The document discusses the Bombay High oilfield located offshore of Mumbai, India in the Arabian Sea. It describes how the oilfield was discovered in 1964-1967 by a joint Russian-Indian exploration team mapping the area. The Bombay High field supplied 14% of India's oil needs and accounted for 38% of domestic production, with operations run by India's Oil and Natural Gas Corporation (ONGC) exploiting reservoirs ranging from fractured basement to middle Miocene carbonates.

1.  Siddharth K.
 Smruti S.R.
 Sudhanshu G.
 Swapnil Pal
 Tarun K.
 Yash V.

2.  Bombay High is an offshore oilfield 160 kilometres
(99 miles) off the coast of Mumbai, India. The oil
operations are run by India's Oil and Natural Gas
Corporation (ONGC).
 Bombay Bombay High field was discovered by a
Russian and Indian oil exploration team during
mapping of the Gulf of Khambhat (earlier Cambay)
in 1964-67.
 It supplied 14% of India's oil requirement and
accounted for about 38% of all domestic production
as per data available till 2004.

4.  A Russian and Indian oil exploration team that was mapping the Gulf of
Cambay in 1965 in a seismic exploration vessel called "Academic
Arkhangelsky" discovered the Bombay High oilfield.
 ONGC geophysicist M Krishnamurthy headed the Indian team which was
attached with the Russian Offshore seismic expedition.
 ONGC had a contract with "Technoexport" of the then-USSR for seismic
support.

5.  The first ever momentous application of velocity analysis was on Bombay
high. In 1971-72, interval velocity studies indicated presence of limestone
reservoir in the structure.
 In 1982, a small group of geophysicists was asked to work for the first
time in the Development Geology group (Bombay Offshore) to help solve
the geologic problems associated with field development and production.
 A few wells drilled later on confirmed the seismic predictions of the
synergist group and this resulted in significant upward estimate of in-place
reserves and in suitable modification of the injection wells locations.
 In 1997, acquisition of seismic data in Bombay offshore through Ocean
Bottom Cable (OBC) with dual sensors was the watershed in the use of
latest tools in ONGC.

6.  Here, gamma-ray, resistivity, neutron porosity, and velocity (Vp) well-log
data sets from three vertical wells, viz. Well-A, Well-B, and Well-C are
shown in the figures. The wells, located in the Bombay High oilfield in the
western offshore basin (Fig. 1) are separated by a distance of
approximately 10 km.
 Logs of all three wells represent subsurface sections of approximately 500
m below the sea floor. Velocity log data (in units of m/s) were generated
from the sonic log.
 Data were sampled at 0.15 m and a total of 3280 data points in each log of
all three wells were obtained.

8. Figure 2: gamma-ray log, well-a1, well-a2, well-a3, repectively
Shale (sand) formations show high (low) gamma-ray intensity. Since we are
interested in identifying reservoir rocks (which are non-shaly), identification of
boundaries between different subsurface formations in well-log data becomes
necessary.

9. Figure 3: resistivity log, well-b1, b2, b3 respectively.
Hydrocarbon-bearing formations are characterized with high resistivity compared to
those of non-hydrocarbon bearing formations which is represented by scalograms of the
resistivity logs

10. Figure 4: neutron porosity logs. well-c1, c2, c3 respectively.
Study of the scalograms of the neutron porosity logs of Well-A (Fig. 4c1), Well-B (Fig.
4c2) and Well-C (Fig. 4c3) show high positive coefficients at different depths
corresponding to the decrease in neutron porosity.

11. Figure 5: velocity logs, well-d1,d2,d3
Velocity logs generated from sonic logs measure the interval transit time of sound
waves in the formations. As expected, velocities are usually low for the reservoir rocks
(lime stone and sand stone) when compared to shaly formations.

12.  Bombay High is One of the six sedimentary
basins on Western Continental Margin , i.e.
I. Kutch
II. Saurashtra
III. Bombay offshore
IV. Konkan
V. Lakshadweep
VI. Kerala
 Bombay offshore basin is the largest with an
arial extent of 120,000 km2 .

13.  An intra cratonic basin.
 southern extension of Cambay basin and encompasses the
Gulf of Cambay and adjacent shelf part of the Arabian sea.
 result of faulting in the Deccan trap basement during Upper
Cretaceous.
 This basin is divided into several tectonic units such as - -
Cambay Gulf Shelf to the north
- Dahanu depression to the south
- Bombay Ratnagiri shelf occupying
central and southern part of

14.  developed on divergent passive continental margin
 Three-structural units of carbonate dominant stratigraphy with three
contiguous major depressions.
 clastic domain follows from Mumbai coast towards Arabian Sea:
 Shelfal horst-graben structure
 Kon-comoria depression
 kon comaria ridge
 Lakshmi Laccadive depression
 Lakshmi Laccadive ridge
 Arabian sea

15. Thickness (meter) Formation Age
1700 Chinchini Miocene
377 Tapti (S1 silt sandstone) Miocene
500 Mahim (Bombay high) Miocene
370 Daman Oligocene
314 Mahuva (Heera, Mukta) Oligocene
300 Pipavav (Diu, Bassein) Eocene
618 Jafrabad (Panna, Plaeocene
Devgarh)
Deccan trap Cretaceous
Metamorphosed Precambrian
basement rocks

16.  A hiatus is present between the formation of Metamorphosed
basement –Deccan trap, Deccan trap Jafrabad, Jafrabad-
Pipavav, Pipavav Mahuva and Mahuva- Mahim.
 part of Mahuva formation of Miocene age.
 consists of few meters thick limestone formations separating
from each other by thin layers of shale formations.
 NNW-SSE trending doubly plunging anticline with a faulted
eastern limb having a throw of about 100 Meters.

17.  Mumbai high is divided into two blocks.
1.Mumbai High North (MHN)
2.Mumbai High South (MHS)
 The low permeability zone divides the Mumbai high north and
south.
 There is a 15 meters wide fault between north and south
 The estimated initial oil-in-place (OIIP) in Mumbai high north
and south is 1659 MMt

18.  The L-III limestone is the major reservoir in the field, which
contains 94% of the proved reserves
 Other hydrocarbon producing reservoirs are L-I, L-II and S1.
Oil and gas accumulation is found in Basal Clastics and
fractured Basement also.

19. Petroleum System
Introduction  Bombay offshore basin accounts for nearly
two thirds of the annual petroleum
production of India. The mature source
rocks are present in the lower Eocene
Paleocene Panna formation. Further,
marginally mature potential source rocks
are within the Oligocene in Tapti- Daman
and within Neogene in Deep Continental
shelf and deeper part of the basin also
exist. Hydrocarbons have been discovered
in multiple reservoirs in this basin, ranging
from fractured basement to middle
Miocene.

20. Petroleum System map
Regional structure and
selected oil and gas
fields.

21. Total Composite
Petroleum System
Important elements Source Rock
which constitutes
 Panna formation of Palaeocene-Early
Petroleum System
Eocene is main source rock of crude oil
formation. Panna formation spread over the
entire Mumbai offshore basin. Besides
Panna formation, coral reefs are the source
rocks as well as reservoirs.
 Panna formation Total Organic Carbons
(TOC): 0.5- 20.4 %
 Thermal gradient is 3 degree per 100 feet.
 The source rocks contain mixed type-II and
type-III kerogens.

22. Total Composite
Petroleum System
Important elements Reservoir rock
which constitutes  Limestone is the main reservoir. Limestone is
Petroleum System basically Micrite, Biomicrite and chalky type.
They posses mainly primary and secondary
porosity.
 Average Porosity range: 15- 35%
 Average Permeability: 10 mD to 1 Darcy
 In the Bombay-High area, oil and gas is
produced from fractured basement through
middle Miocene reservoirs, with the most
prolific being the platform carbonates such as
the lower Miocene L-III limestone.
 Other rocks are of Mukta, Baseein, Daman,
Panna and Mahuva formation in Tapti Daman
block.

23. Total Composite
Petroleum System
Important elements
which constitutes
Cap rock
Petroleum System  Shale is mainly cap rock in Mumbai high.
But somewhere carbonates are also present
as cap rocks wherever tight limestone is
formed. E.g.: Bassein Reservoir.

24. Total Composite
Petroleum System
Important elements
which constitutes
Seal
Petroleum System  In the Bombay offshore and Kutch areas,
the most likely seals are an extensive series
of thick middle to upper Miocene shales. In
the Cambay Graben, interbedded Paleocene
through middle Miocene shales provides
seals for the various reservoirs.

25. Burial history chart
Generalized stratigraphy
of Bombay-Cambay-
Kutch area:

26. Total Composite
Petroleum System
Important processes
which constitutes
Trap formation
Petroleum System  Anticlinal reversal & fault closures are
mainly trap. Structure within anticlinal
reverse is mostly developed by drape
sandstone. Trend of fault closures are ENE-
WSW.

27. Total Composite
Petroleum System
Important processes
which constitutes
Generation-Migration-Accumulation
Petroleum System  Generation and expulsion adjacent to the
Bombay-High area may have occurred as
early as middle Miocene and continued, or
began again, in the Pliocene.
 Burial-history data indicate peak generation
most likely occurred during the late Miocene
and early Pliocene.

28. Total Composite
Petroleum System
Events chart:
Generation-Migration-
Accumulation

29. • Discovery
• In early 1960’s, a Russian seismic ship Academic
Arkhangelsky started exploration in the Mumbai
offshore basin.
• Regional geophysical surveys were conducted by this
seismic vessel in the area.
• The oil field of Bombay High was thus discovered
during the mapping of Gulf of Khambat in 1964-67.

30. • ONGC first started drilling in Bombay High with the
drillship Sagar Samrat in 1973.
• First offshore well was sunk in Feburary 1974.
• The field was put on production in May 1976.
• Production from this field was responsible for rapid
growth of the country’s total crude oil production in
1970’s and 1980’s.

31. • Cumulative production from the Bombay High field has
exceeded 2 billion barrels of Oil (BBO) and 3 trillion
cubic feet of Gas (TCFG).
• Estimated Initial oil-in-place (OIIP) in Mumbai High
North and South is 1659 MMT.
• Up till 2004, Oil field of Bombay High accounted for
about 38% of the entire domestic production and
supplied 14% of the oil requirement.

32. • A major fire on 27th July, 2005 destroyed the Mumbai
High North platform.
• The north platform used to produce 110,000 barrels of
oil every day ( a seventh of the country’s oil).
• Rebuilding the platform cost an estimated amount of Rs
1200 crore.

33. • The Bombay High oil field reached its peak production
level in 1998 with 20 MMT an year.
• The quantity of oil produced at Bombay High has been
on the decline since 1990’s due to field GOR and water
cut.
• 1.6 billion $ programme is planned by ONGC to
improve the oil recovery from the field.

34. • Intense exploration and development activities in the
basin have resulted in significant discoveries of several
oil and gas fields:
 Heera
 Panna
 Bassein
 Neelam
 Mukta
 Ratna

35. • ONGC envisages a total crude oil production of 202.42
MMT by 2030.
• It aims to improve the recovery rate by 40% by 2040.
• ONGC has floated a tender for the acquisition,
processing and interpretation of 1975 sq km or 4C-3D
seismic data in the Mumbai High area.
1. 1600 sq km in Mumbai High field
2. 375 sq km in Heera field.

36.  The study of Geology gives an idea about the
formation, stratigraphic sequence and present
condition of the Bombay High oilfield.
 Study of petroleum system also provides
information about generation and expulsion
adjacent to the Bombay-High area which may
have occurred as early as middle Miocene and
continued, or began again, in the Pliocene.
 Burial-history data indicate peak generation
most likely occurred during the late Miocene
and early Pliocene.

37.  During the years, with the development of
geophysics, ONGC has used modern
methodologies like synergists approach and
acquisition through ocean bottom cables
resulting in a clearer subsurface image and
better estimate of in-place reserve

38.  CHANDRASEKHAR, E. AND RAO, E.V., 2012, Wavelet Analysis
of Geophysical Well-log Data of Bombay Offshore
Basin, India, Mathematical Geosciences, Springer-Verlag
 NANDA, N.C., 2002, Petroleum Geophysics in ONGC, India - A
memoir, Geohorizon, SPG India
 Directorate General of Hydrocarbons - Mumbai Offshore Basin
(http://www.dghindia.org)
 Wikipedia – Bombay High
(http://en.wikipedia.org/wiki/Bombay_High)
 www.onepetro.org
 www.offshore-technology.com/projects/mumbai-high
 http://www.ongcindia.com/specrep1.asp?fold=special&file=special1.
txt
 http://www.upstreamonline.com/hardcopy/news/article1263483.ece

39. Thank you