8. Field Guide Olkaria Oserian Domes 150310

7/31/2019 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

8. Field Guide Olkaria Oserian Domes 150310

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