COMPARISON BETWEEN KENYA TERTIARY RIFT AND LIAODONG BAY DEPRESSION

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NOT AN OFFICIAL UNCTAD RECORD
COMPARISON BETWEEN KENYA TERTIARY RIFT AND
LIAODONG BAY DEPRESSION
11th Africa Oil Gas, Trade Finance Conference
Exhibition Kenya 2007 23th-25th May 2007
Nairobi, Kenya
Wu Keqiang Senior Geologist Research
CNOOC Beijing China Tel [phone] Email
Wukq_at_cnooc.com.cn
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ACKNOWLEDGEMENTS

• Colleagues at CNOOC
• CNOOC International Limited
• Science and Technology Development Department,
  CNOOC
• Research CNOOC
• 11th Africa Oil Gas, Trade Finance Conference
  Exhibition

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OUTLINE

• Introduction of Kenya Tertiary Rift and Liaodong
  Bay Depression
• Petroleum Geological Comparison of Kenya
  Tertiary Rift and Liaodong Bay Depression
• Advice and Conclusion

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OUTLINE

• Introduction of Kenya Tertiary Rift and Liaodong
  Bay Depression
• - Location and Exploration
• - Why Liaodong Bay Depression
• Petroleum Geological Comparison of Kenya
  Tertiary Rift and Liaodong Bay Depression
• Advice and Conclusion

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The Location of Kenya Tertiary Rift
Kenya Tertiary Rift locates in the western part
of Kenya, develops in the eastern branch of the
East African Rift System.
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The Exploration Statue of Kenya Tertiary Rift
FRONTIER AREA Aera 38,904
km2 Wells 2 Seismic 2-D
7,652 km
Eliye Springs 1
Loperot 1

• Loperot 1 located in the southern part of the
  Lokichar Trough.
• Encountered two lacustrine shale intervals with
  very good source rock potential.
• Recovered some 9 liters of 29 API crude during a
  DST.
• Eliye Springs 1 was drilled in the southwestern
  part of the Turkana Graben. The well was
  abandoned as dry.

From nation oil corporation of Kenya
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The Loacation of Liaodong Bay Depression
LIAODONG BAY DEPRESSION
Liaodong Bay Depression (LBD) locates on the
northern part of Bohai bay basin, China, covers
an area about 15,300 square kilometers.
BOHAI BAY BASIN
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The Exploration Statue of Liaodong Bay Depression
Aera 15300 km2 Wells
120 Seismic 2-D 18,000km
120 exploratory and delineation wells were
drilled, 79 wells got oil flow, 9 oil gas
fields and 19 oil beared structures have been
discovered. The geological success rate is 66.
JZ31-6
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Analog, why LBD?

• Comparative analysis is the most popular way at
  the beginning of studying a frontier area. 3
  reasons exit, why Choosing the Liaodong Bay
  Depression (LBD) as the analog to compare with
  KTR.
• Basin type is similar-rift
• Shape is similar-stripe
• Framework of basin is similar-half grabens
• Comparing the basin origin, the petroleum geology
  and accumulation process of KTR with LBD, may
  obtain several good advices and ideas for
  exploration in KTR.

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The Basins Type
Liaodong Bay Depression
Tan-Lu fault system
From nation oil corporation of Kenya
Xu Shouyu,2005
Kenya tertiary rift, is a new episode succeeded
the Cretaceous-Paleogene one. This mainly N-S
trending rifting phase has active since the
Eocene and is responsible for the creation of a
string of half graben sub-basins. Liaodong Bay
Depression sits astride the Tan-Lu fault system
of eastern China, one of the world's largest
strike-slip fault systems.
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The Basin Shape
The structure framework of Liaodong Bay
Depression
?
?
A
?
B
?
?
Basin Boundary
Tan-lu fault
Shore line
B
section
rise
sag
A
? Liaoxi sag ? Liaoxi rise
? Liaozdong sag ? Liaodong rise ?
Liaozhong sag
Both of KTR and LBD are all narrow, elongated
system of normal faults.
From nation oil corporation of Kenya
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The structural framework
Liaoxi Uplift
Liaodong Uplift
Liaozhong sag
Liaodong sag
Liaoxi sag
Zhang Gongcheng
E-E.N1
Precanbrian basement
From nation oil corporation of Kenya
Major extensional faults in the KTR define
separate Basins with distinctive structural and
geological setting. Five basins are included in
KTR, Turkana onshore, Kerio, North Lokichar,
Lokichar, South Kerio Trough. LBD consists of 3
sub-basins(sags) and 2 rises, Liaoxi
sag,liaozhong sag,liaodong sag, liaoxi rise,
liaodong rise.
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OUTLINE

• Introduction to Kenya Tertiary Rift and Liaodong
  Bay Depression
• Petroleum Geological Comparison of Kenya
  Tertiary Rift and Liaodong Bay Depression
• - Structure Evolution
• - source rock
• - Reservoir and Cap
• - Habitat of LBD
• - Geological risks of KTR
• Advice and Conclusion

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Structural Evolution
From nation oil corporation of Kenya
During the tectonic evolution, KTR underwent the
rifting stage Only, which may initiated from
Eocene, at the end of Neogene, regional uplifting
occurred. LBD began its evolution in Paleocene,
ungerwent 3 stage such as, rifting stage, failed
rift stage and reactive stage.
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The petroleum geology- source rock
Lokhone shale
Lopreot shale
From nation oil corporation of Kenya
Two major lacustrine shale source rock intervals,
which were penetrated by Loperot-1, in KTR, aged
Miocene and Oligocene respectively, are low to
high mature. The major source rock in LBD, is
Shahejie Formation, lacustrine shale, which was
aged Eocene.
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The petroleum geology- source rock
ITEMS KENYA TERTIARY RIFT LIAODONG BAY DEPRESSION
Age Miocene, Oligocene Eocene
Thickness(m) About 200 About 400-1200
TOC() 2.86(Ave.) 1.02-7.69 1.02-2.32
Type of Kerogen II II
HI 508(Ave.) 186-748 290-454
Lithofacies Lacustrine shale Lacustrine shale
Degree of Maturity Lokhonelow-Mature LoperotMature to high mature Mature to high mature
Data Daniel M. Jarvie, 2005 CNOOC
Besides the thickness penetrated by wells,
several characters of source rock in KTR are
similar with LBDs. Some items of KTR are better
than LBDs.
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The petroleum geology- source rock
From the classification and potential assessment
diagram of organic matter, both of organic
matters in KTR and LBD, belong to type II, and
lot of samples distribute in good to excellent
area.
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Source rock in Lokichar basin
Loperot Shale Member, which is mature to
high-mature.
Lokhone Shale Member, which is low-mature to
mature.
Potential generating capacity of Lokhone Shale
Member is estimated at 10.5 billion barrels.
Given that about 40 of the shale volume is at
mid to post mature levels this suggests the
Lokhone Shale Member could have generated about 4
billion barrels of oil. After Marine and
Petroleum Geology 21 (2004) 6378
From nation oil corporation of Kenya
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The petroleum geology- reservoirs and seals
From nation oil corporation of Kenya
On the base of two shale segments, III reservoir
and cap assemblages were identified in KTR. 3
assemblages exit in LBD, E2d, E2-3s,
Pre-T(carbonate and volcanic).
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The oil quality

• KTRTested oil 29o API (0.883)
• LBDheavy oil
• API 17.4o (Ave.)
• APIlt22.3(0.92) 86
• The oil quality of KTB is better than LBD.

From nation oil corporation of Kenya
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The oil habitat of LBD-source, play
Zhang Gongcheng
Liaozhong sag
Liaodong sag
Liaoxi sag

1. The favorable sag controls the fields
   distribution. About 80 reserves distribute
   around Liaozhong sag.
2. The favorable assemblage controls the most
   favorable play. Ed, the major play in LBD,
   deposited almost 90 reserves.

Liaozhong sag
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The oil habitat of LBD-zone, pool
Inner sag
Gentle slope
Steep slope
rise
Fault block
Anticline pool
Lithologic pinchout
structural-stratigraphic
buried hill pool
Turbidite pool

• 4 types of oil accumulation zonesRise, Steep
  slope zone, gentle slope zone, Inner graben.
  Almost 90 reserves deposit in gentle zones and
  rises.
• Sand body and fault made up of the major
  transport system by which oil and gas charged
  into the pools. Multiple types of oil pools are
  found in LBD.

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perspective gas layer
Proved gas layer
Absorption analysis profile Liu Zhibin,2006
root mean square(RMS) amplitude of on-horizon
slice Zhao Rumin,2005
Produced 11.7 mmcf/day in DST, (choke 11.91mm)
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The geological risks of KTR- source rock
The distribution of two layers source rock is
limited.
From nation oil corporation of Kenya
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Heat Flow Distribution in Kenya
Anza basin
The maturity of source rock influenced by local
heat flow, such as lava, obviously, it is
difficult to identify the range of active pods.
Lokichar basin
From nation oil corporation of Kenya
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The geological risks of Kenya Tertiary Rift
From nation oil corporation of Kenya
During late Neogene to present, after oil
accumulated, regional uplifting and erosion
occurred, so another risk is preservation
condition.
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OUTLINE

• Introduction to Kenya Tertiary Rift and Liaodong
  Bay Depression
• Petroleum Geological Comparison of Kenya
  Tertiary Rift and Liaodong Bay Depression
• Advice and Conclusion
• - Three step source-transport-play
• - The critical technology seismic

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• In LBD,
• the favorable oil generating sag (Liaozhong sag)
  control the oil field distribution.
• the favourable reservoir rock and cap rock
  assemblage (Ed) controls the rich-play.
• The gentle zones and rises controls almost 90
  reserves.
• Multiple oil pools are found in LBD
• In the frontier area, such as KTR, according to
  the exploration program and the primary factor
  controlling the oil distribution of LBD, 3 points
  should be noticed during exploration activity.
• looking for the favorable basins and grabens
• looking for the favorable reservoir and cap
  assemblage
• looking for the favorable oil accumulating zones.

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The distribution of basins in KTR

• 5 basins
• Lokichar basin is the best one.
• area
• thickness
• Source rock layer
• Oil seep or show

From nation oil corporation of Kenya
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From nation oil corporation of Kenya
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EROSION Among the three reservoir and cap
assemblages, the lower assemblages may be the
best one.
From nation oil corporation of Kenya
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Lava and Seismic technology
From nation oil corporation of Kenya
At least two periods volcanics exist in KTR. They
covered the deposits below them, brought the
shielding effect on seismic profiles. In KTR, the
structural framework cannot be divided clearly,
the lithofacies cannot be identified reliably,
because of the shielding effect.
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• Eliminating the shielding effect of lava, can
  obtain better seismic image. Thus the uncertainty
  and risk during exploration process can be
  decreased. So advanced seismic acquisition and
  processing technology is necessary.
• Improve the reliability of sediment facies.
• Study the framework of basin.
• Improve the reliability of trap interpreted from
  seismic datas.

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CONCLUSION

• Kenya tertiary rift is similar with Liaodong bay
  depression in basin type, shape and framework.
• They are differences in structure evolution and
  some factors of petroleum geology.
• Kenya tertiary rift have good source rocks.
• The area of active source rocks and the
  preservation post oil charging are geological
  risks for exploration. The latter is the worst
  one.
• The oil habitat of Liaodong bay depression is
  useful for Kenya tertiary rift during exploration
  activity. The first step is to identify the
  favorable generating grabens, then to find the
  favorable area having good preservation
  condition.
• Improve the seismic quality can decrease the
  geological risks and costs.

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