bang, Jon; Torkildsen, Torgeir; Bruun, Bjoern T.; Havardstein, Stein Tjelta

doi:10.2118/119661-ms

Cited by 12 publications

(4 citation statements)

References 2 publications

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“…In addition, some MWD gyroscope systems can be programmed to perform surveys from TD to surface when tripping out of hole and produce an overlapping data set that can be used for further quality-control improvement. It should be noted that the accuracy of any gyroscope system decreases with increasing geographical latitude, as described by Bang et al (2009).…”

Section: Discussionmentioning

confidence: 99%

“…The DSI affects b z and normally constitutes the major uncertainty in the reading. Bang et al (2009) evaluated the accuracy of both magnetic and gyroscopic directional surveys in northern areas and the effects of degraded azimuth accuracy upon wellbore design. They concluded that the lateral uncertainty increases by a factor of approximately two when moving from North Sea to Barents Sea latitudes and emphasized the need for optimized surveying programs and practices.…”

Section: Introductionmentioning

confidence: 99%

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Improving the Accuracy and Reliability of MWD/Magnetic-Wellbore-Directional Surveying in the Barents Sea

Edvardsen

Nyrnes

Johnsen

et al. 2014

SPE Drilling &Amp; Completion

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The years ahead will see increased petroleum-related activity in the Barents Sea, with operations far off the coast of Norway.The region is at high geomagnetic latitude in the auroral zone, and therefore, directional drilling by use of magnetic reference will experience enlarged azimuth uncertainty compared with operations in the Norwegian and North Seas. Two main contributors to azimuth uncertainty are magnetic disturbances from electric currents in the ionosphere and axial magnetic interference from the drillstring. The former is more frequent in the Barents Sea than farther south, and the effect of the latter is increased because of diminished value of the magnetic horizontal component. Wellbore directional surveying for operations on the continental shelf in the North Sea and the Norwegian Sea rely on wellestablished procedures for near-real-time magnetic monitoring by use of onshore magnetic-reference stations. The different land and sea configuration, distant offshore oil and gas fields, higher geomagnetic latitude, and different behavior of the magnetic field require the procedures to be reassessed before being applied to the Barents Sea. To reduce drilling delays, procedures must be implemented to enable efficient management of magnetic disturbances. In some areas of the Barents Sea, the management requires new equipment to be developed and tested before drilling, such as seabed magnetometer stations. One simple way to reduce drillstring interference is increasing the amount of nonmagnetic steel in the bottomhole assembly (BHA). To maintain azimuth uncertainty at an acceptable level in northern areas, it is crucial that wellbore-directional-surveying requirements are given high priority and considered early during well planning. During the development phase of an oil and gas field, the planned wells must be assigned adequate positional-uncertainty models and, if possible, be designed in a direction that minimizes the wellbore directional uncertainty.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Improving the Accuracy and Reliability of MWD/Magnetic-Wellbore-Directional Surveying in the Barents Sea

Edvardsen

Nyrnes

Johnsen

et al. 2014

SPE Drilling &Amp; Completion

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show abstract

“…The importance of the earth's magnetic field as a reference for directional drilling has been described in several earlier papers (Zijsling and Wilson 1989;Russell et al 1995;Williamson et al 1998;Bang et al 2009). The geomagnetic reference field B is commonly described as a vector sum of the main field B m , the crustal field B c , and the disturbance field B d :…”

Section: The Earth's Magnetic Fieldmentioning

confidence: 99%

Improving the Accuracy of Directional Wellbore Surveying in the Norwegian Sea

Edvardsen

Hansen

Gjertsen

et al. 2013

SPE Drilling &Amp; Completion

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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.

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“…It is well known that the accuracy of the gyro is reduced the closer to the geographic North Pole (or South Pole) that the well is drilled as the earth's effects from rotation is less [1]. Similarly, the accuracy of magnetic directional measurements, all else being equal, is reduced the closer to the magnetic Poles a well is drilled as the horizontal field is smaller [2].…”

Section: Introductionmentioning

confidence: 99%

Efficient Removal of Magnetic Contamination From Drilling Fluids: The Effect on Directional Drilling

Saasen

Poedjono

Ånesbug³

et al. 2021

Journal of Energy Resources Technology

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Magnetic debris in a drilling fluid have a significant influence on the ability of the drilling fluid to maintain its function. Down hole logging can suffer from poor signal to noise ratios. Directional drilling in areas close to the magnetic North Pole, such as in the Barents Sea, Northern Canada, or Russia, can suffer because of magnetic contamination in the drilling fluid. Magnetic particles in the drilling fluid introduce additional errors to the magnetic surveying compared to those normally included in the ellipsoid of uncertainty calculation. On many offshore drilling rigs, there are mounted ditch magnets to remove metallic swarf from the drilling fluid. These magnets normally only remove the coarser swarf. In this project, we use a combination of strong magnets and flow directors to significantly improve the performance of the ditch magnets. This combination, together with proper routines for cleaning the ditch magnets, significantly helps to clean the drilling fluid. Through the combined use of flow directors and ditch magnets, it was possible to extract more than five times as much magnetic contamination from the drilling fluid as normal compared with other proper ditch magnet systems. This is verified by comparing the ditch magnet efficiencies from two drilling rigs drilling extended reach drilling (ERD) wells in the North Sea area. In this paper, it is discussed how the accuracy of directional drilling and well position effected by various interferences can be improved by the use of a drilling fluid with minimal effect to the measurement while drilling (MWD) measurement.

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Targeting Challenges in Northern Areas Due to Degradation of Wellbore Positioning Accuracy

Cited by 12 publications

References 2 publications

Improving the Accuracy and Reliability of MWD/Magnetic-Wellbore-Directional Surveying in the Barents Sea

Improving the Accuracy and Reliability of MWD/Magnetic-Wellbore-Directional Surveying in the Barents Sea

Improving the Accuracy of Directional Wellbore Surveying in the Norwegian Sea

Efficient Removal of Magnetic Contamination From Drilling Fluids: The Effect on Directional Drilling

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