1. INTRODUCTION TO
EXPLORATION & PRODUCTION
By: Vinay Varghese

2. HOW DO WE KNOW WHERE TO EXPLORE ?
• Exploration is a tricky business, it is a guessing game.
• Since there is a lot of investment once you fix a location to
explore, we do not leave everything to chance.
• We look for a petroleum system.
• So, what is a petroleum system ?
•A Petroleum System is a dynamic hydrocarbon system that
functions in a restricted geologic space and time scale.
•A Petroleum System requires timely convergence of
geologic events essential to the formation of petroleum
deposits.

3. WHAT ARE THE GEOLOGICAL EVENTS WE LOOK
FOR ?
•Mature source rock
•Hydrocarbon expulsion
•Hydrocarbon migration
•Hydrocarbon accumulation
•Hydrocarbon retention

4. Cross Section Of A Petroleum System
Overburden Rock
Seal Rock
Reservoir Rock
Source Rock
Underburden Rock
Basement Rock
Top Oil Window
Top Gas Window
Geographic Extent of Petroleum System
Petroleum Reservoir (O)
Fold-and-Thrust Belt
(arrows indicate relative fault motion)
Essential
Elements
of
Petroleum
System
(Foreland Basin Example)
(modified from Magoon and Dow, 1994)
O O
Sedimentary
BasinFill
O
Stratigraphic
Extent of
Petroleum
System
Pod of Active
Source Rock
Extent of Prospect/Field
Extent of Play

5. • The following are basic principles or laws are used to evaluate the
relative ages and the relations among rock layers.
• Uniformitarianism - “The present is the key to the past.” By studying
modern geologic processes, we can interpret past geologic events
and rock-forming processes.
• Original Horizonality - “Sedimentary layers are deposited in a
horizontal or nearly horizontal position.” If sedimentary layers are
tilted or folded, they have been subjected to deforming stresses.
• Superposition - “Younger sedimentary beds occur on top of older
beds, unless they have been overturned or faulted.”
• Cross-Cutting Relations - “Any geologic feature that cuts another
geologic feature is younger than the feature that it cuts.”
Basic Geologic Principles

6. FORMATION OF PETROLEUM

7. ROCKS
• Before we proceed to understand where oil is formed we must
familiarize ourselves with a few terminologies of rocks.
• The three major rock types are sedimentary, igneous, and
metamorphic rocks. Their classification is based on their origins.
• Sedimentary rocks are formed from particles derived from igneous,
metamorphic or other sedimentary rocks by weathering and
erosion. Sedimentary rocks provide the hydrocarbon source rocks
and most of the oil and gas reservoir rocks.
• Igneous rocks are formed from molten material which is either
ejected from the earth during volcanic activity (e.g., lava flows, and
ash falls), or which crystallizes from a magma that is injected into
existing rock and cools slowly.
• Metamorphic rocks are formed by subjecting any of the three rock
types to high temperatures and pressures, that alter the character
of the existing rock. Common examples of metamorphic rocks are
marble derived from limestone.

8. The Rock Cycle
Magma
Metamorphic
Rock
Sedimentary
Rock
Igneous
Rock
Sediment
Heat and Pressure
Weathering,
Transportation
and Deposition
a
n
i

9. • Petroleum is not found in a large pool or a whole
accumulation of liquid like an underground storage tank.
• It id found in the pore spaces of the rock.
• What is porosity ?

11. RESERVOIR TRAPS
• When we look for a water reservoir on land, we look for
depressions because water will move downhill naturally and
accumulate in a bowl shaped formation.
• For oil, it is not the same. We all know one thing that oil floats
on top of water, because it has a density lighter than that of
water.
• So naturally it will not settle in depressions but will
accumulate on troughs or under dome like structures.
• For this to occur we need an impermeable or low
permeability layer of rock over the rock in which the
petroleum has accumulated.

12. GEOLOGICAL STRUCTURE BECOME THE TRAPS
• As we saw earlier, that petroleum is formed mainly in
sedimentary rocks. Sedimentation occurs layer over layer,
mostly in a horizontal manner or near to horizontal manner.
• This horizontal sedimentary rock is disturbed by continuous
tectonic activity, which causes the rocks to fold, break, slide
along the path of least resistance, crack. Basically it damages
the structure which took millions of years to form.
• This damage when leads to an impermeable layer against a
reservoir, trapping the petroleum, when it forms fold for
accumulation of petroleum is a boon to us.

13. SURVEY
• We can conduct a survey of the chosen field, by various
methods.
1. Gravity: The density of basement rocks is always higher to that of
sedimentary rocks and so the gravitational pull due to the high
density basement is more. So from this we get a profile of the
basement rocks.
2. Magnetic: The magnetic field of the basement rock creates
anomalies in the earths gravitational field, so if the basement rock is
closer the distortion will be higher and vice versa.
3. Seismic: Every rock has an intrinsic property of allowing a certain
amount of sound waves to pass through and it reflects the rest.
Using this property of the different rocks, we can determine which
rock is at what depth depending on the reflectivity of that layer.
Giving us a picture of the sub surface.

14. DRILLING
•Drilling an oil well is in many
ways similar to drilling a hole
into the wall, only the desired
level of safety and precaution is
much higher because we do not
know what we are going to face
in the subsurface.
•We do go in with a fair idea,
but it is never full proof. We are
dealing with high pressure
fluids, at high temperatures,
which if left unmonitored will
surely lead to a disaster.

15. WHAT DO WE NEED TO DRILL ?
• Drill bit: This is the most useful equipment on the rig, because
this is what will crush the rock and allow us to move deeper
into the earth.
• Drilling mud: As the drill bit faces higher temperatures and
harder rocks, its temperature will keep on increasing, which is
not good for the life of the bit, so we introduce drilling mud
which lubricates, cools and helps bringing the cut/grinded
material back to surface.

18. BLOWOUT PREVENTOR
• From the discussion above we know that drilling a well is not
such an easy task because of the pressure and flammable
fluids that we may encounter in the sub surface.
• To avoid the sub surface fluids to reach the surface in case of
entering an unexpected interval of hydrocarbon fluid, we use
an equipment what is known as a Blowout Preventor (BOP).
• BOP is a stack of RAMS that cut the annulus region from the
surface in case of a blowout.
• There are three type of RAMS:
1. Annular RAM
2. Pipe RAM
3. Blind RAM

22. ENHANCED OIL RECOVERY
• Enhanced oil recovery deals with maintaining the pressure of
the pressure of the reservoir by injecting water or gas,
polymers to push the liquid further towards the well.
• In situ combustion and steam injection for highly viscous
petroleum to heat it and allow the fluid to flow towards the
wellbore.