Bombay High is an offshore oilfield located 160 km off the coast of Mumbai, India. It was discovered in 1964-1967 and is operated by ONGC. It supplied 14% of India's oil needs and accounted for 38% of domestic production until 2004. The field is located in the Bombay offshore basin and produces from limestone reservoirs of Miocene age. It has produced over 2 billion barrels of oil and 3 trillion cubic feet of gas to date. A major fire in 2005 destroyed the Mumbai High North platform, costing $1.2 billion to rebuild. ONGC continues exploration and production activities in the area through seismic surveys.

2. Introduction
*Bombay High is an offshore oilfield 160 kilometres (99
miles) off the coast of Mumbai, India,in about 75m of
water of The Arabian Sea.
*The oil operations are run by India's Oil and Natural
Gas Corporation (ONGC).
*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 followed by a
detail survey in 1972.

3. *Here,the structure is a “North-northwest
to South-southeast” trending doubly
plunging Anticline with a faulted East
Limb,65km long & 23km wide & is the
most probable reason to call it “BOMBAY
HIGH”
*It supplied 14% of India's oil requirement
and accounted for about 38% of all
domestic production as per data available
till 2004.

5. GEOPHYSICS
 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.

6. Data Processing &
Interpretation
*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 solve the
geologic problems associated with field development and
production.
*A few wells drilled later on confirmed the seismic predictions .
*In 1997, acquisition of seismic data in Bombay High offshore
through Ocean Bottom Cable (OBC) with dual sensors was the
watershed in the use of latest tools in ONGC.

7. *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.

9. 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.
Figure 2: gamma-ray log, well-a1, well-a2, well-a3, repectively

10. 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

11. 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.

12. 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.

13. •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 .

14. *An intra cratonic basin.
*It is the 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

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,
Devgarh)
Plaeocene
Deccan trap Cretaceous
Metamorphosed
basement rocks
Precambrian

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.
*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

17. Bombay offshore basin
accounts for nearly two thirds
of the annual petroleum
production of India.
Regional structure and selected oil and
gas fields.

18. Source Rock
Panna formation of Palaeocene-Early 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.
Important elements which
constitutes Petroleum System

19. Reservoir rock
*Limestone is the main reservoir. Limestone is
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
*Other rocks are of Mukta, Baseein, Daman, Panna
and Mahuva formation in Tapti Daman block.

20. Cap rock
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.
Seal
• 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.

21. Generalized stratigraphy
of Bombay-Cambay-
Kutch area:

22. •After Discovery Regional geophysical surveys were
conducted by seismic vessel in the confirmed reservoir
area.
•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.

23. •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.
•The north platform used to produce 110,000 barrels of
oil every day ( a seventh of the country’s oil).

24. •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

26. • A major fire on 27th July, 2005 destroyed the Mumbai High
North platform.
• The raging fire that gutted an ONGC oil-drilling platform in
The Bombay High oil field area was caused when an ONGC
vessel “MSV Samudra Suraksha” sent to pick up a sick
worker at the giant platform.
• This mishap resulted in serious oil leakage ,engulfing the
platform & vesssel in a major infeno.
• The damage to “Samudra Suraksha” was extensive but not
enough to sink it.
• Rebuilding the platform cost an estimated amount of Rs
1200 crore.
• Death :10 Missing :14 Rescued:361 Total:385

28. •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.

29. *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.