SAURASHTRA OFFSHORE BASIN - Infraline

SAURASHTRA OFFSHORE BASIN

SAURASHTRA OFFSHORE BASIN 1. BASIN AREA : 240,000 Sq. Km. 1.1 BASIN LOCATION MAP : Refer Sedimentary Basin

Map of India in Notice Inviting Offers (NIO)

2. EXISTING DATA BASE

2.1 OFFSHORE SEISMIC DATA 2D : 43672 LKM 3D : 5626 Sq. Km.

Vintage Type Data acquired by Quantum

2002-2003 2D DGH 615 LKM

1981-2003 2D ONGC 27,177 GLK

2001-2003 3D ONGC 3023 Sq. Km.

2001-2003 2D RIL 2634 LKM

1997-2002 2D Essar 2154 LKM

1991 2D OIL (Western Geophysical) 8730 LKM

2002 3D OIL (M/s Veritas DGC) 330 Sq. Km.

2.2 OTHER SURVEYS - Gravity data – 33,306 LKM - Magnetic data – 31,519 LKM - Geochemical Sniffer surveys-4900 LKM - Satellite Gravity Survey

2.3 WELL DATA Number of exploratory wells : 18

Hydrocarbon shows : Gas and oil shows in Middle Eocene to Miocene in 6 wells.

3. BLOCK ON OFFER : 1 Block in Shallow waters

GS-OSN-2003/1

4. BASIN TYPE : Pericratonic Rift Basin. 5. PROVEN SEDIMENTARY SECTION

Age range Thickness (m)

Cretaceous to Recent ~7,000


5.1 GENERALISED STRATIGRAPHIC SEQUENCE

5.2 REPRESENTATIVE GEOLOGICAL SECTION

STRATIGRAPHIC UNITMAX.

THICK.(M)

LITHOLOGY SOURCE RES. SEAL OIL & GAS SHOW

POSTMIDDLE

MIOCENE

MIOCENE

T E

R T

I A R

Y

PALEOCENE

CRETACEOUS

700

900

450

270

OLIGOCENE

EOCENE 1500

MIDDLE

EARLY

LATE

EARLY

LATE

MIDDLE

EARLY

1. TOC - 1-4.8%VRO - 0.3-0.7%TYPE -II & III

V V V V V V

SILTSTONE

SHALE

LIMESTONE

VOLCANICS

LEGEND

DOLOMI TE

V VVVV

MESO-ZOIC

SHOWS

1


6. PETROLEUM GEOLOGY

EXPECTED RESERVOIRS :

(i) Cretaceous sandstone (ii) Eocene-Miocene shelfel carbonates / reefal build up (iii) Tertiary deep water sands (Indus Fan)

EXPECTED SOURCE ROCKS :

(i) Paleocene to Oligocene shales EXPECTED CAP ROCKS : (i) Eocene to Early Miocene shales.

7. EXPECTED PLAY TYPES :

(i) Carbonate buildups (ii) Transpressional rollovers (iii) Pinchouts and wedgeouts

8. INFORMATION DOCKET - CONTENTS

PART A

INTRODUCTION PHYSIOGRAPHY, CLIMATE AND COMMUNICATION STATUS OF EXPLORATION Geological Surveys Geophysical Surveys Exploratory Drilling TECTONIC FRAMEWORK STRATIGRAPHY GEOLOGICAL HISTORY HABITAT OF OIL AND GAS Source rocks

Reservoir development

Entrapment Conditions Hydrocarbon Potential

REFERENCES


LIST OF FIGURES

Fig. No.

Description

1. Index map of Saurashtra basin 2. Physiographic map of Indian offshore 3. Geological map of Saurashtra 4. Bouguer anomaly map of West coast offshore and Arabian sea 5. Structures identified in Saurashtra basin 6. Key wells drilled in Saurashtra offshore and adjacent areas 7. Litholog of well Ss-1 8. Lithologs of wells SSN-1 and S-2-1 9. Lithologs of wells B-107-1 and B-1-1 10. Stratigraphic relationship between wells west of Diu Arch 10A. Litholog of well OS-II-A-1

11. Litholog of well OS-II-D-1 12. Litholog of well OS - II - G – 1 13. Stratigraphic relationship between wells OS-II-A-1, OS-II-D-1 and

OS-II-G-1 14. Stratigraphic relationship among wells SOE-1, SOE-2 and SOE-3 15. Location map of DSDP sites 16. Litholog of DSDP site 219 17. Litholog of DSDP site 220 18. Litholog of DSDP site 221 19. Main tectonic elements of West-coast deep offshore basins 19A. Main tectonic elements of West-coast DEEP offshore basins &

satellite altimeter derived free-air marine gravity field 20. Geological section across Saurashtra basin 21. Seismo-geological section - Saurashtra basin 22. Litho-stratigraphy of Saurashtra basin 23. Influence of Indus fan in Laxmi depression 24. Oil and gas fields in west coast offshore basins 25. Cross plot of hydrogen index Vs tmax in well S - 2 - 1 26. Turbidite in Laxmi depression 27. Stratigraphic wedgeout 28. Carbonate buildup


LIST OF TABLES Table No.

Description

1. Seismic data acquisition and processing parameters, ONGC survey : 1975-94, D lines 1976, 1981 & 1985, BO lines 1986 – 87 and D-94 lines

2. Seismic data acquisition and processing parameters- Western Geophysical survey (1981-82)

3. Seismic data acquisition and processing parameters-oil survey 1991 (Western Geophysical)

4. Acquisition and processing parameters, ONGC survey BO lines (1988), S lines (1976, 80, 82 & 86 – 88), S1 lines (1983), D lines (1994) & DK lines (1995)

5. and processing sequence for 2D seismic survey by DGH in 2002-2003

6. General information of key wells – Saurashtra offshore and adjacent areas

7. General information of DSDP wells 8. Exploratory inputs in Saurashtra Offshore Basin 9. Average Organic Carbon distribution patterns in

Saurashtra offshore wells


PART – B

BLOCK ON OFFER

LOCATION OF THE BLOCK

GS-OSN-2003/1

200

00’

210

00’

220

00’

700 00’ 700 00’

700 00’ 700 00’

200

00’

210

00’

220

00’

0 45 Km.

Scale

D

C

E F

G

AB

GS-OSN-2003/1

S A U R A S H T R A

Drilled Well

EP-1


BLOCK : GS-OSN-2003/1 1. BLOCK AREA : 5,970 Sq. Km (Approx.) 2. WATER DEPTH RANGE : From few meters to 70m 3. EXISTING DATA BASE

3.1 SEISMIC SURVEYS : 2D - 3708 LKM

SEISMIC COVERAGE MAP

3.2 OTHER SURVEYS : Satellite Gravity Surveys

GM Surveys

3.3 WELL DATA Number of Exploratory Well - One ( EP-1 )

GS-OSN-2003/1


4. STRATIGRAPHIC SEQUENCE ENCOUNTERED IN WELL EP-1

5. TWT MAP ON TOP OF EARLY EOCENE

200

30’

200

45’

210

00’

200

30’

200

45’

210

00’

700 15’ 700 30’ 700 45’ 710 00’

700 15’ 700 30’ 700 45’ 710 00’

0 10 Km.

ScaleContour interval 50 Millisec.

S A U R A S H T R A 95010001050110011501200125013001350140014501500155016001650170017501800185019001950200020502100215022002250230023502400245025002550260026502700275028002850290029503000305031003150320032503300335034003450350035503600

95010001050110011501200125013001350140014501500155016001650170017501800185019001950200020502100215022002250230023502400245025002550260026502700275028002850290029503000305031003150320032503300335034003450350035503600

Colour Range

Drilled Well

EP-1

L I M I T

D E P O S I T I O N A L

L I M I T

D E P O S I T I O N A L

TWT

P-1

2300

P-2

S-68

GS-OSN-2003/1

U P

P E

R

M I

O C

E N

E

T O

R

E C

E N

T

AGE Depth (m) LITHOLOGY Brief description

E A

R L

Y

T O

M

I D

. M

I O

C E

N E

OLIGOCENE

EOC

ENE

2600

1200

1400

1600

1800

2000

2200

2400

1000

800

600

400

200

( AGE BOUNDARIES ARE TENTATIVE )

TD 2610 m

Sand : f – c grained.

Sand : f - m grained, loose.

Grey to dark grey shale with minor sandstone

Sandstone with streaks of limestone & shale.

Sandstone & shale with streaks of limestone.Shale : grey to dark greyLimestone with minor shale

Limestone with minor shale & marl

Coal : black

Shale with fragments of volcanic rocks

Clay / claystone : grey, fossiliferous.

Limestone with thin layers of shales

Oil & Gas Shows

Hyd

roca

rbon

s S

how

s in

man

y w

ells

in

adj

acen

t are

as


6. SOME OF THE INTERPRETED PLAY TYPES

A.) Structural Highs

B.) Porosity Pods in Tertiary Carbonates

100 200 300 400 500 600 700 800 900Line S-84

1.5

2.0

2.5

3.0

3.5

TWT

IN

SE

CS.

MID. MIOCENE

EARLY EOCENE TOP

WITHIN MIDDLE EOCENE

SPNW SE

Prospect P-1

S-84S-84

STRUCTURAL HIGH OVER HORST BLOCK ALONG LINE S-84

1.5

TWT

IN

SE

CS.

2.0

2.5

3.0

3.5

Line S-147

MID. MIOCENE

EARLY EOCENE TOP

WITHIN MIDDLE EOCENE

SNW NSESP

Prospect P-1

200 400 600 800 1000 1200

S-147S-147

STRUCTURAL HIGH OVER HORST BLOCK ALONG LINE S-147

GS-OSN-2003/1


BLOCK ON OFFER – CONTENTS

BLOCK : GS-OSN-2003/1

Definition of the Block

Geo-scientific Surveys

- Geophysical Survey

- Exploratory Drilling

Hydrocarbon Prospects

Expected Play Types

Data Package

LIST OF FIGURES

Description

Fig. 1 Index Map of Block GS-OSN-2003/1

Fig. 2 Bathymetry Map

Fig. 3 Bouguer Gravity Anomaly Map

Fig. 4 Magnetic Anomaly Map

Fig. 5 Seismic Coverage Map

Fig. 6 Seismic Section Along Dip Line S-82-1

Fig. 7 Seismic Section Along Strike Line ES-97-01

Fig. 8 Seismic Section Along Dip Line through Well EP-1

Fig. 9 Seismic Section Along Strike Line through Well EP-1 Fig. 10 TWT Map on Top of Basement

Fig. 11 TWT Map on Top of Early Eocene

Fig. 12 Prospects P-1 & P-2 at the level of Top of Early

Eocene

GS-OSN-2003/1


Fig. 13 TWT Map on a Horizon in Middle Eocene

Fig. 14 Prospect P-1 at a level in Middle Eocene

Fig. 15 TWT Map on a horizon in Middle Miocene

Fig. 16 Lithocolumn of Well EP-1

Fig. 17 Structural High over Horst Block Along Line S-84

Fig. 18 Structural High over Horst Block Along Line S-147

LIST OF TABLES

ANNEXURE

Annexure No. Description

I Contents of data package for the block GS-OSN-2003/1

Table 1 List of Seismic lines available for the block

Table 2 Acquisition & Processing Parameters for ONGC survey

S lines (1976, 80, 82 & 86 – 88)

GS-OSN-2003/1

SAURASHTRA OFFSHORE BASIN - Infraline

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