AAPG Methods in Exploration No. 14, Chapter 16: Geosteering
of High-angle Wells Using Heavy-mineral Analysis: The Clair Field, West of Shetland, U.K. , by A. C. Morton, P. J. Spicer, and D. Ewen, Pages 249 - 260
from:
AAPG Methods in Exploration No.
14: Horizontal Wells: Focus on the Reservoir, Edited
by T. R. Carr, E. P. Mason, and C. T. Feazel
Copyright 
2003 by The American Association of Petroleum Geologists. All rights
reserved.
Chapter 16
Geosteering of High-angle Wells Using Heavy-mineral Analysis: The Clair Field, West
of Shetland, U.K.
A. C. Morton1
HM Research Associates
Woodhouse Eaves
Leicestershire, U.K.
P. J. Spicer
Ryton Exploration
GeoScience Ltd.
Barnet, Hertfordshire, U.K.
D. Ewen
BP Exploration
Aberdeen, U.K.
1Also with the Department of Geology and Petroleum Geology,
University of Aberdeen, Aberdeen, U.K.
ABSTRACT
Conventionally, a combination of biostratigraphy, logging-while-drilling (LWD) data,
and routine cuttings description is used to monitor continually the geology encountered
during drilling of high-angle wells. However, the biostratigraphic component of the
geosteering tool kit cannot be used if there is insufficient diversity of microfossils in
the sequence to be drilled. In such circumstances, alternative, less conventional
geosteering methods can be used. This paper presents the application of one such approach,
heavy-mineral analysis (HMA), in monitoring high-angle wells in the Clair field, west of
Shetland, U.K. The reservoir sequence in the Clair field comprises Devonian-Carboniferous
nonmarine fluvial and eolian sandstones that lack a continuous, diverse suite of
palynomorphs. Consequently, there is no high-resolution biostratigraphic framework for
reservoir correlation. By contrast, heavy minerals occur throughout the sequence and
therefore offer a potential for correlation and discrimination of different sandstone
units.
