Basin Introduction :.
General
The Himalayan Mountain Range is the most prominent feature on the physical map of
India. The outer hill ranges (sub-Himalayas or Foothills) of the Himalayas extending
over a distance of more than 1500 km from Jammu in the west to Arunachal Pradesh
in the east separate Indo-Ganga plain in the south from the mighty Himalayan mountain
ranges in the north. Geological surveys of the Foothills were conducted by geologists
from Geological Survey of India (GSI): Medlicott (1864), Oldham (1883), Wadia, (1928),
Auden (1934). Subsequently Oil and Gas commission (ONGC) since its inception in
1956, initiated geological surveys followed by drilling of exploratory wells in
this basin.
Geographic Location of the Basin
Himalayan Foothills basin is a NW-SE aligned basin located in the NW Himalayan Foothills
region. The basin borders with Pakistan to the NW and Nepal to the SE. Northern
and southern limits are demarcated by terrain defining faults namely, the Main Boundary
Thrust (MBT) and the Himalayan Frontal Fault (HFF). Longitude: Latitude:
Physiography and Accessibility
The hill ranges in this belt form a series of WNW-ESE trending hills with intervening
valleys. These hills, mostly constituted of Tertiary rocks rise to about 1800 to
2700 m. beyond the southern slopes of HFF, the area is plain having a cover of alluvium.
Beas, Sutlej, Sira, Gambhar Khad, Gamrola Khad along with their tributaries form
the main drainage system of the area. The basin occupies a zone of varying width
from a maximum of 80 km in Bilaspur area to a very narrow width of ~20 km in the
Kumaun area (figure 2).
The area is well connected by all weather motorable roads and can be approached
by railways also. The Pathankot- Jogindernagar railway line passes through the area.
The nearest international airport is New Delhi, from where domestic flights are
available for Chandigarh and from there the area can be approached by rail and roads.
Basin Category
Prospective (Category III); the basin has indicated hydrocarbon shows that are considered
geologically prospective (figure 3)
Basin Area
The total area of the basin is about 30,300 sq. km.
Age of the Basin & Sediment-thickness
The Himalayan Foreland is an area in which sequences of the order of 10 km thickness
have accumulated. The oldest of these sequences date back to the Palaeocene-Eocene
time. The Himalayan Foreland is the product of tectonic processes that have been
taking place in the orogenic belt in the Cenozoic Era. Deformation and sedimentation
are both active processes in the Himalayan Foreland.
Tectonic History :.
Different Tectonic Zones with in the Basin
Tectonically, the Himalayan foothills forms a part of the Cis-Himalayan foredeep
superimposed on the northern slopes of the Indian platform. The basin consists of
several tectonic blocks demarcated by deep seated faults. During Late Tertiary,
the major Himalayan orogeny brought significant structural deformation and reactivated
some of the deep seated faults giving rise to the thrusted blocks. This enables,
the division of the area into three tectonic belts, namely,
1. The inner tectonic belt
2. The median tectonic belt
3. The outer tectonic belt
The Inner Tectonic Belt
The “Inner Tectonic Belt” is wide and structurally complex. In Himachal and eastern
Jammu foothills, a number of emergent imbricate thrusts have developed, exposing
various sequences of Tertiary sediments (Siwalik, Dharamshala/ Murree and Subathu).
These thrusts are associated with broad synclinal structures in between. Structural
highs corresponding to the related tectonic setup are Sarkaghat, Paror, Rihlu and
Najot, Jwalamukhi and others.
The Median Tectonic Belt
The “Median Tectonic Belt” encompasses the area between the northwest hading Jwalamukhi
and Kishanpur-Mandili thrusts and the south hading Barsar and Deragopipur thrusts.
The major anticlines in this belt are Seri, Suruin-Mastgarh, Balh, Chilli, Cheri
and Changartalai.
The Outer Tectonic Belt
This belt encompasses the structures of the outer foothills. The northern limit
of this belt is marked by the Barsar thrust, and the southern limit by the Himalayan
frontal thrust. The major structures in this belt include the Deragopipur, Bharwain,
Dhionsar, Ramgirdhar and Janauri anticlines.
Adjoining the foothills area, due south are the Punjab plains. Here the tectonic
deformation in Tertiary sediments is minimal which show a clear basinward thickening
due north.
Basin Evolution :.
The Himalayan mountain system is the product of collision between the Indian and
Asian Plates. The timing of collision has been variously interpreted from the KTB
(Jaeger et al., 1989) to about 50 m.y. (Klootwijk et al., 1979). The initial consequence
of this collision resulted in the withdrawal and closure of the Tethys Sea about
50 m.y. ago. Extensive marine sedimentation represented by the Subathu Group in
the Lesser Himalayan province and in the marine sequences of Ladakh terminated in
the early Middle Eocene (Bhatia, 1985). After the closure of the Tethys, deformation
spread southwards across India’s erstwhile shelf. Wells (1983) has provided palaeocurrent
data from the Middle Eocene Kuldana Formation to show that flow into the basin took
place from the west and the north. Flow from the edge of what was India’s shelf
suggests that orogenic processes on the continental margin had reversed the palaeoslope.
Continued motion of the Indian plate after the India-Asia suturing led to a staged
migration of the focus of the deformation across 200-300 km of the marginal area
of the Indian Shield. This changeover of the mode of collision from interactive
continental/oceanic island arc systems to a purely continent-to-continent type has
resulted in intracontinental shortening. Major intracontinental shear associated
with the Central Crystalline Zone has been recognized.
The Himalayan Foreland consists of the Murree/Dharamsala fluvio-deltaic to fluvial
sequences marking the onset of (syn)-orogenic molasses sedimentation. These deposits
of latest Eocene (?) or Oligocene to Early Miocene age underlie the Siwalik Group,
and derived their detritus from the northern uplifts. The initiation of the Himalayan
Foreland appears to be connected to the change in the mode of collision (C-C) and
the initiation of deformation in the margin of the subducting Indian plate.
The Murree/Dharamsala Group extends along the southwestern flank of the Pir Panjal
through Punch and Naoshera into Jammu Hills. Below Dalhousie in Himachal Pradesh,
it is reduced to narrow strip. The main belt expands in width in Himachal Pradesh
below Subathu where they are referred to as Dagshai and Kasauli formations. Further
to the east, the development of these sequences is negligible.
A significant point is that throughout the 11,200 sq. km occupied by the Murree
deposits of Kohat and the Potwar plateau, an unconformity with the Eocene is recognized
by the occurrence in the basal part of the Murree of numerous fragments and pebbles
of the Alveolina limestone which forms the top of the Eocene. This indicates that
the Eocene basin had already been topographically inverted, in parts, and points
towards the presence of new relief in the zone bordering the southern limit of the
Tethys.
In contrast to this stage of the Himalayan Foreland, the area of molasses deposition
expanded considerably 20 m.y. ago. The Lower Siwalik deposits are known to occur
throughout the extent of the western Himalaya as well as in the eastern Himalaya.
The oldest Siwalik sequences are considered to be about 19 m.y. The thickness of
the Kamlial and Chinji Formations of the Lower Siwalik Subgroup ranges from several
hundred to over a thousand meters. These thick fluvial sequences would imply relatively
proximal uplifts to the north. Southward migration in the focus of deformation in
the margin of the shield can be inferred. In the Indus River sections, the sandstones
of the Siwalik Group deposited by ancestral (Indus type) rivers over the past 18
m.y. contain detrital zircons that are only 1 to 5 m.y. older than the depositional
age of the sandstones. Young zircons were inferred to be a component of Himalayan
surface rocks for the past 18 m.y. This led to suggest that a series of uplifted
blocks have been continually present in the Himalaya since 18 m.y. The existence
of 17 m.y. old fan sediments has also been documented at site 718 drilled on the
Bengal Fan by Leg 116. Further, at the bottom of hole 718E, fan sediments of Early
Miocene age were still being penetrated with no evidence of having reached the base
of the fan. This clearly points to the presence of a voluminous sediment source
for the Bengal Fan in the Early Miocene. As a corollary, considerable relief must
have existed in the Himalaya even before the Miocene.
Within the Siwalik Basin, there is yet another remarkable event seen in the form
of thick accumulations of multistoried sand complexes during the Nagri time interval
(10 m.y. to 8 m.y.). Kyanite is an important element of the heavy mineral assemblages
of these sandstones. These sand complexes occur in widely separated area such as
the Potwar plateau, Haritayalnagar and Dehra Dun.
The Upper Siwalik Subgroup spans a time interval of 5 m.y. Cannibalism of the older
molasse sequences indicates interactive tectonics between basin-margin-source are
fold-thrust units. Cannibalism of the older basinal materials from its northern
margins implies a further southward shift in the focus of deformation. Continued
northward motion and the resultant compression in this zone resulted in tectonic
partitioning by growth structures (intrabasinal folding, MBT splays etc.). This
is expressed in fold-thrust related basinal uplifts and tectonically controlled
valley-depressions. The extremely proximal depositional sites have accumulated conglomerates
which have been shown to be time transgressive (about 3 m.y. and younger), and in
many cases consist of clasts predominantly derived from the hanging wall older basinal
sediments.
In most areas of the Foothills belt of the western Himalaya, deformation is an ongoing
process and the outermost anticlines connected to the Himalayan Frontal Fault (HFF)
may be as young as 0.2 m.y. The youngest terraces and fan deposits have also been
uplifted and are being cannibalized presently.
Generalized Statrigraphy :.
Stratigraphically the area is presented by Tertiary sediments unconformably underlain
by Early Cambrian to Precambrian rocks.
The Pre-Tertiary sequence in the Himalayan foothills is mostly composed of dolomitic
limestones, quartzites and shales. The overlying Tertiary sequence is thickest in
the inner foothills and becomes gradually thinner towards southwest. A brief description
of these sediments is given below:
The Pre-Tertiary Stratigraphy of the Simla Krol belt, north of MBT, comprises of
metamorphic and sedimentary rock types of Precambrian to early Paleozoic age. The
Stratigraphy has been drawn from the earlier work, modified with the sub-surface
information.
In sub-surface, granitic basement has been encountered in a few wells, for e.g.,
Saharanpur-1, in southern part of the basin where the sedimentary thickness is very
less.
Pre - Tertiary
Jutogh Group
The group consists of black, carbonaceous, garnetiferous phyllites, slates, quartzites
and dolomites intercalated with biotite schists and hornblende gneisse. The exposures
are known from Lesser Himalayas.
Simla Group
This group comprises of bluish grey slate, micaceous shale, sandstone, quartzites
intercalated with microcrystalline and oolitic limestone. These rocks are exposed
around Simla hills. At places in the field mapping, these have been clubbed together
with Chail Group of rocks which represent slightly higher grade of metamorphism.
Shali Group
This is dominantly a carbonate sequence made up of dolomite, shale, stromatolitic
limestone and occasional magnesite and quartzite. Rocks of Deoban Group and Bilaspur/
Bandla Limestone are considered equivalent to Shali Group. These rocks occur in
tectonic windows under nappe of metamorphic rocks. At places thin Nummulitic outliers
are found on these rocks. These rocks are broadly considered to be homotaxial to
Simla slates. Bandla limestone forms the basement of Subathu sediments mapped in
Bilaspur unit.
Jaunsar Group
This group of rocks is exposed north of Main Boundary Thrust (MBT). It is composed
or low grade metamorphics such as slate, phyllites and quartzites. In the field,
it is divisible into Mandhali, Chandpur and Nagthat formations which are named after
localities in Garhwal.
Mandhali Formation
This formation consists of quartzites, shales, crystalline limestone and marble
interbedded with slates, phyllites, gritty quartzites and bounder beds.
Chandpur Formation
It consists of mainly quartzites, phyllites and tuffaceous slates.
Nagthat Formation
This formation comprises sandstones, grits, quartzites, conglomerates, purple and
green slates and phyllites. The top of the group represents a strong unconformity
followed by a succession of rocks classified as Mussoorie Group.
Mussoorie Group
It can be subdivided into Blaini, Infra-Krol, Krol and Tal Formations.
Blaini Formation
It mainly consists of boulder beds, limestones and shale with characteristics of
a glacial till. The boulder bed consists of dark grey to greenish grey clay matrix
with pebbles of dark slate, greenish quartzite, grey sandstone, green siltstone
and occasionally microcrystalline limestone. Limestones are characteristically pink,
dolomitic and siliceous and grade into pink and purple calcareous shale and slates.
These rocks along with Infra-Krol and Krol are exposed north of MBT.
Infra-Krol Formation
It comprises dark shale, black carbonaceous shales and quartzites.
Krol Formation
Krol formation mainly consists of limestone, often stromatolitic, shale and sandstone.
The limestone is grey to greyish white, dolomitic, cherty and at places microcrystalline.
The shales are red, orange and dark gray in color. The sandstones are dirty white,
poorly bedded with orange stained quartz grains.
Tal Formation
These rocks are composed of calcareous greywacke, carbonaceous shale, micaceous
shale, arkosic quartzite and grey limestone. In the subsurface, it has been identified
in well Mohand-1, where it consists of shale, dolomite and silty shale. Auden, who
pioneered field geological investigations in Krol series, considered these as Permo-Triassic
to Cretaceous in age. This was primarily based on glacial nature of Blaini boulder
bed to represent deposits of early Carboniferous glacial period, which he considered
as clinching evidence. Recently, from the discovery of conodonts in these rocks
in Mussoorie area, a few research workers prefer to assign a Cambrian- Ordovician
age to these formations.
Following a long hiatus, the sedimentary sequence belonging to Tertiary age was
deposited south of the central Himalayan axis. (In contrast, nearly a complete sedimentary
sequence representing whole of Palaeozoic era was deposited and preserved north
of central Himalayan axis). In Simla area, these sediments have been studied in
detail and mapped by geologists of ONGC and the following description is mainly
based on those findings.
Tertiary
Subathu Group
This formation consists of olive green to dark green shales interbedded with thin
limestone bands and coal seams. Rich assemblage of Nummulite, Asilina, Rotalia etc
has been reported. The Subathu Group is assigned Upper Palaeocene to Eocene age.
Subathu sequence represents coastal swamps and shallow to open marine environment
deposits. In subsurface, the identification of Subathu sequence is not documented
with faunal evidence.
Dharamshala Group
The sediments of the Dharamshala Group unconformably overlie the Subathu group.
These sediments consist of claystone, siltslones, calcareous shales and sandstones.
The Dharamshala group is divisible into Lower and Upper Dharamshala. The Lower Dharamshala
sediments were deposited under transitional brackish water environment and upper
Dharamshala mainly represent fluvial system. The equivalent of Dharamshala group
is known as Murree Group in J and K.
Siwalik Group
The Siwalik Group comprises of sandstone, siltstone and clay/claystone alternations
in the lower part, whereas the upper part is represented by conglomerates, pebbly
bands and sandstone lenses. These are broadly divided into Lower, Middle and Upper
Siwaliks, ranging from Middle Miocene to Lower Pleistocene. The sediments were deposited
as channel bars, piedmont bars, floodplain and alluvial fan deposits.
Alluvium
The Alluvium consists of loose sand, silt, clay, pebble, gravel, boulder and kankar.
It unconformably overlies different formations in different areas.
Geological History & Depositional Environment
The basin started with a shallow marine environment which changed to estuarine and
deltaic with time. By mid-Miocene, continental sedimentation marked by fluvial environment
dominated the scene and this set-up has continued to the recent with minor modifications.
The basin had predominantly transversal dispersion pattern controlled by southerly
flowing rivers emerging from the Himalaya and during the Neogene period, a master
stream along the southern margin of the basin drained into the Bay of Bengal. The
fluvial sedimentation in the basin was influenced by tectonism throughout its evolution.
The Early Cambrian to Precambrian limestone forms the base for the Tertiary sediments.
Sedimentation was initiated in the Paleocene time under paralic conditions at the
beginning of transgressive phase in which carbonaceous shale and coal were deposited
followed by shallow marine conditions with the deposition of live green shales and
foraminiferal limestones of Upper Paleocene to Eocene age. The sea regressed thereafter
at the end of Eocene, during which red shales, laminated mudstones, grey, blue siltstones
and purple calcareous sandstones of Dharmsala were deposited under transitional
brackish water environment. The closing phase of marine incursion commenced due
to uplifting in Proto-Himalayan source area and as a consequence, a coastal fluviatile
environment was established.
Deposition of Lower Siwalik started in Middle Miocene associated with Himalayan
orogeny. The northern margin of the basin also got uplifted at this stage and this
axis of deposition shifted southwards, sub-parallel to Himalayan trends.
During Upper Miocene times (middle Siwalik sub-Group), a thick succession of pebbly
sandstones and claystones were deposited mainly by braided and meandering streams
with a concomitant shift of the depositional axis southwards. This sequence is very
thick at places with sediments supply from main provenance from the rising Himalayas.
During Plio-Pleistocene orogeny, the northern part, presently the Foothills area
of the basin was further uplifted and as a result of which conglomerates of Upper
Siwalik sub-Group were deposited as alluvial fans at the foot of mountains. Tectonic
movements of the Himalayas later produced the present topography and it was further
sculptured by Quaternary glacial and interglacial processes with the deposition
of high level river terrace conglomerates.
Petroleum System :.
Hydrocarbon Potential
Two surface shows of oil and several shows of gas, both in surface and in wells,
have been observed in this belt. Occurrence of thick veins of asphalt in limestone
in the localities of Satra, Fatehpur and Jokan (Poonch area) of J&K was reported
as early as 1928 by Geological Survey of India. ONGC geologists investigated the
limestone in Satra in 1964-66, and reported the presence of bituminous veins in
a 90 m thick limestone band.
The other known oil show is near Chomukha village on the eastern blank of Alsed
Khad in Sundernagar area ( Fig. 2). This show is observed in a sandstone bed at
the base of Dharmasala sequence. The rocks are highly crushed, being adjacent to
the MBT. Droplets of light crude oil in cavities and joints of thin limestone bands/lenses
have also been noticed in the Alsed Khad below Chomukha village. This limestone
is of Upper Paleocene to Eocene age (Subathu Formation).
Numerous gas shows have been observed in the median and inner tectonic zones in
Himachal Pradesh and Jammu and Kashmir, the most famous being the gas shows in Jawalamukhi
temple. The gas is mostly methane (87.8%) with small amounts of C02, N2 and O2.
The other main gas shows in this belt include those in Dehar Khad River near Kotla
village, Suruinsar and Mansar lake areas in J&K state and from the flank of Sarkaghat
anticline in Himachal Pradesh. Surface gas shows along anticlinal axis and fault
traces become ubiquitously manifest during rainy season when bubbles of gas escaping
through muddles of collected rainwater become detectable.
As the peak hydrocarbon generation time is also the time of primary migration, mid-Miocene,
which has been shown to be the time of kerogen maturation, is a very significant
and fortuitous time in the process of generation, migration and accumulation of
hydrocarbons in the Himalayan foothills. This time period also coincides with major
orogenic uplift of the Himalayas that caused development of major structural elements
in pre- Siwalik rocks. The folds provided structural traps and the thrusts and faults
could provide pathways for secondary migration of hydrocarbons.
As such the most prospective areas for exploration will be the large structures
in Paleogene belts with thick sediments and the reservoir traps which might be mapped
in the lower Siwalik rocks lying adjacent to or under the Paleogene source sequences
along major thrusts like the Bilaspur Thrust. Large surface anticline adjacent to
belt of Paleogene rocks are also promising areas. On these criteria, the whole of
Tertiary belt in the offered block is promising for hydrocarbon exploration.
The prognosticated resources of the basin are 140 MMT (OIL +OEG). The density of
resources considered is 10,000 T/Km2.
Habitat of Oil & Gas
Litho-Facies
The pre-Tertiary section of the Himalayan Foothills is primarily composed of mixed
clastic carbonate sequence. The sandstone and carbonate reservoir facies generally
have low primary porosity. However, fractures are often observed in this section.
The presence of secondary porosity in the limestone hosting the hydrocarbon may
not be ruled out.
The Lower Tertiary reservoir facies in out crops also have low primary porosity
and fair permeability.
The Upper Tertiary (Upper Dharmasala and Lower Siwalik) reservoir facies have better
development of primary porosity (8 to 15%) and fairly permeable.
Source Rocks
The pre-Tertiary sequences in Himalayan Foothills are mainly lean in organic carbon
and are over mature. The outcrop samples from Vaishnodevi limestone in Jammu & Kashmir
and Bilaspur limestone in Himachal Pradesh contain 0.01 to 0.33% of organic carbon.
The Subathu rocks are the only marine sediments in the stratigraphic sequence present
in the basin. In analogy with the neighboring Kohat-Potwar basin in Pakistan, Subathu
sediments are believed to be source rocks of hydrocarbon in this basin. The Subathu
sediments form Jammu foothills and Himachal Pradesh are characterized by poor to
marginally rich organic carbon content. However, at places Subathu is encouraging
in organic carbon content.
The overlying Dharmsala/Murree and Siwalik sequences represent brackish and fluviatile
sediments deposited in an oxidizing environment and have marginally rich organic
carbon content (0.02 to 1.02%).
Reservoir Development
The rocks which can form good reservoirs in the basin may be limestones and sandstones
present in the sedimentary sequence. The limestones in the exposures are jointed
and fractured and these can act as potential reservoirs in subsurface. These are
most likely in pre-Tertiary sequences and Subathu Formation. The sandstones are
extensively developed throughout the sedimentary sequence with an appreciable thickness.
Sandstones of Subathu, Dharmsala/Murree and Siwalik thus can be good potential reservoirs
in the basin.
Entrapment
Traps of two main types, structural and combination are likely to be present in
this basin. The structural traps include large number of exposed NW-SE trending
anticlines such as Janauri, Bhimbergali, Suruin-Mastgarh, Paror, Sarkaghat, Changartalai,
Bharwain etc.
Further, the chances of structural entrapment in the subthrust block are considerably
high, where the deformation was continuing with the accompanying possible thermal
maturation of source rocks and generation of hydrocarbons.
Alternations of arenaceous and argillaceous lithologies are observed in the entire
Tertiary sequence from Lower Dharmsala onwards which could provide good reservoir
and cap rocks.
Exploration Status :.
Petroleum Division of Geological Survey of India started the exploration activities
for exploration of hydrocarbons in the area. It was considered that the area had
good possibility of locating significant exploitable reserves of petroleum. Surface
oil shows at Chomukha near Sundernagar and a gas show at Jawalaji temple near Jwalamukhi,
in Himachal Pradesh constituted significant hydrocarbon shows. The exploration work
by detailed surveys and investigations was systematically continued by ONGC established
in 1956 as a national E&P Company.
Details of Exploration input.
|
GEOLOGICAL SURVEYS
|
|
Semi-detailed mapping
|
99,163.5 Km2
|
|
Special studies
|
1,931 Km2
|
|
Reconnoitory traversing
|
300Lkm
|
|
AEROMAGNETIC SURVEYS
|
45,000 Km2
|
|
GRAVITY MAGNETIC SURVEYS
|
30,079 Stations
|
|
SEISMIC SURVEYS
|
|
Refraction
|
3510.29 GLK
|
|
Reflection CDP
|
2578.97 GLK
|
|
EXPLORATORY WELL
|
|
Number of wells drilled
|
15
|
|
Meterage
|
61,304.35 m
|
|
STRUCTURAL WELLS
|
|
Number of wells drilled
|
8
|
|
Meterage
|
6,239.25 m
|
The area is covered by detailed, semi-detailed, special studies, reconnoitory traversing
and reconnoitory mapping. 15 Exploratory wells have been dilled in different structures
of the basin with the discovery of two minor gas pools in Lower Siwalik section
above Jwalamukhi thrust. Through this mapping, detailed stratigraphic framework
has been established along with the tectonics of the foothill belt which helped
in projection of subsurface geology.
Geological Survey
Geological surveys by ONGC were carried out in this area since its inception. Detailed
and semi detailed mapping, special studies on sedimentary features like current
bedding, reconnoitory traversing and investigations of oil and gas shows were carried
out. Geochemical samplings were undertaken in Subathu (Eocene) and Lower Dharmsala
(Oligocene) sediments for laboratory analysis. Through this mapping, detailed stratigraphic
framework and tectonics of the foothill belt has been established that helped in
projection of subsurface geology. The geological map is shown in fig 2.
Geolophysical Survey
Aeromagnetic surveys carried out in 1957, gave a broad indications of basin configuration,
which formed the basis for initiation of seismic and gravity- magnetic (GM) surveys
from 1957-58 field season onward. Major part of the basin is covered by GM surveys
(Fig. 3 & 4). Both the maps clearly show that NW/SE Himalayan trend is the dominant
lineament in the basement. However, there is a strong suggestion of NE/SW (Aravali
trend) lineament in the area lying between Kalka and Dehradun. Initially, seismic
surveys conducted in the Punjab plains were of refraction and conventional type
which were followed by more sophisticated CDP surveys during seventies. The foothill
area has been partially covered by CDP surveys.
Exploration Drilling
Exploratory drilling in the basin was initiated with the drilling of well Jawalamukhi-1
(JMI-1) during 1957-58. Two minor gas pools were discovered in the Lower Siwalik
sub-Group section above Jwalamukhi thrust. In the area of the map, three wells have
been drilled. One well, Ramshahr-1 is located in the block under offer. Chari-1
lies on the northern side of the block and Mohand-1 towards the southeastern side
of the area. A total of 15 exploratory wells have been drilled in the Foothill belt.
List of Exploratory Wells Drilled
|
S.No.
|
Well Name
|
Drilled Depth(m)
|
|
1
|
Jawalamukhi-1
|
3067.80
|
|
2
|
Jawalamukhi-2
|
5047
|
|
3
|
Jawalamukhi-3
|
994
|
|
4
|
Jawalamukhi-6
|
1274.19
|
|
5
|
Balh-1
|
4474.55
|
|
6
|
Janauri-1
|
4531.40
|
|
7
|
Janauri-2
|
5027
|
|
8
|
Ramshahr-1
|
2648
|
|
9
|
Suruinsar-1
|
3665
|
|
10
|
Mohand-1
|
5264.4
|
|
11
|
Cheri-1
|
3238
|
|
12
|
Suruinsar-2
|
5448
|
|
13
|
Jawalamukhi-B (JMI-B)
|
6720
|
|
14
|
Nurpur-1
|
4935.50
|
|
15
|
Changartalai-1
|
4968.5
|
Oil & Gas Resources
The total hydrocarbon resources in the Himalayan foothills from Jammu in the west
to UP Himalayas in the east has been prognosticated to be about 150 million cubic
meters of oil & oil equivalent gas (O&OEG). The resources in the Tertiary exposure
areas of Himachal Pradesh are estimated to be around 50 million cubic meters of
O&OEG.