Shielding of Directional Magnetic Sensor Readings in a Measurement While Drilling Tool for Oil Well Positioning

Amundsen, Per Amund; Torkildsen, Torgeir; Saasen, Arild

doi:10.1115/1.2358151

Cited by 17 publications

(18 citation statements)

References 5 publications

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“…This shielding can cause azimuth errors of 1-2 degrees, and errors even five to ten times larger may occur for certain wellbore directions under unfavourable conditions (Wilson and Brooks 2001;Torkildsen et al 2004;Amundsen, Torkildsen, and Saasen 2006). Thus, magnetic contamination can reduce the borehole position accuracy sufficiently to reduce the probability of hitting the planned target.…”

Section: Introductionmentioning

confidence: 93%

Experimental Investigation of the Magnetic Shielding Effect of Mineral Powders in a Drilling Fluid

Ding

Datta

Saasen

et al. 2010

Particulate Science and Technology

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Magnetic contamination of the drilling fluid shields the Earth's magnetic field measured by the magnetic sensors, and may contribute significantly to errors in directional surveying of a wellbore. A series of laboratory measurements were performed to investigate such magnetic shielding effects. In the measurement, a single axis fluxgate magnetometer was immersed in model drilling fluids prepared by mixing powders of known magnetic properties (magnetite and pure iron) into a solution of xanthan gum in fresh water, whereafter the vertical component of the Earth's field inside the fluid was measured. It was found that the strong shielding effect of dry iron powder essentially vanished when was suspended in the drilling fluid. The magnetic shielding caused by magnetite, however, remained significant also in solution, showing a complex dynamical behaviour. Initially the magnetic field was significantly damped, and this shielding was found to increase further for the next hour or so, reaching a fairly sharp maximum. The shielding then started to decay slowly and irregularly again over the next few days.

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Section: Introductionmentioning

confidence: 93%

Experimental Investigation of the Magnetic Shielding Effect of Mineral Powders in a Drilling Fluid

Ding

Datta

Saasen

et al. 2010

Particulate Science and Technology

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“…Amundsen et al 4 model the magnetic field inside a susceptible fluid as a function of the external field and the geometry of the fluid volume. An idealized geometry is chosen: Two co-axial infinite long cylinders where the fluid is filled in the space between them, and the fluxgate magnetic sensors are located inside the inner one.…”

Section: Attenuation Of the Cross-axial Magnetic Field Intensity Derimentioning

confidence: 99%

“…The magnetic susceptibility for a material describes how it becomes magnetized by an external magnetic field 4 . Drilling fluids have mostly small positive susceptibility values, and are said to be paramagnetic.…”

Section: Introductionmentioning

confidence: 99%

Drilling Fluid Affects MWD Magnetic Azimuth and Wellbore Position

et al. 2004

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fax 01-972-952-9435. AbstractThe drilling fluid may degrade the accuracy of magnetic azimuth and borehole position significantly so that it complicates the drilling operation and reduces the possibility to hit the planned targets. As an example: Azimuth is distorted up to 5° because of the magnetic properties (susceptibility) of the drilling fluid; and the wellbore is displaced 50 meter in one of the analyzed survey sections.Survey data from 30 well sections in the North Sea and the Norwegian Ocean are analyzed in order to see whether the weight material in the drilling fluid may affect the magnetic characteristics for the drilling fluid. The cross-axial magnetic field intensity is attenuated more when applying ilmenite instead of barite as weight material. Another significant finding is that the attenuation is stronger in 12 ¼" sections than in 17 ½" and 8 ½" sections.Laboratory experiments also indicate that drilling fluids with barite are less susceptible than those with ilmenite, and that fresh fluids are more favourable than used fluids. Attenuation factors for cross-axial magnetic components, which are derived from laboratory measurements and a simplified model of the downhole conditions, become much lower than those derived directly from the survey data. This contradiction is explained by some physical and operational conditions.Guidelines have been established for how to control, reduce and eliminate the negative effect on the wellbore positions. The precautions and actions, which are presented, are dependent on the composition of the drilling fluid, the drilling operation, the wellbore directions, the magnetic interference sources, the accuracy of the geomagnetic reference field and the requirements for wellbore position accuracy and reliability.The ultimate method for getting around this problem is to measure azimuth with a gyroscopic tool. However, multistation analysis and corrections of magnetic survey data is also a satisfactory solution when certain operational and geometrical requirements are met.

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“…This section summarizes the work done by Amundsen et al (2005) [1]. A shorter version of the paper is presented by Amundsen et al (2006) [8].…”

Section: Basic Concepts Of Magnetic Fieldsmentioning

confidence: 99%

“…A shorter version of the paper is presented by Amundsen et al (2006) [8]. The magnetic field of the Earth is present at all times and during drilling it is used to navigate the drill-bit towards the pre-set target using the Measuring While Drilling (MWD) directional tool as steering assembly.…”

Section: Basic Concepts Of Magnetic Fieldsmentioning

confidence: 99%

Ditch Magnet Performance

Strømø

Saasen

Hodne

et al. 2017

Volume 8: Polar and Arctic Sciences and Technology; Petroleum Technology

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Magnetic shielding of the Measurement While Drilling (MWD) directional tools and damages to mud pumps, down-hole tools and casing/drill-pipe and difficulties in understanding logging results are some of the main problems caused by steel and magnetic contaminated drilling fluids. In order to have these problems significantly reduced, all the magnetic contaminants should ideally be removed from the drilling fluid by the use of ditch magnets. Hence, the magnets and their ability to remove magnetic waste from the drilling fluid was evaluated by field evaluations. Data from a field test of a new ditch magnet system where all the drilling fluid is forced to flow into an area with a strong magnetic fields have been compared with data from an operation with a traditional ditch magnet system in order to see if there are any significant differences in the total amount of magnetic waste material collected from the two systems. It is shown how drilling length, inclination and casing size may affect the production of magnetic debris entering the drilling fluid, and hence, show the well construction dependence of the ditch magnet performance.

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Shielding of Directional Magnetic Sensor Readings in a Measurement While Drilling Tool for Oil Well Positioning

Cited by 17 publications

References 5 publications

Experimental Investigation of the Magnetic Shielding Effect of Mineral Powders in a Drilling Fluid

Experimental Investigation of the Magnetic Shielding Effect of Mineral Powders in a Drilling Fluid

Drilling Fluid Affects MWD Magnetic Azimuth and Wellbore Position

Ditch Magnet Performance

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