NARMADA, KUTCH & SAURASTRA BASIN

BY:

K.PRAMOD

B.TECH 2’ND YEAR

RAJIV GANDHI INSTITUTE OF POETROLEUM TECHNOLOGY,RAE-BARELI

What is a sedimentary basin?

• A low lying area in the earth crust

• Basically tectonic in origin

• Sediments get deposited and accumulated

► Areal extent of about 1.79 million sq. km.

► So far 26 basins have been recognized.

► In the deep waters beyond 200m isobaths, the sedimentary area has been estimated to be about 1.35 million sq.km.

► The unexplored area has come down to 15% which was 50% in 1995-1996 and the credits goes to DGH

► On the basis of geological prospectivity, the basins of india have been divided into 4 categories

Category 1: Proven commercial productivity

Category 2: Identified prospectivity

► Sedimentary basin with proved occurence of hydrocarbons but from which no commercial production of hydrocarbon has been occurred.

Category 3: Prospective basins► Sedimentary basins with no significant oil and gas shows but which on

geological considerations are considered as prospective.

Category 4: Potentially prospective► Petroliferous basins with uncertain prospects which require basic data to be

generated for prognosis. It includes the basins which bear an anology with similar hydrocarbon producing basins in the world and may be prospective.

KUTCH BASIN

► It forms the north-western part of the western continental margin of India.

► It is bounded by the Nagar- Parkar fault in the North, Radhanpur-Barmer arch in the east and North Kathiawar fault towards the south.

► The basin extents between Latitude 22° 30' and 24° 30' N and Longitudes 68° and 72° E covering entire Kutch district and western part of Banaskantha (Santalpur Taluka) districts of Gujarat state.

► The total area of the basin is about 71,000 sq. km of which onland area is 43,000 sq.km and offshore area is 28,000 sq.km. upto 200 bathymetry.

► The basin is filled up with 1550 to 2500m of Mesozoic sediments and 550m of Tertiary sediments in onland region and upto 4500m of Tertiary sediments in offshore region (Well GKH-1). 

Saurashtra basin

► The basin is located in the northern part of western continental margin of India.

► The onland part of the basin is also known as Saurashtra Peninsula.

► This basin lies north of commercially proven Mumbai Offshore and south of highly prospective Kutch basin.

► The onland part of the basin borders with the commercially proven Cambay Basin on its eastern flanks.

► The deeper offshore Saurashtra borders with the Indus fan (to the abyssal plain of the Arabian Sea)

NARMADA BASIN

► It is the southern-most of the three marginal basins embayed into an arrow graben along the Narmada-Songeo fracture.

► The narmada rift basin crosses it in the Gulf of Cambay region at the widest part of the shelf, south of kathiawar bulge.

The evolution of the western continental-margin basins of India is related to the breakup of eastern Gondwanaland from western Gondwanaland in the Late Triassic / Early Jurassic and the subsequent spreading history of the Eastern Indian Ocean The western margin evolved through early rift and post rift phases of divergent margin development. A series of regional and local horsts and grabens resulted in response to rifting along the dominant basement tectonic trends (NNW-SSE, NE-SW and ENE-WSW). The northernmost part of the western continental margin was the first to be subjected to continental rifting and crustal subsidence in the Late Triassic The opening of the Kutch basin to the north of Saurashtra peninsula coincided with the transgressive phase of the sea onto the coastal areas of other parts of Gondwanaland including the western margin of Indian plate during Jurassic-Cretaceous time (Krishnan, 1960).

KUTCH BASIN:

GEOLOGICAL HISTORY:

Rifting along the Delhi trend and consequent subsidence of the block between the Nagar Parkar hills and the Saurashtra Peninsula in the Late Triassic initiated development of the Kutch Basin.

The basin formed the site for westerly deepening epi-continental sea, probably an extension of the Tethys, in which thick pile of sediments, ranging in age from Middle Jurassic to Early Cretaceous, were deposited in shallow marine to deltaic environments. The sediments were deposited in two major cycles - a Middle Jurrasic transgressive cycle and a Late Jurassic - Early Cretaceous regressive cycle

The Kutch basin is a pericratonic rift basin situated in the western margin of India. Nagar Parkar uplift in the north and Kathiawar uplift (Saurashtra horst) in the south respectively along Nagar Parkar and North Kathiawar faults delimit the E–W rift

GEOLOGY AND TECTONIC EVOLUTION:

The Kutch basin has a comprehensive Mesozoic package. It has about 3000m of sediments ranging in age from the Late Triassic to Lower Cretaceous. The basin was inundated by sea by the Middle Jurassic (Bajocian) times.

The sediment package is predominantly siliciclastic with the carbonate sediments being mostly confined to the Bathonian.

The siliciclastic sediments range from nearshore coarse-grained sands and conglomerates to storm-influenced shallow shelf silts and clays.

The Kutch basin got rifted along this trend. Kutch rifting was initiated in the Late Triassic as indicated by continental Rhaetic sediments in the northern part of the basin(Koshal, 1975). In the early stages of India's northward drift away from Gondwana land, during Jurassic time, the Kutch basin was formed by subsidence of a block.

SAURASHTRA BASIN:

GEOLOGICAL SETTING OF AN AREA:

The Saurashtra peninsula is located in the western periphery of India in the state of Gujarat. Saurashtra is a pericratonic rifted passive margin basin comprising an onshore area of 52,000 km2 and a 20,000 km2 offshore extension into the Arabian Sea.

The peninsula developed by rifting along the three intersecting Precambrian orogenic trends, the ENE–WSW Narmada Son lineament, the west coast fault with the NNW–SSE Dharwar trend and the NE–SW Delhi Aravalli trend,at different stages of evolution of the Indian sub-continent and their subsequent reactivation during the Mesozoic and Tertiary times. Bounded by major faults and rift basins, the northern limit of Saurashtra is marked by the faulted margin of Kutch and the southern coast runs parallel to the extension of Narmada geo-fracture.

The Wadhwan Formation occurs as a marine tongue within an overall deltaic system. The Deccan Trap Formations occupy most of the exposed area of the Saurashtra.

PETROLEUM GEOLOGY:

Expected reservoirs : (i) Cretaceous sandstone. (ii) Eocene-Miocene shelfel carbonates / reefal build up. (iii) Tertiary deep water sands (Indus Fan).  Expected source rocks : Paleocene to Oligocene shales  Expected cap rocks : Eocene to Early Miocene shales.  CATEGORY OF THE BASIN:

Category III (Prospective Basin).

AGE OF THE BASIN & SEDIMENT-THICKNESS:

The oldest phanerozoic rocks in this basin are the Mesozoic rocks exposed in the north eastern part (Dharangdhara Formation) of this basin.

However major part of the Saurashtra Basin (both on land& offshore) is covered by Deccan Traps which have hindered the exploration of Mesozoic Hydrocarbon targets.

Rocks of Early Cretaceous are exposed in the on land part of the Saurashtra Peninsula (north eastern part of the basin). Late Cretaceous – Early Paleocene Deccan Volcanics cover most of the Saurashtra Peninsula and the Tertiary sediments are exposed only on the periphery of the Peninsula.

TECTONIC HISTORY:

Tectonic movements in the Tertiary were milder and cyclic.

After the early Middle Miocene, the western margin as a whole experienced heavy influx of clastics and manifests basinward rapid shift of the shelf over considerably long distance to its present position.

The principle tectonic elements in the offshore region are:

Shelfal Horst-Graben Complex:

lies between the coast and shelf margin trough. The shelf structural assemblage consists of a number of horsts & grabens.

Shelf Margin Trough:

This Is a narrow linear trough elongated parallel to the shelf edge. It lies between shelfal horst-graben complex to the east and Laccadive ridge to the west. 

Laxmi Basin:

This Is located between Laxmi ridge and Laccadive ridge. Consists of a series of pronounced linear magnetic anomalies.Total sedimentary cover in the Laxmi basin varies from 1250m on basement highs to 3000m in the depressions.

Laccadive Ridge:

It is considered as a continental remnant rifted away from the continental margin and reworked by hotspot volcanism. The ridge has a complex system of grabens, half grabens& normal faults. 

Laxmi Ridge:

This Is a narrow elongate ridge in the deep offshore part west of Laxmi Basin. 

Arabian Abyssal Plain:

Is a typical oceanic depression in Cenozoic times through the sea-floor spreading along the Carlsberg ridge. It is consistent with a set of well-pronounced magnetic anomalies characteristic of seafloor spreading. 

NARMADA BASIN:

GEOLOGICAL HISTORY:

Narmada is the southern-most of the three marginal basins embayed into an arrow graben along the Narmada-Songeo fracture.

In the Early Cretaceous,fluvialsedi ments of the Nimar Formation were deposited by a river system flowing along the Narmada lineament.

The valley opened into a rift basin in Late Cretaceous time, and marine sediments were deposited in a progressively deepening environment until the end of the Cretaceous.

Then sedimentation ended abruptly as a result of regional uplift followed by activity that deposited the Deccan Trap in early Paleocene time.

The marine sediments were mostly carbonate and less than I,000ft (300m) thick. This section indicates a slow rate of basin subsidence and uplift of the adjacent horsts.

This period of Late Cretaceous transgression is Synchronous with transgression on the eastern continental margin and the final regression of the Mesozoic sea from Kutch and Cambay basins.

Stratigraphy

of

Kutch Basin

Age of Formations Name of Formations

Miocene till Recent Alluvium FormationMilliolite FormationSandhan FormationKandle FormationKharinadi FormationMittinadi FormationChhasra FormationGodhra Formation

Oligocene Narayansarovar FormationTune LimestoneManiyara Fort Formation

Eocene Sir FormationFulra LimestoneHarudi FormationPanadra FormationJakhaue FormationNaredi Formation

Paleocene Nakhtarana FormationMatanomadh FormationDeccan TrapNaliya FormationBhuj FormationKori Formation

Jurassic Bibat FormationWagad FormationWashtawa FormationKhadir FormationGoradongar FormationKaladongar FormationJhuran FormationJumara FormationJhurio FormationLuna FormationLodai FormationNirona Formation

Precambrian Igneous /metamorphic basement.

Stratigraphy

Of

Saurashtra Basin

Age of formation Name of Formation Lithology

Mesozoic Dharangdhara Formation Wadahawan Formation Deccan Trap Volcanics

feldspathic, argillaceous sandstones with subordinate shales and clays. Coarse to fine grained, cross bedded, conglomeratic, pebbly, ferrogenous, fining upwards sandstones. Shales occur as lenses with carbonaceous matter.

Cenozoics Jafrabad formationNakhtarana Formation Belapur FormationJakhau FormationDiu formationFulra LimestoneTuna Limestone Narayan Sarovar Formation Gaj FormationNavibandar FormationMitti Nadi /Chhasra Formation Dwarka Formation Mangrol Formation

formation is alternating sequence of Limestone / Shale with few quartzitic sandstone layers .

Stratigraphy

of

Narmada Basin

HYDROCARBON POTENTIAL OF KUTCH BASIN:

• The Kutch Basin is a petroliferous basin where one oil and two gas strikes have already been made.

• The gas pools were struck in GK-29A and GK-22C structures in sandstone reservoirs of Palaeocene and Late Cretaceous age at a rate of 1,24,332 m3/d and 2,39,930 m3/d respectively, whereas oil was struck in KD structure in Middle Eocene limestone and siltstone reservoirs at a production rate of 172 BPD at a depth of 1,056-1,097 m.

• Kutch Basin is contiguous to the hydrocarbon-producing Cambay Basin in the east and southeast, Mumbai Offshore Basin in the south, and the South Indus Basin of Pakistan in the North, where several discoveries of oil and gas have already been made.

:

Study of source rock in Kutch basin:► Source rock studies have been conducted on samples from outcrops, on land

wells Banni-2, Nirona-1, Lakhpat-1, Suthri-1 and most of the offshore wells except few.

► The organic matter is of type II and III. The productivity index of the Mesozoic outcrop samples indicates migrated hydrocarbons. The outcrop samples from the western on land part of the basin indicate that Eocene and Oligocene sediments contain type III and type II mixed Kerogens with TOC ranging from 0.54% to 3.45%.

► At present, the Upper Cretaceous sequence is in peak oil generation phase and hence the major phase of oil migration is likely to have started only around 1-2 Ma (Pliocene-Pleistocene). The argillaceous Jhuran Formation of Late Jurassic age has been drilled in only one of the offshore wells i.e. GK29A-1, where shale layers with adequate TOC are buried deep enough to attain maturity

HYDROCARBON POTENTIAL OF KUTCH, SAURASTRA AND NARMADA BASIN:

HYDROCARBON PROSPECTS OF THE SAURASHTRA BASIN:

► The Jamnagar sub-basin of Saurashtra, Gujarat is considered geologically prospective for hydrocarbons by Directorate General of Hydrocarbons (DGH), India. However the major part of the Jamnagar sub-basin is covered by Deccan Traps, hindering the exploration of Mesozoic hydrocarbon targets.

► Microbial analysis revealed high bacteria counts for methane (1.32×106cfu/gm.), ethane (8.50× 105cfu/gm.), propane (6.86×105cfu/gm.) and butane oxidizing bacteria (5.70×105cfu/gm.) in soil samples of Jamnagar sub-basin. The bacterial concentration distribution maps show three distinct anomalies in the study area, indicating hydrocarbon micro seepage at these places.

► Jamnagar sub-basin of Saurashtra has significant sediment thickness below the Deccan Traps and can be considered for future hydrocarbon exploration. The corroboration of adsorbed light gaseous hydrocarbons and hydrocarbon oxidizing bacteria suggests its efficacy as one of the potential tool in surface geochemical exploration of hydrocarbons.

► Two wells of reliance named Dhirubhai-27 and Dhirubhai-33 are established and here gas production is tacking place.

Hydrocarbon prospects of Narmada basin:► Major fields occur on north-south-trending, linear, fault-bounded ridges flanked by

narrow grabens. The reservoir rocks are mainly Eocene and Miocene limestone's.

► North of Narmada lineament, which is mainly a clastic basin, commercial hydrocarbon resources are yet to be proved.

► Because of the short geologic history of the basin, the thinness of sediments, and the complete exposure of the section from basement to top, the Narmada basin is not considered prospective

► Of all the marginal rift basins, this basin has the longest history of deposition, with about 12,000ft (3,600m)of sediments ranging in age from Jurassic to Holocene

► In the lower mid-Jurassic section, marine carbonate and shales were deposited.

1) GEOLOGICAL HISTORY AND TECTONICAL HISTORY OF KUTCH, NARMADA AND SAURASTRA BASIN- DGH.INDIA.COM.

2) HYDROCARBON PROSPECTS IN SUB- TRAPPEAN MESOZOIC DECCAN SYNCLINE, INDIA: EVIDENCE FROM SURFACE GEOCHEMICAL BY C. VISHNU VARDHAN1, B. KUMAR1, C.J. KUMANAN2, DEVLEENA MANI1, AND D. J. PATIL.

3) GEOCHEMICAL ASSESSMENT OF LIGHT GASEOUS HYDROCARBONS IN NEARSURFACE SOILS OF KUTCH-SAURASHTRA: IMPLICATION FOR HYDROCARBONPROSPECTS BY LAKSHMI SRINIVASA RAO*, P., MADHAVI, T., SRINU, D., KALPANA, M.S., PATIL, D.J. AND DAYAL, A.

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