potential of shale gas in indian sedimentary basin dr. a m dayal emeritus scientist petroleum...

Potential of shale gas in Indian sedimentary basin

Dr. A M DayalEmeritus Scientist

Petroleum Geochemistry GroupCouncil of Scientific & Industrial ResearchNational Geophysical Research InstituteUppal Road, Hyderabad 500007

Guar International 17-18 Nov 2015, Jaipur

For the rapid economic growth, country need large amount

of energy in any form.

2011-2012 2010-2011 2009-2010 2008-2009 2007-20080

1,000

2,000

3,000

4,000

5,000

6,000

In (Rs)

Deficit In % of GDP

Year

Fiscal Deficit

Fiscal deficit in last five years

It is extremely

important to estimate

the magnitude of

energy requirements

and the fiscal deficit,

subsidies and interest

and revenue shortfall

in last five years.


2011-2012 2010-2011 2009-2010 2008-2009 2007-20080

500

1000

1500

2000

2500

3000

Year

Exponential jump in subsidies and interest payments

Government is paying subsidies in various form including

oil and gas. But subsidies and interest are more than

double than interest we are paying which is alarming.


There is concern that conventional oil resources will not be able to meet the growing energy requirements.

The increasing gap between supply and demand for energy has forced to explore and develop unconventional resources of energy.

Tight gas, coal bed methane, under ground coal gasification and shale gas are unconventional gas resources.

In future gas consumption will increase and will be main factor for the economic performance and strategic stability of any country.

Unconventional sources of energy are increasingly important


Major sources of energy in India

Coal 53%

Oil 31%

Natural Gas 8%

Hydro electric 5%

Nuclear 2%

Renewables 1%

31%

The oil/gas constitute 39 % of our demand of energy while the major

source of energy is 53 % of coal. Other sources constitute 8%.

53%8%

6%


In 2008, USA was running short of gas and the price was10$/mcf

Production of Shale gas changed the economy of USA and continues to do so. The present price of gas in USA is 3.7 $/mcf.

Shale gas present production takes care of 30% of the USA requirement. In last two years the electricity charges has been reduced drastically due to cheaper fuel as shale gas.

A successful shale gas rock is mostly composed of quartz and carbonate minerals. The brittle nature of shale allows fracking and enhanced permeability for larger amount of shale gas production.


BEIJING, April 18, 2014 (Reuters) -

PetroChina, Asia’s largest oil and gas producer plans to spend more than 1.6 billion $ on shale gas this year which is three times of its over the past few years.

There is good competition between PetroChina and Sinopec.

PetroChina feels that Sinopec Corp is near a breakthrough by announcing a commercial finding.

PetroChina has increased its 2015 shale gas output target from 1.5 to 2.6 billion cubic metres (bcm). That would be 2% of China's total natural gas.

Since around 2010, PetroChina has spent about 482.39 million$ total on pilot shale drilling.


Now the question is what is shale rock:

Shale is a sedimentary rock deposited as muds in tidal flats and

deep water basins.

During the deposition there could be

accumulation of organic matter in the form

of algae, plant, and animal derived organic

debris.

Shales contain 95 percent of the organic

matter.

However, this amounts is less than one

percent by mass in an average shale.


Carbonaceous shale occurs at

different time period from 2.7 to

2.5 Ga, 2.0 to 1.7 Ga and 800-600

Ma.

Increase of carbonaceous shale

deposition reflect:

1. Increased of oceanic

hydrothermal fluxes

2. Anoxia on continental shelves

3. Disrupted ocean currents


Region Shale Gas Tight Gas CBMNorth AmericaLatin AmericaEuropeUSSRMiddle eastAfricaAsia Pacific countriesSouth AsiaTotal

3,8402,1165486272,5472743,5262625016,103

1,3711,29343190182378435312541967,406

3,107392753,9470391,215470409,051

Distribution of unconventional gas all over the world (TCF)


Shale gas potential in various countries. Besides US, Europe is the next continent working on shale gas exploration.


Geological parameters for shale gas evaluation are:

Thickness and areal extent

Type and richness of organic matter

Thermal maturity

Mineralogy, faults and fractures

Gas content and gas storage

Adjacent water bearing formations


Role of geochemistry in shale gas assessment is:

i. Geochemical analysis using TOC, Rock Eval pyrolysis and visual kerogen analysis.

ii. Geochemical modelling of hydrocarbon generation and retention.

iii. Organic richness.

iV. Kerogen type

V. Thermal maturity


Organic richness is measured by Total Organic Carbon analyser (TOC) and expressed as wt. % of rock. Based on TOC the grouping of source rock for shale gas is as follows:

<0.50 wt. % Non source0.50 to 1.00 wt. % Fair1.00 to 2.00 wt. % Good>2.00 wt. % Excellent TOC decreases with maturity.

Based on kerogen type it could be oil prone, gas prone or oil and gas prone.


Shale gas Exploration Technology

The shale gas exploration has following steps:

1. Selection of basin and seismic study to know the extent and thickness of shale in the geological formation.


2. Exploration drilling and analysis of cores for geochemistry and petrophysical properties.


3. Understanding the

extent of shale

gas play with the

help of pilot wells,

seismic

interpretation and

log correlation.


4. Quantification of

shale gas by

studying the

adsorption and

desorption

studies on the

cores to measure

Langmuir volume

and gas content

with change of

pore pressure.Guar International 17-18 Nov 2015, Jaipur

4. The petrophysical

evaluation and reservoir

characterization is

important to evaluate

the shale gas reserve.

Porosity and

permeability are

important measurement

for shale gas

exploration.


5. Geochemical analysis and the

study of stress regime helps in

designing the well completion,

drilling horizontal wells and

selecting proper perforation

technique.

6. Rock Eval pyrolysis system is

an analytical equipment to

measure the S1, S2, HI, OI, TOC,

Tmax, type of kerogen etc.

Rock Eval 6 for pyrolysis and oxidation


7. The data acquired

during the process,

from drilling to

completion and

fracturing can be used

to predict the

performance of shale

gas production for

future, using numerical

reservoir simulator.


8. The ultimate aim is to increase the productivity index. This method

helps to gain vertical connectivity amongst various gas bearing

layers and allow easy connectivity.


Hydraulic Fracturing:

Hydraulic fracturing stimulation is the most extensively accepted tool for the

development of shale gas reservoirs. This is due to the fact that shale reservoirs

have very tight nature with low permeability and to make them flow at an

economical rate stimulation by hydraulic fracturing is necessary.


Horizontal drilling and hydraulic fracturing


In India there are 28 sedimentary basins which have been divided in four categories based on the potential of hydrocarbon.

Category I Basin Area (Sq km) Category IC Basin

Cambay 53,000 Karewa 4,000 Assam Shelf 56,000 Spitti-Zanskar 22,000 Bombay Offshore 116,000 Satpura-Rewa 46,000Krishna Godavari 52,000 Narmada 70,000Cauvery 55,000 Deccan Syneclise 273,000Assam-Arakan 60,000 Bhima-Kaladgi 9,000Rajasthan 126,000 Cuddapah 39,000Category II Basins Pranitha-Godavari 15,000Kutch 48,000 Bastar 5,000Andaman-Nicobar 40,000

Category III Basins Area (Sq km) Himalayan Foreland 17,000 Ganga 186,000 Vindhyan 162,000 Saurashtra 80,000 Kerala Konkan 94,000 Mahanadi 69,000 Bengal 89,000 32,000


1. Assam Arakan basin is prospective basin for shale gas exploration.

Good shale formation has been reported from this basin.

Based on shale formation ~100 Tcf gas is estimated in this basin.


2. Spiti, Kumaun, Kashmir , Karewa and Zanskar basin

The main sub basins in

Himalayan region are Kashmir,

Zanskar, Spitti and Kumaun.

Carbonaceous shales samples

were collected from these

basins.

60 Tcf gas is estimated in these

basins.


IERT

MPRG EGI

NeoproterozoicSirban Shales*

Eocene Subathu Shales*

Mesozoic Shales

PalaeozoicShales

Palaeozoic /MesozoicKarakoram Shales*

PalaeozoicZanskar Shales*

Karewa Gas Seeps

Geological Map of Jammu and Kashmir with Potential Shale Formations for Shale Gas Exploration

Jammu

KashmirLadakh

*In Thrust Belt

3. Cambay Basin:

The Cambay Rift Basin has total area of about 53,500 sq. km. Shales at

Mehsana-Ahmedabad, Tarapur, Broach and Narmada are under study for the

TOC, type of kerogen and maturity level.

Rough estimate is 250 Tcf of shale gas.

3.1 Shales in Cambay basin:

Shales formations associated

with the lignite mines in Gujarat

have been reported from

Tadeshkwar, Surat; Rajpardi,

Bharuch; Panandhro, Kutch;

Madh, Bhuj and Surkha,

Bhavnagar.

Some of these shales has been analysed in our lab and

geochemical data suggest good source for shale gas.


4. Damodar Basin:

In the Damodar basin shales of

significant thickness have been

reported in the following formations:

i. Bansa-Chandiaii. Pali-Tikhiiii. Raniganjiv. Barakarv. Talchirvi. Mahendragh

The technically recoverable gas in the basin is 30 Tcf.


5. Krishna Godavari Basin:

The Krishna Godavari Basin is a proven petroliferous basin in the east

coast of India . The basin contains about 5 km thick sediments.

Technically recoverable resources are estimated to be about 130 Tcf.

Major formations are:

1. Raghavapuram Shale 1100 m thick

carbonaceous shale. The organic

matter is Type III.

2. The Palaeocene Palakollu Shale has

good potential for shale gas.

3. Vadaparru Shale of Lower Miocene

with 4% TOC and Type III kerogen

has potential for shale gas.


6. Pranhita-Godavari Basin:Pranhita-Godavari basin has good number of shale formations and could be very good source for shale gas.

Recoverable gas will be 60 Tcf.

7. Cauvery Basin:

The Cretaceous-Cenozoic Cauvery basin covers an area of 9,100 sq km

in south eastern India is another basin for shale gas.

Recoverable gas is 75 Tcf.

Age Formation Lithology ThicknessHolocene to Pleistocene

Alluvium Sand, clay 100m

L Miocene Pleistocene

Cuddalore sandstone

Sandstone, limestone, coal 300-600m

Early to Middle Miocene

Sandstone, shale, limestone, coal

1190m

Oligocene Shale, sandstone, limestone 1060mEocene Shale, sandstone, limestone 1150m Paleocene Pondicherry Shale, sandstone, limestone 700mLate Cretaceous Ariyalur

TrichinopolySandstone, shelly limestoneCarbonaceous shale, limestone

2700m2700m

Early Cretaceous

Dalmiapuram Limestone, black shale 400m

Jurassic Sivganga Sandstone, shale 1090m


http://3.bp.blogspot.com/-51mhcTgTW1s/TdE1NV2ZKBI/AAAAAAAABIk/2JBCqrlLKpI/s1600/cauvery+shale+gas+eia.jpg

8. Vindhyan Basin:

Organic rich shales from Proterozoic Vindhyan basin have been

reported at many formations. Study of these shales is very important to

understand the maturity, type of kerogen and total organic content.

The Vindhyan basin

formations are exposed in

three sectors (Chakraborty,

2006):

1. Rajasthan sector

2. Bundelkhand sector

3. Son valley sector.


9. Cuddapah basin:Major shale formations are Nandayal, Tadpatri, Owk and Cumbum shale in the basin. Recoverable shale gas is 75 Tcf.


10. Rajasthan Basin

The Rajasthan Basin comes under the Category – I basin and presently

producing largest amount of hydrocarbon.

Estimated recoverable gas is 100 Tcf.

Rajasthan Basin has

been divided into three

Sub-basins:

i. Jaisalmer Sub-basin

ii. Bikaner- Nagaur Sub-basin

iii. Barmer-Sanchor Sub-basin


Some of the important points for shale gas exploration with Indian perspective:

1. Cost of drilling and completing will be higher in India. This is due

to almost no infrastructure and government support to private

players.

2. Indian government does not offer fiscal incentives.

3. In USA and Canada it is mandatory to disclose the substantial and

significant information for each wellbore drilled and this

information is available on public database for other exploration

companies.

4. Lack of widely shared information in India makes it difficult for

the efficient independent operator to exploit resources.Guar International 17-18 Nov 2015, Jaipur

Hydraulic Fracturing (Water Requirement):

1. The drilling and hydraulic fracturing of a single horizontal well may

require 4 to 6 million gallons of water.

2. After hydraulic fracturing, the pressure barriers such as frac plugs

are removed, and flowback water is collected at the wellhead. 15 to

35% water comes as flow back water. This water needs treatment,

before disposal and refract.

3. Composition of frac fluid consists of sand and water and additives.

The additives include biocides, corrosive material, inhibitors,

scavengers, friction reducers and surfactant.

4. Once the well begins to produce gas, this water is referred as

produced water and is recovered throughout the life of the well.


Feed water

Flow back water (ppm)

pH 8.5 4.5-6.5Calcium(Ca) 22 22,000 Magnesium(Mg) 6 2000

Sodium(Na) 57 32,000Iron(Fe) 4 500Barium (Ba) 0.22 200Strontium(Sr) 0.45 4,000Manganese(Mn) 1 4

Surphate(SO4) 5 32

Chloride 20 1,20,000Methanol(CH4) -- 2,000

TOC -- 6,000

Water contaminationThere are two questions about the water. 60% of the fracturing fluid remains with shale formation. 40% water comes back as flowback water.

On the basis of the study of 233 drinking-water wells across the shale-gas region of Pennsylvania, (Boyer et al.,) no major influences from gas well drilling or hydro-fracturing on nearby water wells were reported.

Compared with the pre-drilling data reported in that study, only one well showed changes in water quality (salt concentration). These changes were noticed within days after a well was hydro-fractured less than ~460 m away.


Elements Frac 1 (ppm) Frac 2 (ppm) Frac 3 (ppm) Frac 4 (ppm)Ba 7.75 2,000 3,000 4,000Ca 700 5,000 14,000 31,000Fe 200 11 52 135Mg 16 1.9 5 7Sr 5 1,300 7000 2,000TDS 6,000 9,000 175,000 248,000TSS 490 48 415 330COD 1,814 570 600 2,000

Studies have been carried out to estimate the risk of groundwater contamination with hydraulic fracturing fluid.

The study concluded that changes induced by hydraulic fracturing could allow adjective transport of fracturing fluid to groundwater aquifers in <10 years

We can observe with available data from US that the contamination after every frac is increasing which needs treatment before disposal.


Monitoring and fracking for shale gas exploration includes following:

1. Regulatory compliance by local authority2. Social acceptance by people staying in the area3. Identify sensitivities like contamination of shallow water aquifer 4. Design appropriate monitoring strategy by independent agency5. Baseline monitoring for seismicity to observe effect during hydraulic fracturing6. Operational monitoring include treatment of flowback water, water treatment 7. Post abundant monitoring like disposal of used water in the nearby channel

Pros and Con for shale gas

Pros: Shale gas is game changing transition fuel, providing security of supply, local employment, reduced energy cost and reduced greenhouse emissions.

Cons: Shale gas is an extreme energy that is associated with toxic and radioactive contamination of water supplies, air pollution, earthquakes and climate change.


Complete Schematic of Shale gas system

Public concern about shale gas:

1. What area will be affected? 2. When will be the drilling start?3. How long the drilling will continue? 4. Will the fracking will be 24x7?5. Financial benefit for the local community? 6. Source of water for hydraulic fracturing?

Public feels that irrespective of good working practice the shale gas operation will involve industrialization of the country side and it will affect local person. Partially it is true.

If there is pollution incident there will be the local people who will have to live with it, but chances are vary rare if monitoring by third party is available to local residence.

Fracking specific concern:

Minor Earthquake (2.5 to 3.5)

Fracture opening up the surface for releasing of shale gas

Well casing bursting are only 1% but it does effect local community.

Contamination of shallow water aquifers will effect local community but only in rare cases,

Surface spill of fracking fluid, oil and chemicals to be monitored by independent agency.

Environmental challenges and government support

The main difference between the shale gas development and

conventional natural gas development is the horizontal drilling

and large volume of hydraulic fracturing.

Fracking generates micro seismicity of the order of 3 to 3.5 on

Richter scale, which in case of mud house in the village may

create minor damage.

Higher natural gas price, advances in hydraulic fracturing and

horizontal multilateral drilling have made shale gas wells more

profitable. Guar International 17-18 Nov 2015, Jaipur

In fact shale gas releases more green house gases than the

conventional as it is mainly composed of methane which is powerful

green house gas. But compared to CO2 it stays in the atmosphere

one tenth of time .

The present announcement from the energy minister is quite

acceptable for the industry, which is profit sharing and also you have

freedom to explore conventional gas and oil as well as shale gas, Coal

bed methane, shale oil or even coal.


At present we are importing 20% of our gas and 65% of oil

requirement which constitute 6% of GDP. Though present energy

minister is taking good steps to reduce the import of coal.

With such a large fiscal deficit it is necessary to develop the

alternate source of energy for the energy security of our country

like solar energy and wind energy.

It is necessary to setup research institute for shale gas research

with the financial support from the oil companies profit.

For the required economic growth of our country it is necessary to

be 100 % indigenous energy with no import in any form.


Govt. plan to auction 69 blocks for the conventional and non-

conventional exploration. With low oil prices many oil companies

from western world will be participating for these blocks.

It also proposes several financial incentives for NOCs, including

Income tax and customs exemption, along with reduced royalty to be

paid on shale gas. Present policy allows to use technical capabilities in partnership with foreign companies.

The report also stresses the need for India to expand its natural gas pipeline infrastructure. The Government will have to create a favourable atmosphere to address the landowners, and oil and gas companies, in view of land acquisition.


Thank you for kind listening


potential of shale gas in indian sedimentary basin dr. a m dayal emeritus scientist petroleum...

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