corrosive species and scaling in wells at olkaria ... - Orkustofnun

3. SAMPLING AND ANALYSIS
3.1 Sample collection
At Reykjanes, Svartsengi and Nesjavellir,and other Icelandic fields both steam and water are collected
at the same pressure using a Webre separator.
At Olkaria various
methods have been
applied to collect
samples of water and
steam from the wetsteam
well discharges.
Some of these methods
are described by Ellis
and Mahon (1977) and
Arnόrsson et al.
(2000). One of the
methods involves the
use of a Webre
separator, which is
connected to a twophase
pipeline that
conveys the total
discharge to an
atmospheric silencer
(Figure 8).
By this method
sampling involves the
collection of steam samples
under pressure from the
Webre separator and water
from the weirbox. Steam
samples collected in this
way are mostly from the
wells that are being
discharge tested or
exploration wells and a
number of production wells
in the Olkaria East
production field that share a
common separator station.
In the Olkaria North East
Field which produces steam
for the Olkaria II power
plant sampling of steam and
water will be carried out by
FIGURE 8: Steam is collected from a Webre separator on a two-phase
pipeline upstream from the atmospheric silencer and water from the
weirbox, a part of the steam (X w-a ) discharged from the atmospheric
silencer is not sampled, i.e. the steam which forms by depressurisation
boiling from the pressure in Webre separator to atmosphere
FIGURE 9: Steam is collected from the steam separator and water
from the weirbox, the steam (X s-a ) discharged from the atmospheric
silencer is not sampled. This steam forms by depressurisation
boiling from pressure in the steam separator
to atmospheric pressure
the use of a Webre separator. For production wells in the Olkaria East Production Field, steam
samples were collected from the steam line downstream of the wellhead separator using a stainless
steel tubing (Figure 9).
Water samples were collected from the weirbox. A fraction of the discharge is not sampled when the
water and steam samples are collected at different pressures as explained in Figs. 8 and 9. As
explained in section 5.2 below, it is assumed when calculating aquifer water composition that the
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