Seismic interpretation and well logging techniques

1. Guided by
Prof. L. Mahesh
Bilwa
PRESENTATION
ON
SEISMIC INTERPRETATION AND WELL
LOGGING TECHNIQUES

2.  AIMS AND OBJECTIVES
 INTODUCTION
 PETROLEUM BASINS OF INDIA
 PETROLEUM SYSTEMS ELEMENTS AND PROCESSES
 GEO-PHYSICAL EXPLORATION IN OIL EXPLORATION
 SEISMIC METHOD
 SEISMIC SURVEY
 WELL LOGGING AND ITS TOOLS
 WELL LOG INTERPRETATION
 SEISMIC INTERPRETATION
 CONCLUSION
 REFERENCES
CONTENTS

3. AIMS AND OBJECTIVES
The aim of the work carried out is to know about the seismic
interpretation and well logging techniques employed in hydrocarbon
exploration.
The objectives of this works were :
 To know the principles and working of seismic interpretation.
 To study the well log section and interpretation for further
understanding of the interested pay horizon.
 To bring out the relationship between the different litho-units
and petroleum system present in the area supported collected data.

4. METHODOLOGY
Planning of the work.
 Collection data from ONGC expert
Lab work
 Petroleum exploration and various methods involved
 Preparation of final report

5. • Petroleum and natural combustible gas have been
known to man since Antiquity, long before our Era.
• Petroleum production on a large industrial scale,
however, was started only a little more than one
hundred and forty years ago.
• Petroleum is a naturally occurring, yellow-to-black
liquid found in geologic formations beneath the
Earth's surface, which is commonly refined into
various types of fuels.
• Petroleum is recovered mostly through oil drilling.
• Seismic method is one of the important geophysical
methods used in the petroleum exploration.
• One of the oldest and most used methods that
depend on the geophysical properties of rocks is
subsurface well logging.
INTODUCTION

6. PETROLEUM BASINS OF INDIA
 Sedimentary basins are regions of the earth of long-term subsidence creating
accommodation space for infilling by sediments.
 So far, 26 basins have been recognized and they have been divided into four
categories based on their degree of prospectivity as presently known.
 There are total 26 sedimentary basins in India, of which 7 sedimentary basins are
the major importance for Hydrocarbon reserves. They are
 Assam Shelf
 A&AA FB
 KG Basin
 Cauvery Basin
 Rajasthan Basin
 Cambay Basin
 Mumbai Offshore

7.  The Krishna –Godavari basin, located on the east coast of India between
Visakhapatnam town in north and Ongole town in south.
 Covers an area of 28,000 km2onland and
extends into the Bay of Bengal covering
an area of 24000 km2 up to 200m isobaths
and additional 18000 km2 up to 2000 m
isobaths.
 Well Data
 Number of Exploratory wells on
ONLAND -375
OFFSHORE – 182
Conti…

8. Krishna – Godavari Basin

9. PETROLEUM SYSTEMS AND PETROLEUM BASIN OF
INDIA
 Certain conditions come
together for oil
accumulations to
develop known as
petroleum system.

10. Petroleum system elements
 Source Rock - A rock with abundant hydrocarbon-prone organic matter
 Reservoir Rock - A rock in which oil and gas accumulates
 Porosity - space between rock grains in which oil accumulates
 Permeability - passage-ways between pores through which oil and gas moves
 Seal Rock - A rock through which oil and gas cannot move effectively (such as
mudstone and claystone)
 Migration Route - Avenues in rock through which oil and gas moves from
source rock to trap
 Trap - The structural and stratigraphic configuration that focuses oil and gas into
an accumulation.

11. Petroleum System Processes
 Generation - Burial of source rock to temperature and pressure regime sufficient to
convert organic matter into hydrocarbon.
 Migration - Movement of hydrocarbon out of the source rock toward and into a trap
 Accumulation - A volume of hydrocarbon migrating into a trap faster than the trap
leaks resulting in an accumulation.
 Preservation - Hydrocarbon remains in reservoir and is not altered by
biodegradation or “water-washing”.
 Timing - Trap forms before and during hydrocarbon migration.

12. Cap Rock
 In late Jurrasic to Upper Creatceous sequence, the regional cap is provided by
Raghavapuram shale and Paleocene blastic trap.
 In Paleocene – Eocene sequence, the regional cap is provided by the widespread
impervious unit Bhimanapalli Limestone.
 In the younger Mio-Pliocene sequence, the Godaveri clay provides regional cap.
Traps
 The seismo-geological data indicate that the entrapment of hydrocarbons occurs
in small to medium sized structures.
 Anticlinal structures are the traps for lower Eocene reservoirs.

13. Source rocks:
 Vadaparru-Ravva shale is the main source rock.
 Palakollu-Pasarlapudi shale of upper Paleocene age have a fair to good source rock
potential.
 Krishna/Gopalli- Konukallu the potential source rocks are Krishna /Golapalli formation.
 Kommugudem-Mandapeta fluvial regime is very good source rock.
Reservoir Rocks:
The reservoir rocks occur in arenaceous sequences of different formations ranging in age
from Permo-Triassic to Pliocene, except a few local accumulations in carbonates and
volcanic.

14. Geo-physical exploration for oil and Natural Gas
 Exploration is the art of searching for the purpose of
discovering natural resources. Exploration occurs in all non-
sessile animal species, including humans.
 Hydrocarbon exploration is the search for oil and natural gas
by petroleum geologists and geophysicists.
 The areas which are thought to contain hydrocarbons are
subjected to gravity, magnetic and seismic surveys on the
regional scale are carried out.

15. SEISMIC METHOD
 Seismic method is one of the important geophysical methods used in the petroleum
exploration.
 The term Geophysics means Physics of the earth or the study of the physical
properties of the earth.
 Principles : Seismic prospecting depends upon the difference in wave velocity and
transmission pattern of elastic waves through different rock formations. The waves
are generated by explosives, hammering big nails, weight dropping techniques
 Prospecting based on the analysis of elastic waves generated in the earth by artificial
means. The elastic waves produced during sudden disturbance are called as Seismic
wave. These seismic waves are recorded using the instrument, Seismograph and the
record obtained is Seismogram. It is an important geophysical prospecting applied in
oil and natural gas deposits, deep ground water exploration, depth estimation,
geotechnical problems.

16. SEISMIC SURVEY
 Set of geophysical methods of exploration based on a study of artificially induced
waves of elastic vibrations propagating in the Earth crust.
 Seismic exploration, broadly speaking, creates a picture of the subsurface by
recording vibrations as they bounce back from geological formations.
 The resulting data is called seismic lines.

17. o One of the oldest and most used methods that depend on the geophysical
properties of rocks is subsurface well logging.
 These methods are particularly good when surface outcrops are not
available.
 Well logs are results of several geophysical measurements recorded in a
well bore. They consist of key information about formation drilled i.e.
 To identify the productive zones of hydrocarbon.
 To define the petro-physical parameters like porosity, permeability,
hydrocarbon saturation and lithology of zones.
 To determine depth, thickness, formation temperature and pressure of a
reservoir.
 To distinguish between oil, gas and water zones in a reservoir.
 To measure hydrocarbon mobility.
WELL LOGGING

18. A LOG TYPES
 Lithological Logs
 Spontaneous Potential (SP)
 Gamma Ray (GR)
 Porosity Logs
 Neutron
 Density
 Sonic
 Resistivity Logs (Fluid Type)
 Resistivity
 Induction
 Other
 Dip meter
 Caliper
 Temperature
 Acoustic
 Formation micro imager (FMI).

19. Interpretation of well log section

20. SEISMIC INTERPRETATION

21. CONCLUSION
 The main part of work is on interpretation of seismic and well log.
 The collection of data enabled to read the depth of log borehole, types of lithology by the
principles of gamma, neutron, density, etc., these are the tools which applied to read the
subsurface lithological data.
 The calculations of well log interpretation reveals that as the water percentage decreases
the hydrocarbon percentage increases the vice versa also is true.
 In overall conclusion of this particular dissertation work helped us to read well log
sections and also seismic section or how to interpret.
 This is an important piece of work it was unable to have an exposure for final
semester geology students to complete the course. For students it’s a great
opportunity to work in ONGC helped in great way to learn some of the
basics in seismic interpretation and well log.

22. REFERENCES
 Edwin S. Robinson and Cahit Coruh, (1995), Basic exploration Geophysics by Virginia
Polytechnic Institute and State University. Pages- 502, 531-536.
 Robertson, (1989), Text book of Krishna-Godavari Basin. Stratigraphy, Petroleum Geochemistry
and Petroleum Geology, Volume-I Part-A.
 R.E.Chapman, (1978) Petroleum Geology, pages-1 to 21.
 G. Narayana Rao, Sedimentation and Sub-surface Stratigraphy of KG-basin by Pages-27-44,
96-100.
 M.B.Ramachanra Rao, formerly chief geophysicist, GSI, Outlines of geophysical prospecting- A
manual for geologist, Pages 217-228.
 R. E. Chapman, Petroleum Geology pages-1 to 21, Published by Elsevier Science
publishing.com.inc, pages-1 to 21.
 Robertson, Text book of Krishna-Godavari Basin. Stratigraphy, Petroleum Geochemistry and
Petroleum Geology, Volume-I Part-A, Page76-105.
 R.Vaidayanadhan and M.Ramakrishnan, 2008, Geology of India volume 2 published by the
Geological Society of India, Pages 911-916.
 R. L. Sengbush (President Pexcon International Inc.), Seismic Exploration Methods, Published
by-IHRDC, Publishers, 137 Newbery Street, Boston and MA02116, Pages-1 to 29.
 Seismic Exploration Methods by R.L. Sengbush (President Pexcon International Inc.) pages-1 to
29.
 Published by-IHRDC, Publishers, 137 Newbery Street, Boston, and MA02116.
 Published by- Elsevier Science publishing.com.inc.
 Published by John Wiley and Sons, Inc, USA, 1988.
 Sedimentation and Sub-surface Stratigraphy of KG-basin by G. Narayana Rao, Pages-27-44,
96-100,
 Well Logging ( in non-technical language) 2nd edition by David E. Johnson and Katheryne E. pile,
pages 1-4, published by Penn well publishing company,2002.

23. Thank you