All language subtitles for ch2 p3

Number three fluid saturation.

Fluid saturation can vary due to the way

hydrocarbons displaced the seawater that was

present when the rock was formed.

We speak of this displacement in terms of saturation

percentages water percent oil percent or guess percent.

Let me explain.

Let's say that in your reservoir rock you have a

prosody of twenty five percent.

Within that twenty five percent you have a fluid.

If you took an actual measurement of some fluid from

the reservoir you might have a water saturation of

thirty percent and oil saturation of fifty percent

and against saturation of twenty percent.

This is all within your total fluid saturation.

Therefore we can write sw plus s or plus sg.

Equals thirty percent plus fifty percent plus

twenty percent equals one hundred percent.

These percentages are of great importance to the

reservoir engineer because they give a measure of

the economic value of the reservoir.

Formations with high s all and or high s g may indicate

a profitable reservoir.

And finally number for relative permeability.

When you mix oil water and gas in a reservoir rock they

remain in separate phases and will flow through the

reservoir channels at different rates.

For example if oil saturation is small the oil will

form discreet oil dropped to do.

It's surface tension.

And they will not be continuously connected to other

drops and so the oil will not flown.

The water molecules are continuous and will flow

freely bypassing the oil and thus producing only water.

Now if we have the reverse that is to say the fluid in

the reservoir is mostly oil then the oil phase is said

to be continues and it will flow bypassing the water.

The small amounts of water is bound to the sand grains

by capillary forces and is said to be immovable.

Thus this reservoir would produce one hundred

percent oil.

A general rule for many reservoirs is when s w is less

than twenty five percent.

Only oil will flow and when s o is less than twenty five

percent only water will flow and both oil and water

will flow when both sw and as or are greater than

twenty five percent.

The next section we're going to look at the migration

of petroleum.

Migration is that movement of oil from it's source

rocker world was created up in through the reservoir

rock and up and up until it gets trapped.

A trap is a hard type of rock that stops that flow oil

upward and at that point the oil starts to accumulate

and that's where the petroleum engineer and

exploration are looking for their life for traps

because that's where they find the accumulation of oil.

The place where oil is first formed is called the

source rock.

Usually a shale rock enriched with dead organic material.

Wants the oil is made in the source rock where does it go.

Petroleum must migrate and be trapped before it is

exploitable before we can economically get it out of

the graham.

All can migrate up vertically over geological time.

Oil will migrate upward until it stopped are trapped

by rock that is hard.

This hard rock or in permeable rock will not allow the

oil to migrate upwards further.

We call this or permeable rock a trap.

A trap must be made of impermeable rock.

It must be a bob then all around the oil.

It must keep the off from migrating.

There are three types of traps.

We're going to discuss structural.

Stratigraphic and combination of structural and stratigraphic.

Let's backtrack just a little.

Here is our source rock laid down as deposition at the

bottom of the ocean and it got little fide which

remove most of the water but of course some water

still remains.

The source rock contains the remains of the animals

and plants that died millions of years ago but it also

contains some water.

Now this source rock is usually buried very deep and

is under pressure with layer upon layer of newer

sediment that has been laid down during the years after.

This weight and pressure called overburden starts

to chemically change the remains of these plants and

animals and transform them into drops of hydrocarbon.

As these drops are formed they begin to move upward

out of the source rock into the water which moves it

further up.

This is called vertical migration.

Here is the reenactment you can see how drops of oil

form and then push up board caused by born to pressure

or density differences between oil and water.

Now getting back to our animation the oil migrates or

travels upward through permeable reservoir iraq

until it disappears into the surface.

Or it finds a reservoir rock with poor's prosody and

is trapped by an impermeable trap or camp rock.

These drops of hydrocarbon can travel over long

distances in geological time as it migrates always

upward or sideways horizontally through pours and

permeable reservoir rock.

So when we find reservoir rock full of hydrocarbons

it does not mean necessarily that the source rock is nearby.

The trap in this animation is an antique klein.

Here's another example.

All of this migration could have taken place

millions of years ago.

In this structure called and an incline we have three

fluids water oil and gas.

And if you remember from your chemistry oil gas and

water do not mix.

This is because of their densities are different.

If you look here where they separate you can see a line.

This is called the gas oil contact line or g o c.

And the oil water contact we call o w c.

These lines are important for the petroleum

engineer when he makes his analysis because they

will determine how well the oil will flow and also how

to prevent or reduce water from flowing into the well.

Another thing a trap must have is closure.

There must be a complete closure to make sure the oil

does not migrate around it.

Here is an example of a partial trap.

It looks like an an acclaimed but it has no closure.

The hydrocarbon drops can easily migrate out the

back and our lost.

The best traps are shaped like a ball that keeps the

hydrocarbons trapped inside.

There are three types of traps.

Here we will talk about the most common ones the

structural the stratigraphic and the combination

of structural and stratigraphic.

Structural traps are caused by defamation

something big like an earthquake or moving plates

have changed the rocks.

Stratigraphic traps are caused by irregularities

in the deposition of the layers when they were laid down.

Combination traps commonly known as angular on conformity.

Traps are composed of rock formations created from

both defamation and deposition.

In structural fault traps the formation of the rock

has changed.

You can see where the original reservoir iraq was bought.

The earthquake tilted the formation creating a trap.

Later oil and gas migrated into this space and was

trapped there.

Here is another type.

Let me tell you how it was formed.

First.

Salt is and evaporite that is formed when the ocean

water covering it dries up.

This expose salt in time then gets buried by other particles.

As it gets pushed down and squeezed this saw it

becomes hot and molten.

Sometimes this molten salt pushes up and breaks the

formation above it forming a salt dome.

It is structural because it pushed up and broke the formation.

Some of the broken rocks are reservoir rocks and the

of migration of oil will find these traps.

Salt is in permeable.

Whenever we find salt dongs we look for oil around

them because they are excellent traps for oil.