Petroleum is accumulated in reservoir rocks with properties like porosity and permeability. There are three types of rocks: source rocks where oil is generated, reservoir rocks where oil accumulates, and cap rocks that trap the oil. Oil migrates upward through reservoir rocks until it reaches cap rocks where it becomes trapped under pressure. Well depths have increased over time, with the deepest well over 12km deep off the coast of Sakhalin Island in Russia. Non-vertical and forked wells allow drilling in multiple directions from a single wellbore. Major oil accidents include a 1960 blowout in Iran that lost over 120,000 barrels per day for 100 days and the 2010 Deepwater Horizon spill in the Gulf of Mexico that spilled 5 million barrels

1. In the name of Allah

2. petroleum
engineering

3. Accumulate place
The oil is accumulated in the rocks
that called reservoirs.
The rock must have some properties
to become a reservoir such as
porosity, permeability,... .
We have three kind of rocks: source
rocks, reservoir rocks, cap rocks.

4. Migration
As I said the oil accumulated in rock like
water in a sponge. These stones are under
pressure upper stones weight and they have
to been compressed and fill their self
porosities but the fluids that exist there
prevent them then the fluids move up. This is
known as migration.
When the fluids arrive to cap rock they can’t
pass from the rock because of the rock
property and their pressure began to
increase.

5. Reservoir pressure
After migration the reservoir pressure be
stable and decrease during the
production.
This stable pressure sometimes become
more than 7000psi.
At Iran's reservoirs pressure is about
5000psi(normal pressure is 14.696 psi).
At the beginning of producing a well we
don’t use anything to pump the oil to the
surface.

6. Oil well
First well has been drilled was in 24th
January 1859 via colonel Edvin Lorentin
derrick in Pennsylvania America.
Some months after drilling derrick well in
27th august 1859 a new well with 230m
depth was drilled.
These two wells and the oil exploration
were the most important discovering in the
second half of 19th century.

7. Well depth
The deepest well of the word is in
Russian island “sakharin” with
7.7mile(12.39 km) depth that
7.1mile(11.42 km) of it is in offshore. they
use 4 power plant with 7500psi power.
This team is working on a project that
will drill the well until 9.3mile(15km) at
this island now.

8. Non-vertical & Forked well
In non-vertical wells(directional drilling)we
drive out the well from its vertical form and
sometimes become horizontal.
One of the new technology that uses in the
petroleum industry is forked well. In forked
wells at first we drill a well then with
directional drilling technology drill a new
well in another direction in well. this work
happens frequently in a well and we have
many wells in first well and new wells and
secondary wells.
The most forked well in the word has 30
branch.

9. Well blowing out
This means when the wells become incontrollable
for us that is called “wild well”. At this well the
reservoir fluid is blew out.
Two of the biggest blowing out (with comparing
the volume of the oil lost):
2-The second biggest blowing out happened in
20th April of 2010 in Mexican golf in Macando well
that was drilling with Horizon rig via British
petroleum company. In this incident about 53000
bbl/day of oil for three months and a total of five
million bbl. of crude oil was flowed into the Gulf
of Mexico.

10. Well blowing out
1-The biggest blowing out was
happened in 26th august 1956 in well
N.O. 5 in Alborz oil field in Qom. At
this incident it lost 120 thousand
bbl/day for a hundred days.
(in some citations 150 days)
the height of its fount was about
52m.

11. largest oil reserves
The biggest oil field is the Ghawar field in Saudi
Arabia with 75-83 billion bbl reserve.
the country with biggest oil reserve is Venezuela
with 297.6 billion bbl then Saudi Arabia (267.1
billion), Canada (173.1 billion), Iran (154.4 billion)
and Iraq (141.35 billion).