A new face drilling rig for narrow tunnels and ... - Advanced Mining

is to all intents and purposes sealed by the injection of
the drill mud, whether the drillstring is in place or not. To
this effect it is necessary to apply 1.5 times the calculated
hydrostatic pressure as a test pressure, as governed by
the depth reached at the drilling site.
The relevant personnel are required to attend special
training sessions (courses include ‘Principles of well
control’) at the Celle Drilling School in order that the
installed safety equipment can be deployed properly and
rapidly should an emergency arise.
Exploration drilling programme at K+S
KALI’s Zielitz potash mine
The Zielitz potash mine is one of six sites in Germany
where K+S KALI GmbH extracts potassium and
magnesium salts. These are used as feedstock for a
large range of potash, magnesium and sulphur fertilisers
and are also processed into products for technical,
commercial and pharmaceutical applications.
Zielitz started production in 1973 as the most recent
addition to the K+S KALI group. The mine employs a
workforce of some 1,700, making it one of the largest
employers in Saxony-Anhalt.
For 25 years potash mining at this site has focused
exclusively on the Zielitz 1 deposits. A roadway system
is underway getting established since 1998 to get access
to the mining concession Zielitz 2.
Military activities on the Colbitz-Letzlinger heath
have prevented this area of about 36 km² from being
surveyed by surface exploration drilling and geophysical
measurements. All tunnel developments completed to
date have been undertaken on the basis of and under
the cover of underground exploration work.
Issue 04 | 2010
TRANSFER OF TECHNOLOGY
In order to fill this gap in the exploration map and
provide back-up for its own survey activities K+S KALI
GmbH commissioned Thyssen Schachtbau GmbH in
early 2007 to carry out horizontal exploratory drillings
in the Zielitz 2 area of the mining concession. Starting
out from a number of drilling chambers the team drilled
a series of horizontal holes in two to four directions and
with a maximum length of 2,500 m.
The aim was to identify the location of the Ronnenberg
potash seam (K3RO) at predetermined intervals by using
a drilling programme comprising undulating holes and
deviated holes.
As the survey zone is located in an area of deposits
that is prone to salt migration it was also necessary to
explore the adjacent salt horizons in the roof and floor
(barrier layer identification). The interim results from
some 17,200 m of drilling were collated in October 2008
and yielded 28 seam exposures and 26 barrier layer
verifications.
The exploration programme is being carried out using
a universal drilling machine with an electro-hydraulic
drive (type HBR 201, supplied by Hütte) and an electrically
powered Triplex mud pump. The company has invested
heavily in this new drilling system with its various
attachments in order to ensure that the requirements
profile is being met to the full.
The drillers use the counterflush coring method with
saturated salt flushing. This highly effective and cost
efficient core drilling technique has already proved
successful in horizontal exploration work where special
performance requirements are involved. This system
differs from the wireline coring method in that reverse
mud flush circulation is used to facilitate uninterrupted
Schematic diagram of
borehole curvature
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