Exploration Significance of Unconformity Structures on Subtle Pools Kongyou Wu, Ph. D Associate...
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Transcript of Exploration Significance of Unconformity Structures on Subtle Pools Kongyou Wu, Ph. D Associate...
Exploration Significance of Unconformity Structures on Subtle Pools
Kongyou Wu, Ph. D
Associate Professor
China University of Petroleum (Huadong)College of Geo-Resources and Information
Add:66 Changjiangxi Rd., Economic & Tech. Development District, Qingdao, Shandong Province, 266555, P. R. China
Exploration Significance of Unconformity Structures on Subtle Pools
1 Vertical structural characteristics of unconformity
2 Lithologic configuration of unconformity
3 Significance of vertical structures of unconformity to hydrocarbon accumulation
4 Physical simulations of oil migration and accumulation in unconformity
Outline
Exploration Significance of Unconformity Structures on Subtle Pools
1 Vertical structural characteristics of unconformity
Using the interpreting results of seismic and logging data, b
ased on the core and outcrop observation, the structures of
unconformity can be divided into three layers vertically:
①rock above the unconformity surface
( including transgressive sandstones and basal conglomerate )
②weathered clay
③leached rock
First
Exploration Significance of Unconformity Structures on Subtle Pools
Outcrop
a-leached rock ;b-weathered clay ;c-transgressive sand
stones ;d-basal conglomerat
e a
b
d
c
b
a
a
First
(1)
(2)
(3)
(4)
Exploration Significance of Unconformity Structures on Subtle Pools
First
Core Z18 Z28
dc
b b
a a
b
a
d QG3
a-leached rock ; b-weathered clay ;c-transgressive sandstones ; d-basal conglomerate
Exploration Significance of Unconformity Structures on Subtle Pools
First
Logging response
Every layer has the different logging response
Structures
Rock above
the uncon-formity surface
Weathered clay
Leached rock
Litho-logy
Logging response Logging response Logging response Logging responseLitho-logy
Litho-logy
Litho-logy
Conglo-merate Sand Mud Coal
Clay
Conglo-merate Sand Mud Lime-
stone
Dolomite Granite Metamorfic
rock
Lack
Exploration Significance of Unconformity Structures on Subtle Pools
First
Tectonic movement, ancient landform, arid climate and
exposed period were the key factors to control the types of
rock above the unconformity surface.
Exploration Significance of Unconformity Structures on Subtle Pools
First
Rock is subjected to weathering and leaching ,when it exposes the
earth's surface, resulting in secondary pores, holes and joints.
Therefore, the leached rock contains amount of secondary
porosity .
Scanner
Outcrop
Feldspar
Limestone
Exploration Significance of Unconformity Structures on Subtle Pools
1 Vertical structural characteristics of unconformity
2 Lithologic configuration of unconformity
3 Significance of vertical structures of unconformity to hydrocarbon accumulation
4 Physical simulations of oil migration and accumulation in unconformity
Outline
Exploration Significance of Unconformity Structures on Subtle Pools
Second
2 Lithologic configuration of unconformity
When the weathered clay has a little thickness or limited
distribution, the overlying and underlying strata will contact
directly, and the lithologic configuration is often different. T
his lithologic difference causes different fluid transporting ca
pacity. It also determines whether a trap can be formed or n
ot, and what kind of trap can be formed.
Unconformity develops three types of the lithologic configuration vertically:
basal conglomerate - weathered clay(or lack) – leached rock type ( ),Ⅰ
transgressive sandstone - weathered clay(or lack) – leached rock type ( ),Ⅱ
sandy mudstone – leached rock type ( ).Ⅲ
Exploration Significance of Unconformity Structures on Subtle Pools
Second
( )Ⅰ
( )Ⅱ ( )Ⅲ
Silty mudstone
Silty mudstone
mudstone
mudstone
Exploration Significance of Unconformity Structures on Subtle Pools
1 Vertical structural characteristics of unconformity
2 Lithologic configuration of unconformity
3 Significance of vertical structures of unconformity to hydrocarbon accumulation
4 Physical simulations of oil migration and accumulation in unconformity
Outline
Exploration Significance of Unconformity Structures on Subtle Pools
Third
3 Significance of vertical structures of unconformity to hydrocarbon accumulation
3.1 Sealing capability of vertical structures of unconformity
Weathered clay contains the fine particles residual material formed by
weathering, and would become very strong by the compaction of overlyi
ng sediments. Thus, it is a strata with good sealing capability 。
y = 0. 8007e0. 0016x
0
5
10
15
20
25
30
0 500 1000 1500 2000 2500深度(m)
突破
压力
(MP
a)
Depth
Bre
akth
rou
gh
Pre
ssu
re
Horizontal axis
Ver
tica
l ax
is
Exploration Significance of Unconformity Structures on Subtle Pools
Third
3.2 Conduction of vertical structures of unconformity
When the unconformity surface was gentle, the d
eposited transgressive sands or basal conglomerates w
ould connect with each other, thus a migration channel
would be formed.
Exploration Significance of Unconformity Structures on Subtle Pools
Third
3.3 Trap of vertical structure of unconformity
When the unconformity surface was in a slope-break zone d
uring the early transgression, the deposited sands would be c
overed by the lateral mudstones, thus a trap of the stratigra
phic overlap or a lithologic pinch would be formed.
Exploration Significance of Unconformity Structures on Subtle Pools
1 Vertical structural characteristics of unconformity
2 Lithologic configuration of unconformity
3 Significance of vertical structures of unconformity to hydrocarbon accumulation
4 Physical simulations of oil migration and accumulation in unconformity
Outline
Exploration Significance of Unconformity Structures on Subtle Pools
Fourth
4 Physical simulations of oil migration and accumulation in unconformity
Simulation experiments showed that the oil migration along the unconformity
was controlled by the petrophysical parameters and the angles of slope. The t
raps above the unconformity surfaces were more favorable than the traps bel
ow the unconformity surfaces to entrap oil and gas.
Acknowledgements
National Natural Science Foundation of China
(No.40772081) , and
Provincial Natural Science Foundation of
Shandong (No.Y2008E16) provided financial
support for this study.
We especially thank Xinjiang Oil Field
Company of Petro-China for the permission to
use their geological and geophysical data.
THANK YOUTHANK YOU !!