Ditch Magnet Performance

Strømø, Kjartan Moe; Saasen, Arild; Hodne, Helge; Pallin, Jan Egil; Aaker, Gudmund

doi:10.1115/omae2017-61026

Cited by 6 publications

(1 citation statement)

References 13 publications

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“…ditch magnet system removes significantly more magnetic contamination from the drilling fluid than any other ditch magnet systems[4,15,16]. The reason for this is the flow position system where the drilling fluid volumes are forced to flow closer to the strong magnetic field.…”

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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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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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Ditch Magnet Removal of Steel Particles

Pattarini

Strømø²,

Saasen

et al. 2017

Day 1 Wed, April 05, 2017

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Drilling fluids contain magnetic contaminations that negatively affect Measurement While Drilling directional tools and causes damage to the equipment in contact with the fluid. The effect is relevant while drilling long deviated wells. Ditch magnets are routinely installed in the fluid system to remove magnetic particles while drilling, with the purpose of protecting the Shale Shaker screens from large metallic debris, serve as monitoring tool to detect troubles in the drilling operations and clean the fluid from magnetic particles. In this paper we describe field data for the operation and efficiency of the ditch magnets. An extensive set of samples of drilling fluid and of ditch magnets debris have been taken during offshore operations and have been brought onshore for detailed investigations. The material extracted has been assessed as constituted mainly by steel swarfs and steel fines. The magnetic materials still present in the used drilling fluid have been extracted and quantified by a novel method that provide higher extraction rates and better accuracy than the methods currently employed in the industry, allowing to assess the actual content of magnetic contaminant. The magnetic susceptibility of the fluid has been measured and compared with values predicted for a known concentration of magnetic contaminants, allowing for the evaluation of the bias induced by them on the magnetometers of the MWD tools employed. The capability of ditch magnets to remove the magnetic contaminants from fluid is quantified and compared with other available methods, like gravity separation, with special focus on the removal of magnetic particles in the range of few microns. Operational details and current issues in the deployment of ditch magnets are reviewed, and the most viable directions for improvement are briefly discussed.

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Best Practices and Recommendations for Magnetic Directional Surveying in the Barents Sea

Edvardsen

Nyrnes

Johnsen

et al. 2019

Day 1 Tue, May 14, 2019

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In the coming years, several oil and gas fields in the Barents Sea will be developed. The Barents Sea is located between 71-74° latitude and is a part of the Arctic Ocean. At such high latitudes, surveying with magnetic Measurement-while-drilling (MWD) and gyro survey instruments result in almost twice the azimuth uncertainties of the North Sea latitudes. Magnetic MWD is the most common survey method, mainly due to low cost and time consumption to perform a measurement. However, the main drawback with magnetic MWD survey instruments is the sensitivity to external magnetic fields resulting from magnetic components in the bottom hole assembly (BHA), magnetic particles in drilling fluids, and fluctuations in the Earth's magnetic field. The Barents Sea is in the auroral zone where the largest geomagnetic field disturbances are experienced. Consequently, achieving accurate reference field parameters for MWD surveying is challenging. Different methods exist to maintain an acceptable quality of magnetic survey data at high latitudes. One approach is to isolate the magnetometer sensors from external magnetic interference and apply uncorrected azimuth calculation. This is advantageous because uncorrected azimuth is less sensitive to external field disturbances than corrected azimuth achieved by drill string interference (DSI) correction or multi-station analysis (MSA). For offshore sites, limitations exist for using geomagnetic reference data from land-based monitoring stations to correct MWD data. Large azimuth uncertainties result in major lateral wellbore position uncertainties and give less room for blunders and gross survey errors when high accuracy is required. Consequently, it is vital to minimize the effects of external error sources. Several downsides of large position uncertainties exist, such as increased distance between wells to avoid collisions and decreased chance of hitting geological targets. The combined effect of external error sources is complex and in specific cases certain error sources cannot be detected using conventional quality control procedures. In this paper, recommendations to overcome the above-mentioned challenges will be presented.

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Ditch Magnet Performance

Cited by 6 publications

References 13 publications

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

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

Ditch Magnet Removal of Steel Particles

Best Practices and Recommendations for Magnetic Directional Surveying in the Barents Sea

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