Direction Drilling Measurement Errors Caused by Drilling Fluid Constituents

2016 ◽  
Author(s):  
Giorgio Pattarini ◽  
Sheldon Rawlins ◽  
Arild Saasen ◽  
Per Amund Amundsen ◽  
Benny Poedjono
Keyword(s):  
Magnetic Properties ◽  
Magnetic Materials ◽  
Geomagnetic Field ◽  
Measurement Errors ◽  
Drilling Fluid ◽  
Shielding Effect ◽  
Measurement While Drilling ◽  
Drilling Muds ◽  
Shielding Effects

Materials in drilling muds are known to sometimes distort the geomagnetic field at the location of the Measurement While Drilling (MWD) tool magnetometers that are used to measure the azimuth of well path. This distortion or shielding effect can contribute to substantial errors in determination of azimuth while drilling deviated wells and with significant well displacements, these errors may result in missing the target of a long deviated section in the range of 1–200m; and thus impact on the overall productivity expectation of the well. The article describes significant shielding effects observed while drilling long wells. The criteria for acceptance of the surveys were not met and resultantly, an alternative survey source had to be obtained with resulted in increased cost and time to the client. A number of measures were implemented to eliminate this shielding effect. The effects of drilling fluid contamination by magnetic materials are calculated, and a method to evaluate the magnetic properties of the drilling fluid is proposed. The effect of taking measurements with the pumps on versus off is quantified.

The Shielding Effect of Drilling Fluids on Measurement While Drilling Tool Downhole Compasses—The Effect of Drilling Fluid Composition, Contaminants, and Rheology

2016 ◽  
Vol 138 (5) ◽  
Author(s):  
Arild Saasen ◽  
Songxiong Ding ◽  
Per Amund Amundsen ◽  
Kristoffer Tellefsen
Keyword(s):  
Drilling Fluid ◽  
Shielding Effect ◽  
Magnetic Shielding ◽  
Drilling Fluids ◽  
Fluid Composition ◽  
Iron Ions ◽  
Drilling Tool ◽  
Measurement While Drilling ◽  
Drilling Site ◽  
Wear Products

Materials such as added clays, weight materials, drill solids, and metallic wear products in the drilling fluid are known to distort the geomagnetic field at the location of the measurement while drilling (MWD) tool magnetometers that are used to measure the direction of well path. This distortion contributes to substantial errors in determination of azimuth while drilling deviated wells. These errors may result in missing the target of a long deviated 12 ¼ in. section in the range of 1–200 m, representing a significant cost to be mitigated. The error becomes even more pronounced if drilling occurs in arctic regions close to the magnetic north pole (or south pole). The effect on the magnetometer readings is obviously linked to the kinds and amounts of magnetic materials in the drilling fluid. The problem has recently been studied by laboratory experiments and analyses of downhole survey data. A series of experiments has been carried out to understand how some drilling fluid additives relate to the magnetic distortion. Experiments with free iron ions show that presence of iron ions does not contribute to magnetic distortion, while experiments with bentonite-based fluids show a strong effect of bentonite on magnetic shielding. Albeit earlier measurements showing a strong dependency of the content of organophilic clay, clean laboratory prepared oil-based drilling fluids show no increased shielding when adding organophilic hectorite clays. The anticipated difference between these two cases is outlined in the paper. When eroded steel from an offshore drilling site is added into the oil-based drilling fluid, it is found that these swarf and steel fines significantly increase the magnetic shielding of the drilling fluid. The paper outlines how the drilling direction may be distorted by the presence of these additives and contaminants and how this relates to the rheological properties of the drilling fluid.

The Shielding Effect of Drilling Fluids on MWD Downhole Compasses: The Effect of Drilling Fluid Composition, Contaminants and Rheology

2014 ◽  
Author(s):  
Arild Saasen ◽  
Songxiong Ding ◽  
Per Amund Amundsen ◽  
Kristoffer Tellefsen
Keyword(s):  
Drilling Fluid ◽  
Shielding Effect ◽  
Magnetic Shielding ◽  
Drilling Fluids ◽  
Fluid Composition ◽  
Iron Ions ◽  
Arctic Regions ◽  
Measurement While Drilling ◽  
Drilling Site ◽  
Wear Products

Materials such as added clays, weight materials, drill solids and metalic wear products in the drilling fluid are known to distort the geomagnetic field at the location of the Measurement While Drilling (MWD) tool magnetometers that are used to measure the direction of well path. This distortion contributes to substantial errors in determination of azimuth while drilling deviated wells. These errors may result in missing the target of a long deviated 12 ¼″ section in the range of 1–200m; representing a significant cost to be mitigated. The error becomes even more pronounced if drilling occurs in arctic regions close to the magnetic North Pole (or South Pole). The effect on the magnetometer readings is obviously linked to the kinds and amounts of magnetic materials in the drilling fluid. The problem has recently been studied by laboratory experiments and analyses of downhole survey data. A series of experiments has been carried out to understand how some drilling fluid additives relate to the magnetic distortion. Experiments with free iron ions show that presence of iron ions does not contribute to magnetic distortion; while experiments with bentonite-based fluids show a strong effect of bentonite on magnetic shielding. Albeit earlier measurements showing a strong dependency of the content of organophilic clay, clean laboratory prepared oil-based drilling fluids show no increased shielding when adding organophilic hectorite clays. The anticipated difference between these two cases is outlined in the paper. When eroded steel from an offshore drilling site is added into the oil-based drilling fluid, it is found that these swarf and steel fines significantly increase the magnetic shielding of the drilling fluid. The paper outlines how the drilling direction may be distorted by the presence of these additives and contaminants and how this relates to the rheological properties of the drilling fluid.

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

2005 ◽  
Vol 128 (4) ◽  
pp. 343-345 ◽  
Author(s):  
Per A. Amundsen ◽  
Torgeir Torkildsen ◽  
Arild Saasen
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Magnetic Materials ◽  
Explicit Solution ◽  
Drilling Fluid ◽  
Magnetic Sensor ◽  
Magnetic Sensors ◽  
Oil Well ◽  
Drilling Tool ◽  
Measurement While Drilling

Magnetic materials in the drilling fluid used for drilling a petroleum well can significantly shield the Earth’s magnetic field as measured by magnetic sensors inside the drilling pipe. This has been shown to sometimes cause significant errors in the accuracy of borehole positioning using magnetic surveying. In this paper we present a physical approach for correcting the measured magnetic fields for such shielding. An explicit solution of the shielding problem is derived for the simplest case of a magnetic sensor on the axis of the borehole.

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