Potential Shale Gas Basins of India

Possibilities & Evaluations

Dr.V.K.Rao

Conventional Oil/Gas Exploration

In pursuit of conventional Oil/Gas Exploration

over the years,Geologists regarded Shales as:

Cap rock by virtue of their impermeable nature

and compactness thus acting as good seal

Source Rock by virtue of the richness of

organic material content, its maturity ,generation

potential and geographic spread over large

areas

Gauging Shale Gas reservoirs

Methane in shales is generated from the transformation of organic material by bacterial(biogenic) and geo-chemical (thermogenic) processes

The gas so generated gets stored by multiple mechanisms as free gas in micropores/microfractures and as adsorbed gas on the internal surfaces

Thus shale gas is a combination of sorbed gas and micropore gas

The challenge in these accumulations is not of finding it BUT to exploit it commercially

Thus it is more of technological challenge which has been met by innovative hydraulic fracturing and multi-lateral horizontal drillingtechniques.

USA has emerged as the pioneer in developing and using this technology for commercial production of shale gas.

Geological parameters for Shale gas

evaluation

Thickness & areal extent

Organic matter type & its richness

Thermal maturity

Mineralogy,Faults & Fractures

Gas content /Gas Storage

Adjacent water bearing Formations

India-Likely acolyte of shale Gas revolution

Rapidly growing Gas markets

India has high Natural Gas prices

Increasing dependancy on LNG imports

Nascent CBM industry

Widening Demand-Supply gap

Rising Energy Consumption

Rising economic growth

Potential Shale Gas Basins

• : Potential

• Cambay

• Assam-Arakan

• Gondwana

• Vindhyan

• Rajasthan

• Bengal

• Krishna-Godavari

• Cauvery84

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C

B

Cambay Basin

Narrow elongated rift

Basin extensively

explored petroliferous

basin

Sanchor-Patan Block

Ahmedabad-Mehsana

Block

Tarapur-Cambay Block

Broach-Jambusar Block

Narmada-Tapti Block

Shales in Stratigraphy

• Tarapur Fm(Up.Eocene-

Oligocene)

• Kalol Fm(Mid.Eocene)

• Younger Cambay Shale

Fm(Lr.Eocene)

• Older cambay Shale

Fm.(Paleocene-

Lr.Eocene)

• Olpad Fm.(Paleocene)

Cambay Shale Fm.

Source:DGH

Formation Thickness(m) TOC (%) VRo (%) Kerogen Type

Olpad 340-2700 1.5-4.0 0.75 II & III

Older Cambay

Shale

500-1900 1.5-4.0 0.75-0.85 II & III

Younger

Cambay Shale

520-1500 1.00-4.0 0.75-0.85 II & III

Kalol 200-300 0.75 II & III

Tarapur 60-400 0.53

Shale characteristics of Cambay Basin

Prognosticated Resource Potential of 90 TCF is estimated

Assam-Arakan Basin

• Assam Shelf

• Naga-Schuppen Belt

• Assam-Arakan Fold

belt

• Zunki Schuppen Belt

• Ophiolite Complex

• Naga Metamorphic

Complex

Shales in Stratigraphy

Formation Thickness(m)

TOC

%

VRo % Kerogen

Type

Up.DisangGp.

2000-3000 0.69-4.0 0.90-1.94 II & III

Kopili >500 1.0-6.2 0.92-1.44 II & III

Jenam 900-1200 2.5-4.5 0.64-1.20 II & III

Bhuban 800-1000 No data 0.90-1.00

No dataBokabil 400-1000

Shale characteristics of Assam-Arakan Basin

Prognosticated Resource Potential of 55 TCF is estimated

Gondwana Basins

(South Rewa Basin)

• Intracratonic rift Graben Basin

• Criss crossed by a number of ENE-WSW trending Faults

• Lr. & Up. Gondwana sediments are present .

• Barakar and Raniganj Fms. Consist of coal seams and massive shales /sandstones

• Deccan Trap outpouring during Late Cretaceous -Paleocene

Age GROUP Formation Thick-ness (m) Generalised lithology

Recent UP.

GONDWA

NA

Alluvium

Cretaceous to Paleocene Deccan Traps Basalt and Dolerite

Unconformity

Late Cretaceous Lameta 50 Sandstone cake, clays Limestone,

Mart.

Unconformity

Early Cretaceous Bansa Chandia 100 Sandstone, Conglomerates, clays,

shales and Chert

Unconformity

Late Traissic Parsora 450 Sandstone, Mudstone

Middle-Early Triassic LR.

GONDWA

NA

Pali-Tihki 450-600 Mudstone, shale & sandstone

Unconformity

Raniganj 800-1250 Sandstone, Shale, Clays, Coal

Barren Measures 140-600 Sandstone, Red clays

Early Permian Barakar 175-900 Sandstone, grey shales and coal

Umaria Marine Bed 3-5 Fossiliferous sandstone and clays

Unconformity

Talchir 15-400 Sandstone & Shale,

Manendragarh Marine Bed Green Shale & Sandstone

Unconformity

Precambrian Basement Granite, Gneiss, Schist, Phyllites

Shales in Stratigraphy of South Rewa Basin

Geological section along NW-SE trend of South Rewa Basin

Formation Thickness(m) TOC

%

VRo % Kerogen

Type

Raniganj 800-1250 1.06-

18.40

0.40-0.60 III

Barakar 170-900 1.06-

14.72

0.40-0.60 III

Shale characteristics of South Rewa Basin

CHANDRAPUR

ASWARAOPETA

BHADRACHALAM

ASIFABAD

ASP-1

0 30 KM

Scale

SIRONCHA

BHUTARY

+ + +

+++

+

++ +

+

+

+

+

+

+++

++

+

+

+

+++

+

+

+

++

+ + +

+

++

+ + ++ + +

++

+ + + ++ + + +

++

+

+

+ + ++

++ +

+ ++ +

+

+

++ +

++ + + + + +

++

+ + ++ +

+

+

+ + +

++

+ ++

+

+

++ +

+

+

++

+

++

+ +++

CHINTALAPUDI

NORTHWESTERN SECTOR

CENTRAL SECTOR

SOUTHEASTERN SECTOR

NORMAL / REVERSE FAULT

WRENCH FAULT

+

ANTICLINAL AXIS

SYNCLINAL AXIS

BASEMENT

PG-ONN-2001/1

Gondwana Basins

(Pranhita-Godavari Basin)

Intracratonic Rift Basin trending WNW-ESE

Three Sub Basins are identified:

-Eastern Albaka

-Central Pakhal

-Western Chandarpur

BASEMENT+

SANDSTONE SHALE /

CLAYSTONE

COAL

AGESUPER

GROUPFORMATION

LIT

HO

LO

GY

PALEOCENE -

CRET.

JURASSIC

TRIASSIC

LO

WE

R

GO

ND

WA

NA

PERMIANBELLAMPALLI

BASEMENTPRECAMBRIAN

TALCHIR

BARAKAR

JAI PURAM

POTAMADOGU

MANER

MALERI

TARVAI

KOTA

DECCAN TRAP / LAMETA

THICK.

(m)

CHIKIALA / GANGAPUR

KUDUREPALLI

KHANAPUR

V V VV V

+ + +

1

1.

UP

PE

R

GO

ND

WA

NA 400

600

900

1200

150

600

200250

350

600

300

400+

Stratigraphy in Pranhita-Godavari Basin

Formation/

Group

Thickness

(m)

TOC

%

VRo % Kerogen

Type

Lower

Gondwana

Gp.

400-550 6.41% 0.67 III

Upper

Gondwana

Gp.

900-1100 No Data

Shale characteristics of Pranhita-Godavari Basin

Vindhyan Basin

• Peri-Cratonic basin

located in the central

part of Indian massif

Main Tectonic

Features are:

• Great Boundary Fault

• Bundelkhand massif

• Son-Narmada Geo-

fracture Zone

Shales in Stratigraphy

• Binita,Nimbahera

&Suket shales

• Rewa, Ganorgarh and

Sirbu shales

• Chakaria Olive,

Hinolta and Pulkova

shales

WEST VINDHYAN EAST VINDHYAN

GROUP SUB

GROUP

FORMATION THICKNESS(M) FORMATION THICKNESS(M)

UPPER

VINDHYAN

BHANDAR SIRBU SHALES 250 SIRBU

SHALES

85

SAMARIA 30 -

GANURGARH 75 GANURGARH 45

REWA UPPER REWA 150 UPPER REWA 55

BIJAIGARH 35

LOWER

VINDHYAN

SEMRI SUKET 30 CHAKARIA 320

NIMBHERA 150 PULKOVA 210

BINOTA 100

HINOTA 120

Shales in Vindhyan stratigarphy

Formation Thickness(m) TOC

%

VRo % Kerogen

Type

ChakariaOlive shale

185 0.60-1.04

No Data

II & III

Hinota shale 90 0.56-3.89 II & III

Rewa shale 225 0.07-0.40 II&III

Pulkova shale 210 35.0-37.85 II & III

Suket shale 100 0.04-0.37 No Data II & III

GanurgarhShale

75 No Data

Shale characteristics of Vindhyan Basin

Cauvery Basin

• Intracratonic rift basin located between two cratonic masses viz: Indian peninsula and Sri Lankan Massif

Main Tectonic elements are:

• Ariyalur-Pondicherry sub basin

• Kumbhkonam-Madnam-Portonovo High

• Tanjore-Tranquebar sub basin

• Pattukottai-Mannargudi-Karaikal High

• Nagapattinam sub basin

• Vedarniyam High

• Pattukuttai-Manargudi high

• Ramnad-Palk Bay sub basin

• Mandapam Ridge

• Gulf of Mannar sub basin

• Vedarniyam – Tiruchirapally terrace

Shales in Stratigraphy

• Sattapadi Shales in

Uttatur Group

• Kudavasal shales &

Portnovo Shales in

Ariyalur Group

• Komarakshi Shales in

Ariyalur Group

• Karaikal Shales in

Nagore Group

Geological Section across Cauvery basin

Isopach and Shale disposition

Sub Basin Thickness(m)

Approx;

TOC

%

VRo % Kerogen

Type

Ariyalur-Pondicherry

1500 0.31-2.78 1.15 II & III

Tranquebar 2000 0.31-4.76 0.65-0.79 II & III

Nagapattinam 1500 1.68-1.89 0.45-0.34 II & III

Mannar 2000 1.50-1.75 1.0-1.12 II & III

Shale characteristics of Cauvery Basin

Other Prospective Basins

• Krishna-Godavari

Basin

• Bengal Basin

• Rajasthan Basin

Summary

• Shale gas Exploration in India is in nascent stages

• An anology with USA shale Gas basins implies that India could have significant shale gas potential in its major sedimentary basins

• Shale Gas production could be a “Game changer”in energy mix

• In order to assess the shale gas resources basic shale gas specific data requires to be generated through laboratory studies and well data in major shale gas prone basins

Summary

• ONGC has already initiated the process and 1st

Shale gas exploratory well is under drilling in

Bengal basin.

• Initiatives being taken by Govt. of India through

DGH & MoPNG to have international multi task

ventures is a welcome step in this direction

• We are awaiting for the 1st bid round of shale

gas blocks proposed to be offered by MoPNG

by the end of 2011.