This document summarizes different types of surface indications of subsurface oil and gas accumulations. It describes active or live occurrences such as seepages, springs, and mud volcanoes. Seepages occur along fractures and joints in rocks, allowing petroleum to reach the surface. Mud volcanoes form when high pressure gas and water carries mud, sand, and rock fragments to the surface. The document also discusses fossil or dead occurrences, including disseminated occurrences where oil is distributed throughout pore spaces, and vein or dyke deposits where bitumen fills rocks.

1. PRESENTED BY:

2. TOPIC:
 Surface Indication of subsurface oil and
gas accumulation

3. TABLE OF CONTENT:
 Active or Live occurrences
 Seepages, Springs
 Mud volcanoes, mud flows
o Miscellaneous occurrences
o Fossil or Dead occurrences
 Disseminated occurrence
1. Inspissated Deposits
2. Primary mixture of rock and bitumen
 Vein or dyke like deposits filling rocks and fissures

4. Surface Indication Of Subsurface
Oil And Gas Accumulations-
1. Active Or Live Occurrences
 a)Seepages, Springs, etc
 b)Mud Volcanoes, Mud Flows
2. Miscellaneous Occurrences
3. Fossil Or Dead Occurrences
 a) Disseminated Occurrences
 i) Inspissated Deposits
 ii) Primary Deposition Of Rock And Bitumen
 b) Vein Or Dyke Like Deposits Filling Rocks
And Fissures

5. petroleum that exudes in the form of springs and seepages may
reach the surface along fractures, joints through any of the
connected porous opening of the rock. Petroleum seepages are
common in the sedimentary regions of the world and many pools
have been discovered by drilling near seepages. Surface seepages
associated with water springs. Gas seepages are readily observed
when they occur it bubble through water.

6. SEEPAGES
:
the slow escape of a liquid
or gas through porous
material or small holes.
seepages

7. Thrust fault
seepages
seepages
Fault

8. Seepages overlie a faulted
anticline

9. MUD VOLCANOES:
 High pressure gas water seepages carries mud, sand, fragments of rock and oil with them.
 Generally comes up through fractures & fissures or squeezed out through plains & fault.
 Mud eruption depends upon three factors:
 i) local pressure
 ii) available amount of gas, water & mud
 iii) size & shape of openings
 Mud volcanoes may range in size from merely 1 or 2 meters high and 1 or 2 meters wide, to 700
meters high and 10 kilometres wide.
 The largest mud volcano is “LUSI” in Java, Indonesia which is 10Km in diameter.

10. Miscellaneous
Occurrences:
Found in fossil cast, in
cavities, etc.
Only few fossil cast
present contains
bitumen.

11. 1.DESSEMINATED
OCCURENCES:-
 Sediment containing thick and
heavy oil are disseminated
throughout the pore spaces of the
rock either as bonding material or
matrix
FOSSIL OR DEAD
OCCURENCES
(a).Inspissated deposit:- once a pool
in liquid and gaseous form and now
consist of only the more resistant and
heavier residue.
(b).Primary mixtures of rock and
bitumen:-the whole mixtures have
been buried by younger sediment and
then exposed by erosion

12. VEIN OR DYKE LIKE FILLING/DEPOSITS
 The group of related bitumens are occur as
vein filling or dyke.

13. THANK
YOU
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