8. Field Guide Olkaria Oserian Domes 150310
Transcript of 8. Field Guide Olkaria Oserian Domes 150310
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Geothermal DevelopmentCompany, Kenya
Kenya ElectricityGenerating Company
Ministry of Energy,Kenya
African UnionFederal Institute forGeosciences and
Natural Resources,Germany
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FIELD ITINERARY
TIME ACTIVITY
07:00 hrs Delegates leave Nairobi Sarova Panafric Hotel
08:00-08:30 hrs STOP 1: Great Rift Valley View point
10:00-10:30 hrs STOP 2: Olkaria II - Tea and refreshments
10:30-11:00 hrs Tour of Olkaria II power plant
11:00-12:00 hrs STOP 3: Oserian greenhouse tour
12:00-13:00 hrs STOP 4: Rig and a discharging well
13:30-14:30 hrs Lunch Break
14:30-15:00 hrs STOP 5: Maasai Cultural Center
15:00 hrs Departure through Elsa gate (Site seeing)
17:00 hrs Arrival at Nairobi, Sarova Panafric Hotel
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0088..0000--0088..3300 hhrrss SSTTOOPP 11:: TTHHEE GGRREEAATT RRIIFFTT VVAALLLLEEYY VVIIEEWW PPOOIINNTT
View the Great Rift Valley, Mt. Longonot, Mt. Suswa and Mt. Margaret
LLOONNGGOONNOOTT
Longonot volcano consist of a cone which rises 1000 m above the rift floor and has a gentle slope to the
south. Arcuate ridges extend around the western and the southern side of the cone and are topographic
expression of a caldera rim. The main events of the
volcanological history of Longonot volcano are
outlined below:
Building of a shield.
Caldera formation. Building of pyroclastic and lava cones. Formation of the summit crater.
Flank and crater flooreruptions.
The age of the last eruptions at the northern flank and
the caldera floor is about 200 years BP. Surface
studies were carried out in Longonot in 1998 and
from the Geoscientific studies the prospect has a
potential of 650 MWe.
Plate 1: Longonot crater
SSUUSSWWAA
Plate 2: Aerial view of Suswa caldera
Figure 1: Geological map of Longonotprospect.
Suswa is the southernmost of a series of
Quaternary caldera volcanoes in the Kenya rift.
The volcano has two nested calderas: outer andinner with diameters of 10 and 4 km,
respectively (see picture). Volcanism at Suswa
that comprised trachytes and phonolites started
about late Pleistocene and continued to less than
1,000 years ago (Omenda, 1997).
Results from detailed surface studies suggest
reservoir temperatures of 250oC based on gas
geothermometry. Seismic and gravity studies
show that the heat source under the caldera is at
about 6-8 km deep with a NE-SW bias. The
estimated potential of the prospect is >600MWe.
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Figure 2: The excursion route around the Greater Olkaria geothermal field
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GGeeoollooggyyThe Olkaria geothermal area is located within the Greater Olkaria Volcanic Complex which consists of a
series of lava domes/flows and ashes; the youngest (Ololbutot) of which was dated at 180 50 yr BP
(Clarke et al., 1990). It is believed that the intrusive portions of these magmas are responsible for the high
heatflow in the area. Rhyolitic volcanism, which is so prominent in the Olkaria area, commenced about
400,000 years ago. Olkaria Hill is the main landmark in the area and the fields are named according to
their position with respect to the Hill.
Figure 3: Geological map of Olkaria Geother-mal Area.
Plate 3: View of Olkaria Hill from the East.Explosion craters and rhyolite dome are visiblein the photo.
GGeeootthheerrmmaall PPootteennttiiaallTo date, over 120 geothermal wells have been
drilled in Olkaria. The current installed power
potential at Olkaria stands at 174 MWe.
However, it is estimated that the geothermalpotential of the entire area could exceed 800
MWe. Olkaria geothermal area has been divided
into seven development sectors out of which
only three are committed to development. The
sectors (fields) are Olkaria East, Olkaria North
East, Olkaria South West, Olkaria Central,
Olkaria North West, Olkaria South East and
Olkaria Domes. The fields are named in respect
to the Olkaria Hill.
GGRREEAATTEERR OOLLKKAARRIIAA EXCURSION PROGRAMME
1100::0000--1100::3300 hhrrss SSTTOOPP 22:: OOLLKKAARRIIAA IIII PPOOWWEERR PPLLAANNTT
10:30-11:30 Tour of Olkaria II Power plant
Thirty three wells were drilled in Olkaria North East field and twenty-two wells are connected to Olkaria
II power station. Most of the wells produce from the Olkaria fault that runs ENE-WSW. All the discharge
brine is being re-injected hot at the borders of the field. The power plant was commissioned in 2003. An
additional 35 MWe unit is being constructed and will be commissioned in 2010.
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Plate 4: Photo showing Olkaria II power plant
1111::0000--1122::0000 hhrrss SSTTOOPP 33:: OOSSEERRIIAANN GGRREEEENNHHOOUUSSEE PPRROOJJEECCTT
11:10-12:00 Guided tour of Oserian Greenhouse Project
Plate 5: Oserians greenhouse heating usinggeothermal steam
The primary aim of Oserians greenhouseheating is to control night-time (and wet season)
humidity levels in the greenhouses, thereby
alleviating fungal disease. The project utilizes
steam from well OW-101, which is one of the
early exploration wells in that sector of the field.
Tests have shown the well to have a typical
average output of about 8 or 9 MWth. CO2
within the greenhouses is used to provide
enriched levels of CO2 in air, which result in
improved plant growth as well as a reduction in
disease due to traces of H2S. The heating system
uses plate heat exchangers (PHEs) fortransferring the geothermal heat into the
secondary fresh water loop.
12:00-13:00 STOP 4: TOUR OF OLKARIA DOMES FIELD
12:00-13:00 Tour of Olkaria Domes, drilling rigs and discharging well
Surface exploration in Olkaria Domes field was completed in 1993 and drilling of the three exploration
wells were carried out in 1998-1999. Drilling of 6 appraisal wells started in 2007 and the results from thedrilled wells updated the conceptual model which led to the siting and drilling of the production wells.
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GDC is currently drilling more production wells using hired Chinese Contractor. The field is earmarked
to be developed as Olkaria IV.
Plate 6: View of the Domes area from the north.
Plate 7: Drilling well OW-903B at Olkaria Domes. Plate 8: A well discharging at Olkaria Domes
14:30-15:00 STOP 5: MAASAI CULTURAL CENTRE
Visit the Maasai cultural Centre Drive through Hells Gate Park
The Maasai is one of the acknowledged
indigenous communities living adjacent to
the power plant. In the Maasai village,
there is a Cultural Centre, which is a
major attraction for visitors interested in
learning more about the Maasai culture.
They also demonstrate to the visitors how
they construct their traditional huts. The
Morans wear their traditional regalia and
display dance shows.
Plate 9: Maasai dancers performing at the Maasai Cultural Centre
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15:00 Drive through Hells Gate Park
Most area of the park lies within the Ol Njorowa Gorge. The gorge developed from about 9,000 yearsago due to erosion caused by southward outflow during the high stands of the old Lake Naivasha. The
erosion cut through ashes to depths of between a few metres to more than 200 m in the south leaving
volcanic necks/plugs that dot the landscape of the gorge.
Hells Gate National park was gazetted in 1984, two years after commissioning of first unit of Olkaria Ipower plant. The park derives its name from the northern end of the Gorge, which due to its nature was
dubbed as the gate to hell! The park has a variety of flora, fauna and avifauna. Among the animals
include giraffe, zebra, buffalo, antelope etc. Birds include ostrich, eagle etc. As a measure for sustainable
utilization of resources at Olkaria, KenGen signed a memorandum of understanding with Kenya Wildlife
Service which is the organization charged with the responsibility of managing the park.
Plate 10:View of Hells Gate Park from Elsa KWS Gate. In the centre is Fischers Tower, a volcanic plug, named
after a German explorer who visited the area early last century.
17:00 Arrival Sarova Panafric Hotel
END OF EXCURSION