This document provides an overview of gas hydrates, including their significance as an energy source, historical discoveries, identification methods, and exploitation techniques. It specifically examines gas hydrate occurrences in the Indian Exclusive Economic Zone, using the Krishna-Godavari Basin as a case study. Seismic data from the basin shows distinct bottom-simulating reflectors indicative of gas hydrates. While gas hydrates represent a potentially large energy resource, challenges to their safe and economic production include modeling their physical behavior, transporting the gas, and maintaining well stability during hydrate dissociation.

1. Gas Hydrates: Anomalous behavior of gas
hydrates in Indian Exclusive Economic Zones
with Advances in Exploration and
Exploitation Techniques – A Review
16th March, 2013.

2. Presentation Outlay
Significance
History
Occurrence
Identification methods
Case study
Exploitation techniques
Challenges/problems
Conclusion
References

3. Significance
+
STP
1m3
0.8m3
164m3

4. A REVIEW OF THE PAST

First observed in 1810 in the laboratory of Sir Humphrey Davy
as Chlorine hydrate.

In 1930s, Hammerscgmidt discovered hydrates as “pipeline
blockage”.

Later in 1970’s, Russian scientists made an allegation that gas
hydrates can be entrapped in water and can have large
reserves formed under natural environment.

Investigations were followed by the discovery of gas hydrates
in:


Siberian permafrost regions (Makogon et al. 1971)
Mackenzie Delta, Canada (Bily and Dick 1974)

5. Plausible Hydrate Formation Zones (jones et al., 2010)

6. Geophysical Proxies for Gas Hydrate
Pockmark
Wipeouts
Gas chimney
Seafloor collapse
Transparent zone
Amplitude reduction
Diapir
VAMPS
Mud volcano
Venting
Fluid flow along faults
(Wood et al., 2002)

7. LOGGING TOOLS
Logging tools most commonly used for refinement of
estimates :
Type of Log
Response to Hydrates







Mud Log
Increase of gas in Drilling mud
SP
Less negative compared to free gas
zone
Acoustic Transit Time Decreases relative to water or free
gas
Resistivity
Higher relative to free gas
Density
Very small decrease
Neutron Porosity
Nearly same as liquid water
Caliper
Oversized drill hole

8. QUANTIFICATION USING CORES

Two common ways of identifying
hydrates in cores:


IR imaging
Pressurized core sampling systems

A third method of sensing hydrates
is by use of chlorinity

A fourth rapidly evolving method:
CT scanning

Applies x-ray imaging techniques

9. Methane Hydrate Reserves in India
Gas hydrate stability thickness map (Sain et al, 2011).

10. CASE STUDY

11. KRISHNA GODAVARI BASIN
 Area of about 28,000 sq. km onshore and 145,000
sq. km extending in the offshore.
 National Geophysical Research Institute (NGRI)
acquired 2-D multi channel seismic (MCS) data
between 500 to 1500 m water depths.

12. Locations of seismic profiles (black lines) showing MCS data acquired
in KG basin. The identified BSRs have been marked white. Red and
green lines locate seismic sections that exhibit representative BSRs in
next Figure (Journal Geological Society of India, 2012).

13. Distinct BSR on specimen seismic sections along the (a) red and (b)
green lines, shown in above figure in KG basin. The CDP interval is 12.5
m (Journal Geological Society of India, 2012).

14. KRISHNA GODAVARI BASIN
 The predicted GHSZ thickness below the seafloor is
around 300m.
 The BSR being the primary proxy, other proxies that
have been identified in K-G basin:






Polarity reversal
Pockmarks
Gas chimneys
Crosscuts different lithological boundaries
Amplitude blanking
Pore water chemistry (To infer sulfate and chloride anomalies)

15. KRISHNA GODAVARI BASIN
 The gas hydrate occurrence in KG offshore is
associated with fractured clay.
 Microbiological studies (mainly enumeration of
sulfate and nitrate reducing bacteria and nitrifiers)
indicate the sediments are conducive for growth of
different bacteria.
 The good concentration of TOC in the cores adds
value to the suitability for Gas hydrate exploration.

16. EXPLOITATION TECHNIQUES
Gas hydrate production techniques for marine deposits (Collett et
al., 2009).

17. CHALLENGES/PROBLEMS
• Some of the common challenges/problems as
recorded in history are:
oAppropriate modeling of gas hydrates
response.
oPipeline construction for their transportation.
oHigh water and sand production.
oInstability of the surface hole during hydrate
dissociation.
oSlugging and Liquid loading.
oLack of proven conventional technology world
over.

18. CONCLUSION
 Large potential source of energy requires proper
identification.
 Understanding of the fluid behavior including phase
change, liquid accumulation, flow
regime, velocity, temperature, and pressure profile to
make that the proactive decisions regarding operation
and management of the system.
 Indian offshore has vast reserves of gas hydrates and
the need is of potential recovery with the implication
of the recovery methods.
 Suitability of the recovery methods depends on proper
understanding of the mechanism of their formation
and proper treatments.

19. REFERENCES
 Sloan, Koh (2008). Clathrate Hydrates of Natural




Gases, third edition. CRC Press.
Carroll, J. (2009). Natural Gas Hydrates A Guide for
Engineers, second edition. Elsevier.
Sanjeev Rajput*, M. K. (2009). Seismic indicators of
gas hydrates and associated free gas, SEG
International Exposition and Annual Meeting.
Houston .
Muhammad Iqrar Qadir, M. A. (Nov. 2011). Gas
Hydrates: A Fuel for Future but Wrapped in Drilling
Challenges, SPE 156516.
Kalachand sain, M. o. (June 2012). Gas-hydrates in
Krishna-Godavari and Mahanadi Basins. New
Data, journal geological society of india.

20. THANK
YOU