Potential of shale gas in Indian
sedimentary basin
Dr. A M Dayal
Emeritus Scientist
Petroleum Geochemistry Group
Council of Scientific & Industrial
Research
National Geophysical Research
Institute
Uppal Road, Hyderabad 500007
Guar International 17-18 Nov 2015, Jaipur
For the rapid economic growth, country need large amount
of energy in any form.
It is extremely
6,000
important to estimate
the magnitude of
energy requirements
and the fiscal deficit,
subsidies and interest
and revenue shortfall
in last five years.
Fiscal deficit in last five years
F
i 5,000
s
c
a 4,000
l
3,000
In (Rs)
D
e
f 2,000
i
c
i 1,000
t
Deficit In % of GDP
0
Year
Guar International 17-18 Nov 2015, Jaipur
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.
Exponential jump in subsidies and interest payments
3000
2500
2000
1500
1000
500
0
2011-2012
2010-2011
2009-2010
2008-2009
2007-2008
Guar International 17-18 Nov 2015, Jaipur
Year
Unconventional sources of energy are increasingly important
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.
Guar International 17-18 Nov 2015, Jaipur
Major sources of energy in India
Coal
53%
Oil
31%
53%
8%
Natural Gas
8%
Hydro electric 5%
6%
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%.
Guar International 17-18 Nov 2015, Jaipur
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.
Guar International 17-18 Nov 2015, Jaipur
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.
Guar International 17-18 Nov 2015, Jaipur
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.
Guar International 17-18 Nov 2015, Jaipur
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
Guar International 17-18 Nov 2015, Jaipur
Distribution of unconventional gas all over the world (TCF)
Region
North America
Latin America
Europe
USSR
Middle east
Africa
Asia
Pacific countries
South Asia
Total
Shale Gas
3,840
2,116
548
627
2,547
274
3,526
2625
0
16,103
Tight Gas
1,371
1,293
431
901
823
784
353
1254
196
7,406
CBM
3,107
39
275
3,947
0
39
1,215
470
40
9,051
Guar International 17-18 Nov 2015, Jaipur
Shale gas potential in various countries. Besides US, Europe
is the next continent working on shale gas exploration.
Guar International 17-18 Nov 2015, Jaipur
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
Guar International 17-18 Nov 2015, Jaipur
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
Guar International 17-18 Nov 2015, Jaipur
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. %
0.50 to 1.00 wt. %
1.00 to 2.00 wt. %
>2.00 wt. %
Non source
Fair
Good
Excellent
TOC decreases with maturity.
Based on kerogen type it could be oil prone, gas prone or oil and gas
prone.
Guar International 17-18 Nov 2015, Jaipur
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.
Guar International 17-18 Nov 2015, Jaipur
2. Exploration drilling and analysis of cores for geochemistry and
petrophysical properties.
Guar International 17-18 Nov 2015, Jaipur
3. Understanding the
extent
of
shale
gas play with the
help of pilot wells,
seismic
interpretation and
log correlation.
Guar International 17-18 Nov 2015, Jaipur
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.
Guar International 17-18 Nov 2015, Jaipur
5. Geochemical analysis and the
study of stress regime helps in
Rock Eval 6 for pyrolysis and oxidation
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.
Guar International 17-18 Nov 2015, Jaipur
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.
Guar International 17-18 Nov 2015, Jaipur
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.
Guar International 17-18 Nov 2015, Jaipur
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.
Guar International 17-18 Nov 2015, Jaipur
Horizontal drilling and hydraulic fracturing
Guar International 17-18 Nov 2015, Jaipur
In India there are 28 sedimentary basins which have been divided in four
categories based on the potential of hydrocarbon.
Category I Basin
Cambay
Assam Shelf
Bombay Offshore
Krishna Godavari
Cauvery
Assam-Arakan
Rajasthan
Area (Sq km)
53,000
56,000
116,000
52,000
55,000
60,000
126,000
Category II Basins
Kutch
Andaman-Nicobar
Category III Basins
Himalayan Foreland
Ganga
Vindhyan
Saurashtra
Kerala Konkan
Mahanadi
Bengal
48,000
40,000
Area (Sq km)
17,000
186,000
162,000
80,000
94,000
69,000
89,000
Guar International 17-18 Nov 2015, Jaipur
Category IC Basin
Karewa
Spitti-Zanskar
Satpura-Rewa
Narmada
Deccan Syneclise
Bhima-Kaladgi
Cuddapah
Pranitha-Godavari
Bastar
32,000
4,000
22,000
46,000
70,000
273,000
9,000
39,000
15,000
5,000
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.
Guar International 17-18 Nov 2015, Jaipur
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.
Guar International 17-18 Nov 2015, Jaipur
*In Thrust Belt
Karewa Gas Seeps
Palaeozoic
Shales
Palaeozoic /Mesozoic
Karakoram Shales*
Mesozoic Shales
Kashmir
Ladakh
Neoproterozoic
Sirban Shales*
Jammu
IERT
Eocene
Subathu Shales*
EGI
MPRG
Palaeozoic
Zanskar Shales*
Geological Map of Jammu and Kashmir with
Potential Shale Formations for Shale Gas Exploration
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.
Guar International 17-18 Nov 2015, Jaipur
4. Damodar Basin:
In the Damodar basin shales of
significant thickness have been
reported in the following formations:
i.
ii.
iii.
iv.
v.
vi.
Bansa-Chandia
Pali-Tikhi
Raniganj
Barakar
Talchir
Mahendragh
The technically recoverable gas in the basin is 30 Tcf.
Guar International 17-18 Nov 2015, Jaipur
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.
Guar International 17-18 Nov 2015, Jaipur
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
Holocene to
Pleistocene
L Miocene
Pleistocene
Early to Middle
Miocene
Oligocene
Eocene
Formation
Alluvium
Lithology
Sand, clay
Thickness
100m
Cuddalore
sandstone
Sandstone, limestone, coal
300-600m
Sandstone, shale, limestone,
coal
Shale, sandstone, limestone
Shale, sandstone, limestone
1190m
Shale, sandstone, limestone
Sandstone, shelly limestone
Carbonaceous shale, limestone
Limestone, black shale
700m
2700m
2700m
400m
Sandstone, shale
1090m
Paleocene
Pondicherry
Late Cretaceous Ariyalur
Trichinopoly
Early
Dalmiapuram
Cretaceous
Jurassic
Sivganga
1060m
1150m
Guar International 17-18 Nov 2015, Jaipur
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.
Guar International 17-18 Nov 2015, Jaipur
9. Cuddapah basin:
Major shale formations are Nandayal, Tadpatri, Owk and Cumbum shale in
the basin. Recoverable shale gas is 75 Tcf.
Guar International 17-18 Nov 2015, Jaipur
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 Subbasin
iii. Barmer-Sanchor Subbasin
Guar International 17-18 Nov 2015, Jaipur
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.
Guar International 17-18 Nov 2015, Jaipur
Water contamination
There 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.
Feed
water
pH
8.5
Calcium(Ca)
22
Magnesium(Mg) 6
Flow back
water
(ppm)
4.5-6.5
22,000
2000
Sodium(Na)
Iron(Fe)
Barium (Ba)
Strontium(Sr)
Manganese(Mn)
57
4
0.22
0.45
1
32,000
500
200
4,000
4
Surphate(SO4)
5
32
Chloride
Methanol(CH4)
20
--
1,20,000
2,000
TOC
--
6,000
Guar International 17-18 Nov 2015, Jaipur
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.
Elements
Ba
Ca
Fe
Mg
Sr
TDS
TSS
COD
Frac 1 (ppm)
7.75
700
200
16
5
6,000
490
1,814
Frac 2 (ppm)
2,000
5,000
11
1.9
1,300
9,000
48
570
Frac 3 (ppm)
3,000
14,000
52
5
7000
175,000
415
600
Guar International 17-18 Nov 2015, Jaipur
Frac 4 (ppm)
4,000
31,000
135
7
2,000
248,000
330
2,000
Monitoring and fracking for shale gas exploration includes following:
1.
2.
3.
4.
5.
6.
7.
Regulatory compliance by local authority
Social acceptance by people staying in the area
Identify sensitivities like contamination of shallow water aquifer
Design appropriate monitoring strategy by independent agency
Baseline monitoring for seismicity to observe effect during hydraulic fracturing
Operational monitoring include treatment of flowback water, water treatment
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.
Guar International 17-18 Nov 2015, Jaipur
Complete Schematic of Shale gas system
Public concern about shale gas:
1. What area will be affected?
3. How long the drilling will continue?
5. Financial benefit for the local community?
2. When will be the drilling start?
4. Will the fracking will be 24x7?
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.
Guar International 17-18 Nov 2015, Jaipur
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.
Guar International 17-18 Nov 2015, Jaipur
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.
Guar International 17-18 Nov 2015, Jaipur
Thank you for kind listening
Guar International 17-18 Nov 2015, Jaipur