 |
| Titel |
Space weather effects on drilling accuracy in the North Sea |
| VerfasserIn |
S. J. Reay, W. Allen, O. Baillie, J. Bowe, E. Clarke, V. Lesur, S. Macmillan |
| Medientyp |
Artikel
|
| Sprache |
Englisch
|
| ISSN |
0992-7689
|
| Digitales Dokument |
URL |
| Erschienen |
In: Annales Geophysicae ; 23, no. 9 ; Nr. 23, no. 9 (2005-11-22), S.3081-3088 |
| Datensatznummer |
250015380
|
| Publikation (Nr.) |
 copernicus.org/angeo-23-3081-2005.pdf |
|
|
|
|
|
| Zusammenfassung |
| The oil industry uses geomagnetic field information to aid directional
drilling operations when drilling for oil and gas offshore. These operations
involve continuous monitoring of the azimuth and inclination of the well path
to ensure the target is reached and, for safety reasons, to avoid collisions
with existing wells. Although the most accurate method of achieving this is
through a gyroscopic survey, this can be time consuming and expensive. An
alternative method is a magnetic survey, where measurements while drilling
(MWD) are made along the well by magnetometers housed in a tool within the
drill string. These MWD magnetic surveys require estimates of the Earth's
magnetic field at the drilling location to correct the downhole magnetometer
readings. The most accurate corrections are obtained if all sources of the
Earth's magnetic field are considered. Estimates of the main field generated
in the core and the local crustal field can be obtained using mathematical
models derived from suitable data sets. In order to quantify the external
field, an analysis of UK observatory data from 1983 to 2004 has been carried
out. By accounting for the external field, the directional error associated
with estimated field values at a mid-latitude oil well (55° N) in
the North Sea is shown to be reduced by the order of 20%. This improvement
varies with latitude, local time, season and phase of the geomagnetic
activity cycle. By accounting for all sources of the field, using a technique
called Interpolation In-Field Referencing (IIFR), directional drillers have
access to data from a "virtual" magnetic observatory at the drill site. This
leads to an error reduction in positional accuracy that is close to matching
that of the gyroscopic survey method and provides a valuable independent
technique for quality control purposes. |
| |
|
| Teil von |
|
|
|
|
|
|
|
|