Topography Divisions Stratigraphy Geophysical Survey Previous work

1. Geological and Stratigraphic Modeling
Of Pasni West Block, Makran Pakistan
Muhammad Ahmad Raza
Department Of Earth And Environmental
Science

2. MY TOPIC IS
 Topography – figure
 Divisions ----- Dolati , Figures , description, why
divide,
 Stratigraphy --- Chart, seal , R , Cap, porosity, per,
 Geophysical Survey --- Marine survey,
 Previous work ---- seismic lines

3. INTRODUCTION TO THE STUDY AREA
 The Pasni West Block covering an area of 2293 sq
km is located in Gwadar district of Balochistan
Province.
(DGPC, 2011)

4. (DGPC, 2011)

5. TOPOGRAPHY
 Pasni town, like the rest of Makran Coast, is affected by a seismic
fault line (Makran Accretionary Front) caused by the northward
movement (40–50 mm/year) of the Arabian Plate against the
Eurasian Plate.
 Tectonic activity emanating from this subduction zone.

7. STRATIGRAPHIC SEQUENCE
 Stratigraphy of the makran fold belt ranges in
age from cretaceous to pleistocene. Oligocene to
pliocene sediments are exposed in southern
makran foldbelt.
 The sedimentary pile in the area is around
7000m thick in the coastal makran area.

8. STRATIGRAPHIC CHART
OF STUDY AREA:
The Hoshab formation ranging
in age from Late Oligocene to
Early Miocene is the oldest dated
series in the Makran prism.
The Panjgur formation, Middle
Miocene in age, it has a wide
distribution in the coastal area
and in the central prism.
The Parkini formation, has a
wide distribution along the
coastal range, well exposed
along the road from Pasni to
Turbat.
The Pliocene Hinglaj formation
is composed of light-grey
mudstones and fine-grained
sandstones.
The Chatti formation from
Lower Pleistocene is exposed
along the coastal road in the East
of Makran.

9. TECTONOSTRATIGRAPHIC CHART ALONG
THE FRONTAL PART OF THE MAKRAN
ACCRETIONARY PRISM

10. SOURCE ROCK
 Geochemical studies of surface samples from Makran indicate slope
to basinal facies of the Miocene Parkini formation to be potential
source rock.
 TOC occasionally exceeds 1% but is compensated by large volume
of mud rock.
 Geothermal gradient is low, about 2° C./100 m

11. RESERVOIR
 Mid to Upper Miocene turbidites (Panjgur and Parkini formations)
deposited in stacked sequences ponded above thrusts on the lower part
of the accretionary prism.
 Lithologically these turbidites are fine to coarse grained sandstones with
shales.
 Laboratory analysis of Panjgur samples show that the sandstone
horizons have porosities in the range of 2.36 % to 18.07%.
 These sandstones offer good target as reservoir in the block area.

12. SEAL
 Shale horizons of abyssal sediments in Middle to Upper
Miocene (Panjgur and Parkini formations) are
characterisly fine grained and well cemented which
might provide an adequate seals.

13. GEOLOGICAL FRAMEWORK
 Tectonically the block lies in Southern Makran Fold Belt
(Coastal). The Makran Coast is 800 km stretch of coastline
which extends east from the vicinity of Karachi, west into Iran.
 This coastal area is geologically recognised as an
accretionary complex where the Arabian Ocean Plate is
moving northward and subducting beneath continental crust of
the Eurasian Plate.
 The accretionary complex consists of a low-taper wedge of
deformed Late Eocene to Pliocene clastic sediments.

14. (DGPC, 2011)

15. DIVISION OF MAKRAN
 Makran is divide on the basis of changes in litho-
stratigraphic content and structural pattern by major
thrust faults.
 The units will become
 Norther makran
 The inner makran
 The outer makran and
 The coastal makran (dolati, 2010; burg et al., 2012).

16. FOUR TECTONIC-STRATIGRAPHIC UNITS OF
MAKRAN

17. NORTH MAKRAN
 North Makran is dominated by mafic to intermediate igneous rocks of
Cretaceous age in general.
 linked with deep marine sediments.
 This area mainly consists of Cretaceous formations and some small
outcrops of Paleocene and Eocene rocks.
 tectonic mélanges in which igneous rocks and deep-water sediments
are involved.
Dolati et al.

18. THE INNER MAKRAN
 Inner makran shows mainly upper eocene to lower miocene
turbidities.
 All present folds are close to tight.
 Commonly inter-linked with axial-plane cleavage.
 In this area, sedimentary deformation is testified by growth
structures
Dolati et al.

19. THE OUTER MAKRAN
 The Outer Makran, between the Ghasr Ghand and the Chah Khan
Thrusts.
 mainly consists of Lower Miocene to Middle Miocene formations.
 Outer Makran generally consists of Lower to Middle Miocene
Siltstones and Marls with calcareous sandstones.
Dolati et al.

20. THE COASTAL MAKRAN
 This province includes Late Miocene to Pleistocene
formations. It extends from the Chah Khan Thrust,
in the north, to the coastal line of Makran, to the
south.

21. GEOPHYSICAL SURVEY
 Geophysical survey methods are becoming increasingly accepted
and implemented in the field of mineral exploration. These surveys
provide a reasonably reliable idea of the types of minerals and
hydrocarbons present below the ground without any actual digging
or tunnelling.
 There are several different methods available to geophysical survey
companies that offer differing levels of detail along with different
costs of implementation.

22. A VARIETY OF METHODS
 Seismic Tomography – uses resistance to ground vibration
waves to gain a three dimensional map of an area.
 Ground Penetrating Radar – uses radar pulses to get an
image of the Earth's crust.
 Magnetometers –instruments used to calculate the strength
and direction of a magnetic field.
 Gravity – measures changes in gravitational acceleration on
the Earth's surface.
 Radiometrics – measuring the amount of potassium, thorium
and Uranium radiation on the Earth's surface.

23. SEIMIC SURVEYS
 Oil and gas explorers use seismic surveys to
produce detailed images of the various rock types
and their location beneath the Earth's surface and
they use this information to determine the location
and size of oil and gas reservoirs.

24. THE SEISMIC METHOD
Listening Devices 0 s

An Explosion! 0 s
Energy
Source .1 s.2 s.3 s
Some Energy is Reflected
Most Energy is Transmitted
.4 s.4 s .5 s
Some Energy is Reflected
Most Energy is Transmitted
.6 s.7 s.8 s.8 s

25. SEISMIC ACQUISITION
• A 3D survey is designed based on:
– Imaging Objectives: image area, target depth, dips, velocity,
size/thickness of bodies to be imaged, etc.
– Survey Parameters: survey area, fold, offsets, sampling, shooting
direction, etc.
Land Operations
Vibrators Generate a Disturbance
Geophones Detect Motion
Marine Operations
Air Guns Generate a Disturbance
Hydrophones Detect Pressure

26. MARINE SURVEY
 Tows an array of sensors (hydrophone streamer cables)
through the water at an average speed of 4-5 knots and fires A
seismic source array (airguns) every 6-13 seconds to map the
geophysical attributes of the subsurface.
 Acoustic energy created from the discharge of compressed
air into the water travels to the ocean floor and begins A series
of refractions and reflections off multiple subsurface layers.In
deepwater marine seismic.

27. MARINE SEISMIC OPERATION
Instruments are required
 Seismic sensors
• geophones
• Hydrophones
• accelerometers
 Sources
• Explosives or air gun
Acquisition Parameters
• Time Sample Rate
• Offset Range
• Listen Time
• Sample Rate and Temporal
Aliasing
• Geophone Spacing and
Spatial Aliasing
• Shooting geometry
• inline
• cross-line

28. MARINE SEISMIC METHOD
 The mechanism of imparting energy into the substrate is
quite complex in the marine, as opposed to land surveys,
due to a highly-conductive water column and the
separation of the source and the sea floor.

29. LAYOUT

30. SEISMIC SURVEY VESSEL

31. RAW DATA - MARINE

32. SEISMIC PROCESSING
Field Record
(marine)
Data Processing
Stream
Subsurface ‘Image’