many Fields in the Upper Indus Basin are producing a reasonable amount of oil and gas. There are many prospects as well need to work upon them.

1. DEPARTMENT OF EARTH SCIENCES
SUBJECT: Petroleum Geology
PROGRAM: BS GEOLOGY
TOPIC: Five Petroleum Fields and their petroleum
system From Upper Indus Basin
BY: Salahudin
Khursheed
system From Upper Indus Basin

2. History of petroleum exploration in
Pakistan
• In 1866, the first oil well on the western Indian
subcontinent was drilled at Kundal (fi g. 13). The
first commercial oil discovery occurred in 1914
when the Attock Oil Company completed a 214-ft
well on a thrust-faulted anticline near the town ofwell on a thrust-faulted anticline near the town of
Khaur (Khan and others, 1986)
• Since the discovery, there have been more than 340
wells drilled in the field. Production at Khaur is from
Sakesar and Murree Formation reservoirs.
2

3. • Drilling from 1920 to 1935 resulted in success at
Dhulian, a structural dome 17 km southeast of
Khaur. Other discoveries followed with Joya Mair in
1944, Balkassar in 1946, Karsal in 1956, and Tut in
1967.
• The first commercial gas field—Adhi—was found in
1979. The Adhi gas field produced from rocks1979. The Adhi gas field produced from rocks
ranging in age from Cambrian to Eocene (Petro
consultants, 1996).
• Eighteen oil and three gasfields were discovered in
the Kohat-Potwar geologic province between 1915
and 1996
3

4. • The largest oil and gas field found to date is the
Dhurnal field with areal closure of 13.5 km2 and
vertical closure of 500 m. The initial in-place oil
estimate for Dhurnal was 102 MMBO (million
barrels of oil) (Jaswal and others, 1997.
• In a more mature area, the number of wildcat
wells required to find the same volume of oil
would be expected to increase and the curves onwould be expected to increase and the curves on
the plots to flatten.
• The largest field may have already been found,
but potential for additional oil and gas
discoveries in complex structural traps remains
good.
4

5. Basinal Division Of Pakistan
The Basins of Pakistan can be classified into
two main basins;
• Indus Basin.
• Baluchistan Basin.• Baluchistan Basin.
These basins evolved through different
geological episodes after which they were
welded together during Cretaceous/Paleocene
age along Chaman strike slip faults.
5

6. 6

7. Indus Basin
The geological history of the Indus Basin predates
to Precambrian age.
 Classification Of Indus basin:
• Upper Indus Basin• Upper Indus Basin
1.Kohat sub-basin
2.Potwar sub-basin
• Lower Indus Basin
1.Central Indus basin
2.Southern Indus basin
7

8. Upper Indus Basin
• Production History:
• First commercial well was drilled by Attock Oil
Company at Khaur Village upto depth of 214 ft at a
thrusted anticline.
• Production at Khaur is from Sakesar and Murree
Formation reservoirs.Formation reservoirs.
• Drilling from 1920-1935 resulted in discovery of
Dhulian, a structural dome 17 km southeast of
khaur.
• JoyaMair in 1944, Balkassar in 1946, Karsal in 1956,
and Tut in 1967.
The first commercial gas field—Adhi—was found in
1979. 8

9. Cont...............,
•The largest oil and gas field found to date is the
Dhurnal field with areal closure of 13.5 Square
km’s and vertical closure of 500 m. The initial in-
place oil estimate was 102 MMBO (million
barrels of oil).
9

10. Source Potential:
• Paleocene Patala Formation appears to be the
primary source of hydrocarbons.
Other Source Rocks include:
•Late Proterozoic–Lower Cambrian Salt Range;
Permian Wargal, Sardhai, and Chhidru; PaleocenePermian Wargal, Sardhai, and Chhidru; Paleocene
Lockhart and Eocene Patala Formations (OGDC,
1996; and Qadri, 1996).
•Chichali and Lumshiwal Formations—may be the
youngest mature rocks with source potential
throughout most of the Kohat Plateau.
10

11. Thermal Maturation:
•Thermal maturities for Kohat-Potwar rocks
range, from Ro 0.3 to more than 1.6 %.
•vitrinite reflectance of Tertiary rocks is 0.62 to
1.0 %
•0.6 to 1.1 % for Cretaceous, 0.5 to 0.9 % for•0.6 to 1.1 % for Cretaceous, 0.5 to 0.9 % for
Jurassic, and 0.65 to 0.95% for Permian rocks
(Tobin and Claxton, 2000).
11

12. Reservoir Rocks
•Cambrian: Kherwa, Kussak, and Jutana;
•Permian: Tobra, Amb, and Wargal
•Jurassic: Datta;
•Cretaceous: Lumshiwal;•Cretaceous: Lumshiwal;
•Paleocene: Khairabad, Lockhart, Patala, and
Nammal;
•Eocene: Bhadrar, Chorgali, and Margala Hill
Limestone; and
•Miocene: Murree. 12

13. Generation And Migration:
•Generation of hydrocarbons most likely began in
Late Cretaceous time for Cambrian through Lower
Cretaceous source rocks and again from Pliocene
time to the present for younger source rocks
(OGDC, 1996).
•Two distinct over pressuring regimes were•Two distinct over pressuring regimes were
reported by Law and others (1998).
•A Neogene overpressuring regime was attributed
to tectonic compression and under compaction,
and a pre-Neogene overpressuring
13

14. Cont..........,
• …….regime is attributed to combined
hydrocarbon generation and tectonic
compression.
• In many oil and gas fields, there are stacked
source and reservoir rocks possibly resulting in
mixing of oils. Migration is primarily overmixing of oils. Migration is primarily over
short distances updip and vertically into
adjacent reservoirs and through faults and
fractures associated with plate collision and
thrusting.
14

15. Traps and Seals
•Thick shales and clays of the Miocene and Pliocene
Siwalik Group Most of the fields discovered in the
Kohat-Potwar geologic province to date are either
overturned faulted anticlines, popup structures, or
fault-block traps. In this area, anticlinal features strike
generally east-northeast to west-southwest and are
approximately parallel to the plate-collision zone. Many
of these folded structures are amplified, or they are
approximately parallel to the plate-collision zone. Many
of these folded structures are amplified, or they are
only present above a detachment zone in Eocambrian
salts. The latest trap-forming thrust events began at
approximately 5 and 2 Ma (Jaswal and others, 1997).
Seals include fault truncations and interbedded shales
and the thick shales and clays of the Miocene and
Pliocene Siwalik Group .
15

16. Petroleum Fields
• Definition: Oilfield is an area of land from
where crude oil and natural gas is produced. It
can extend to multiple miles as hydrocarbon
reservoirs generally spread over a large areareservoirs generally spread over a large area
below the earth's surface. Multiple oil or gas
wells can be drilled in a single Oilfield.
Succinctly an Oilfield can be defined as a
surface area which is on top of the subsurface
accumulated hydrocarbon.
16

17. Five Oil Fields Of Upper Indus Basin
1- Joyamir Field
2- Meyal Field
3-Khaur Field
4-Adhi Field4-Adhi Field
5-Balkassar Field
17

18. 1-Joyamir Field
Introduction:
• The JoyaMair Oilfield lies in the south-southeast of
the Salt Range-Potwar foreland basin (SRPFB).
• The JoyaMair Oilfield is characterized as structural• The JoyaMair Oilfield is characterized as structural
trap in SRPFB (Salt Range-Potwar foreland basin).
• Reserve estimation based on different techniques
show recoverable reserves of 23-25 MMBO,
however, only 8 MMBO reserves are recovered so
far.
18

19. Hydrocarbon Potential:
•SRPFB has several features suitable for hydrocarbon
accumulation i-e continental margin, thick marine
sedimentary sequence, potential source, reservoir
and cap rocks.
•The thick overburden of 3047 m of molasse provides•The thick overburden of 3047 m of molasse provides
burial depth and optimum geothermal gradient for
oil formation.
•The SRPFB with an average geothermal gradient of
2°C/100 m is producing oil from the depth of 2750-
5200m.
19

20. Reservior
•The Cambrian, Permian, Jurassic, Paleocene and
Eocene reservoirs are producing oil in SRPFB.
•The fractured carbonates of the Sakesar and
Chorgali Formations are the major producing
reservoirs in JoyaMair area.reservoirs in JoyaMair area.
•The intergranular, intraskeletal, dissolution and
moldic porosity is common in the upper part of
Sakesar limestone.
•Interskeletal and intraskeletal porosity is mainly
common in Chorgali and Sakesarlimestones.
20

21. Source Rock
•The gray shales of the Mianwali, Datta and Patala
Formations are potential source rocks in SRPFB.
•The oil shales of the Eocambrian Salt Range
Formation include 27% to 36% TOC in isolated
pockets of shales, and are considered as the sourcepockets of shales, and are considered as the source
rock in SRPFB.
Cap Rock
•The Kuldana Formation acts as cap for the reservoirs
of Chorgali and Sakesarlimestones
•The clays and shales of the Murree Formation .
21

22. Oil Generation
•The JoyaMair area has Paleogene source rocks,
required depth and temperature for the
generation of oil
•The Paleogene source rocks achieved required
depth and 82°C temperature during thedepth and 82°C temperature during the
deposition of middle Chinji Formation.
•The area remained in oil window up to 1.8 Ma.
•Finally post 1.8 Ma uplift exhumed the Paleogene
source rocks from oil window leaving immature
oil in JoyaMair Oilfield.
22

23. Migration and Accumulation
•The Eocene carbonates of Sakesar and Chorgali
units show common intergranular,
intraskeletal, dissolution and moldic porosity.
•Primary porosity of lime stone is very low•Primary porosity of lime stone is very low
which average from 1-3%.
•The dominant secondary porosity in these
carbonates is the fracture porosity.
•These fractures are calcite filled, quartz filled
and open in nature.
23

24. Cont..............
•The most significant fractures are the open
fractures, which control the dominant
migration of oil in JoyaMair triangle zone.
•The oil migrated and accumulated in the
hanging wall anticlines of the southeasternhanging wall anticlines of the southeastern
and northwestern flanks of the triangle zone.
•The oil is trapped in the hanging wall anticlines
because the clays of Murree Formation lie in
the foot wall and above the Paleogene
reservoir.
24

25. 25

26. 2-Meyal Field
• Introduction:
Meyal Field is located in Attock district, near
PindiGheb, 110 kilometers southwest of Islamabad
in an active foreland and thrust belt in the Central
Potwar Plateau of the Upper Indus Basin .Meyal
Field is one of the major oil and gas producing fieldsField is one of the major oil and gas producing fields
in the Potwar Plateau. The field was discovered by
Pakistan Oilfields Limited in 1968. Discovery
resulted after 52 years of continuous exploration
efforts in the Meyal-Kharpa area. In 1916, soon
after the discovery of Khaur Field, the first well was
drilled which was terminated in the Molasse
sequence without reaching the Eocene. 26

27. • Exploration and Development History:
The Meyal-Kharpa surface feature had remained a
key target for petroleum geologists from the
onset. At Meyal, the first AOC well was drilled
during 1942-44 which was abandoned at 8490 feet
due to collapse of 8. 5/8 inches casing. AOC well-2
was drilled almost at the same site of well-11,was drilled almost at the same site of well-11,
Well-3 was drilled after re-mapping of the
structure on the anticlinal nose at the western end
of the structure. After drilling to a depth of 8,100
feet, the well had to be abandoned due to
mechanical reasons.
27

28. • Stratigraphy and Depositional History:
Rocks from Precambrian to Quaternary age are
present in the Potwar Plateau. These rocks, with
a total thickness of more than 26,000 feet, were
deposited in a variety of environments ranging
from marine to fluvial. Periods of uplift and
erosion were quite extensive, as indicated byerosion were quite extensive, as indicated by
several major unconformities The oldest rocks
penetrated in the Meyal Field are the Permian
clays, encountered at 14,360 feet in Meyal No.
13 well
28

29. Cont…..,The Permian and Triassic strata are
separated by an unconformity, reflecting a
regression of the sea and emergent conditions
persisted during Late Permian to Early Triassic,
followed by yet another marine transgression in
the Triassic. The rocks of Triassic, Jurassic and
Cretaceous age were deposited on a west-Cretaceous age were deposited on a west-
northwest facing passive margin after the breakup
of Gondwanaland with maximum development of
Mesozoic rocks in the western Potwar and Salt
Range, overlapped by Paleocene strata towards
the east (Yeats and Hussein, 1987;Hasany and
Khan, 1999). In the Meyal area 29

30. • Source Rock: detailed study had been carried out
by Sunmark Exploration Company under the title
of Geochemistry of Nine oils from the Potwar
Plateau region, Pakistan, during 1980. The report
suggests the possibility of the occurrence of two
source rocks in the Potwar Basin, Nammal shales
interpreted to be the major contributor of the oils
to the reservoirs of Dhulian (Chorgali-Sakesrar),to the reservoirs of Dhulian (Chorgali-Sakesrar),
JoyaMair(Sakesar), Khaur (Murree sandstone) and
Balkassar fields (Sakesar). Another potential
source rock considered actively participating
generation of oil is the Jurassic Variegated series.
This unit provided oil to the Meyal (Lockhart and
Jurassic and Sakesar) and Dhulian fields
(Variegated beds and Lockhart). 30

31. Cont………..,
• The chemistry of the oils found in the Meyal Field in
Sakesar, Jurassic and Paleocene reservoirs suggests
that the hiatus separating the Tertiary and the
Mesozoic is also the boundary between source
units that are in a state of moderate maturity
(Tertiary) and units that are in the advanced(Tertiary) and units that are in the advanced
maturity(Jurassic).
• However, the Eocene Chorgali-Sakesar carbonates
and shales of Paleocene Patala black marine shales
are also considered as the potential source rocks.
Derived data from nearby fields, where source rock
studies were carried out, support this view. 31

32. Seal Rocks
Nammal Formation:
The Nammal Formation is predominantly shale
with marl and soft argillaceous chalky
limestone. Shales of the Nammal are
developed all over the Meyal Field. A 45 to 108
feet thick unit provides a top seal to trap oil in
the Paleocene reservoirs.the Paleocene reservoirs.
Datta Formation:The top part of the Datta
Formation consists of varicolored shales,
siltstone, mudstone and claystone with thin
sands bed (Variegated Beds). considered to be
the top seal for the Jurassic reservoirs.
32

33. • Kuldana Formation:
The Kuldana Formation is mainly composed of
multi-colored shale (red, reddish brown and
purple), usually silty and brittle but occasionally
clayey and soft. The thickness of this formation is
120 to 192 feet in the Meyal Field. Due to its
impermeable and argillaceous character the
Kuldana Formation forms an effective seal overKuldana Formation forms an effective seal over
the Eocene reservoirs of the Meyal Field
• Reservoir Properties and Zonation: A detailed
reservoir zonation of the Eocene Chorgali-
Sakesar and their properties are described in
detail.
33

34. Cont......,
• This zone is the primary reservoir in the Meyal
Field where they can be divided into eight
different possible flow units. The top part of the
Chorgali Formation, which comprises of turquoise
marl and bluish green to gray shale with minor
light gray limestone, is excluded. The zonation is
based on the log response of Litho-density,based on the log response of Litho-density,
Neutron, Resistivity, SP, and Sonic logs.
• C1 – Topmost fractured limestone
• C2 – Shaly and marly interval, poor N/G C3 –
Dolomite
• C4 – Dolomitic limestone.
34

35. 35

36. 3- Khaur Oil Field
• Introduction:
The first commercial oil discovery occurred in
1914 when the Attock Oil Company completed a
214-ft well on a thrust-faulted anticline near the
town of Khaur (Khan and others, 1986). Since thetown of Khaur (Khan and others, 1986). Since the
discovery, there have been more than 340 wells
drilled in the field. Production at Khaur is from
Sakesar and Murree Formation reservoirs. Drilling
from 1920 to 1935 resulted in success at Dhulian,
a structural dome 17 km southeast of Khaur.
36

37. • Source Rock:
These include the Late Proterozoic–Lower
Cambrian Salt Range; Permian Wargal, Sardhai,
and Chhidru; Paleocene Lockhart; and Eocene
Patala Formations (OGDC, 1996; Quadri and
Quadri, 1996). Most of the available information
and analyses available was derived from samples
collected on the Potwar Plateau and easternmostcollected on the Potwar Plateau and easternmost
Kohat Plateau.
• Reservoir Rock: Reservoir rocks include Miocene
alluvial sandstones, Paleogene shelf carbonates,
Jurassic and Permian continental sandstones, and
Cambrian alluvial and shoreface sandstones
(Shah, 1977; Iqbal and Shah, 1980)
37

38. cont.......,
On the Potwar Plateau, oil or gas has been
produced from the following formations:
Cambrian Kherwa, Kussak, and Jutana; Permian
Tobra, Amb, and Wargal; Jurassic Datta;
Cretaceous Lumshiwal; Paleocene Khairabad,
Lockhart, Patala, and Nammal; Eocene Bhadrar,
Chorgali, and Margala Hill Limestone; andChorgali, and Margala Hill Limestone; and
Miocene Murree (Khan and others, 1986; Petro
consultants, 1996).
• Taps and Seals: Most of the fields discovered in
the Kohat-Potwar geologic province to date are
either overturned faulted anticlines, popup
structures, or fault-block traps.
38

39. • . In this area, anticlinal features strike generally
east-northeast to west- southwest and are
approximately parallel to the plate-collision
zone. Many of these folded structures are
amplified, or they are only present above a
detachment zone in Eocambrian salts. The latest
trap-forming thrust events began attrap-forming thrust events began at
approximately 5 and 2 Ma (Jaswal and others,
1997). Seals include fault truncations and
interbedded shales and the thick shales and
clays of the Miocene and Pliocene Siwalik Group
.
39

40. • Generation and Migration:
Generation of hydrocarbons most likely began
in Late Cretaceous time for Cambrian through
Lower Cretaceous source rocks and again from
Pliocene time to the present for younger
source rocks. The burial-history plots of Law
and others (1998) also indicate that maximum
burial was reached approximately 2 million
and others (1998) also indicate that maximum
burial was reached approximately 2 million
years ago. Even though there were probably
two distinct periods of generation from two
different groups of source rocks, sufficient
source-to-reservoir correlation data were not
available to clearly define separate petroleum
systems. 40

41. Cont............,
• In many oil and gas fields, there are stacked
source and reservoir rocks possibly resulting in
mixing of oils. Migration is primarily over short
distances up dip and vertically into adjacent
reservoirs and through faults and fractures
associated with plate collision and thrusting.associated with plate collision and thrusting.
41

42. 4-Adhi Field
• Introduction:
Adhi Field is a joint venture (JV) between PPL as
operator, Oil and Gas Development Company
Limited (OGDCL) and Pakistan Oilfields Limited
(POL), with working interest of 39, 50 and 11
percent, respectively. Field is located about 70 km
(POL), with working interest of 39, 50 and 11
percent, respectively. Field is located about 70 km
south of Islamabad in the Potwar region.
Exploration at Adhi began in 1956 and continued for
a decade during which four wells were drilled in
1976, a seismic survey was carried out that led to
the drilling of Adhi 5, a discovery well, in 1978,
proving the presence of hydrocarbons. 42

43. • Reservoir Rock:
Sakesar is a fractured reservoir, with negligible
matrix porosity. The production from Sakesar
commenced in1980 and was initially from two
wells i.e. Adhi 5 andAdhi7 . These two wells are
structurally at the same level
• watered-out. The presence of an oil-water
contact close to the lowest perforations is
therefore, plausible, and is assumed at 2, 3, 40
m below seismic datum.
43

44. • Source Rock: The source rock of adhi field is
shale of baganwala formation (M.cambrian).
and shale of Dandot formation (Early Permian).
• And also a clay shale of sardhai formation (
early Permian ) age act as a source rock in adhi
formation.
• Seal Rock: The seal rock for adhi formation is• Seal Rock: The seal rock for adhi formation is
shale of Dandot formation, age is early
Permian. And clayey shale of sardhai formation
, age is early Permian . and also a shale of
mianwali formation act as a seal rock in adhi oil
field.
44

45. 45

46. 5-Balkassar oil field
• Introduction:
The Balkassar oil field is situated in the eastern
Potwar sub-basin, lies on the southern flank of Soan
syncline in Himalayan collisional regime. The area
represents Indo-Pak and Eurasian blocks ofrepresents Indo-Pak and Eurasian blocks of
Precambrian to recent time. Thrusting and folding
of Himalayan, Indo-Pak plate movement and Salt
Range uplift form the structural trap in Balkassar
sub-surface (Balkassar anticline).
46

47. • Reservior Rock:
Paleozoic-Tertiary dominantly marine
sedimentary rocks form petroleum systems in
Potwar and are exposed in Salt Range along the
Frontal Thrust. The cracked carbonates of Sakessar
and Chorgali Formations are the major generating
repositories in Balkassar. The limestones of the
Paleocene Patala Formation also contain good
repositories in Balkassar. The limestones of the
Paleocene Patala Formation also contain good
reservoirs of hydrocarbons. Khewra Formation is
the main potential Cambrian reservoir. Khewra
Formation is generally divided into three units.
The basal unit consists of thin bedded, partly
shaly, fine to medium grained sandstone with thin
clay beds. 47

48. • Cont.........,
These represent the products of arid
environment to marginal marine environment.
The upper and middle units of the formation
are moderately porous and display
intergranular primary porosity, which ranges
from 10% - 12%. The uniform grain size andfrom 10% - 12%. The uniform grain size and
moderate sorting of the sandstone indicates
its excellent reservoir nature . The sandstone
also displays fracture.
48

49. • Source Rock:
Hydrocarbon Development Institute of
Pakistan (HDIP), in collaboration with Federal
Institute for Geosciences and Natural Resources
(BGR) Hanover, Germany have identified a
number of source rock horizons through Infra-
Cambrian to Eocene in the Potwar Sub-basinCambrian to Eocene in the Potwar Sub-basin
and surrounding areas. These investigations
suggest that the organic-rich shales of the
Paleocene (Patala Formation) can be considered
as the main contender for sourcing the Potwar
oil fields.
49

50. Cont..........,
• In Potwar Basin, Patala shales of Paleocene
have proven as the main source rocks. These
organic shales were partly deposited in anoxic
conditions prevailing Paleocene due to
buckling of the basin floor. Pre-Cambrian Salt
Range Formation also contains oil shaleRange Formation also contains oil shale
intervals, which show source rock potential. In
Potwar the shales have average values of TOC
as 1.57 and Hydrogen Index as 2.68 . The oil to
source correlation indicates that most of the
oil produced in Potwar sub basin has been
sourced through Patala Formation.
50

51. • Traps and Seal:
Traps have been developed due to thin-
skinned tectonics, which has produced faulted
anticlines, pop-up and positive flower structures
above Pre-Cambrian salt. The clays and shales of
the Murree Formation additionally give effective
vertical and horizontal seal to Eocene reservoirsvertical and horizontal seal to Eocene reservoirs
wherever it is in contact.
51

52. 52

53. REFRENCES
• Patala-Nammal Composite Total Petroleum
System, Kohat-Potwar Geologic Province,
Pakistan By C.J. Wandrey, B.E. Law, and Haider
Ali ShahAli Shah
• Petroleum geology of Pakistan
By Iqbal B Qadri
53