Reservoir engineering - Middle East Technical University

“RESERVOIR ENGINEERING”



MIDDLE EAST TECHNICAL UNIVERSITY



Spring

2008

Department

of Petroleum and Natural Gas Engineering

Dr. Mahmut Parlaktuna

Res. Assist. Sevtaç Bülbül



A
r
eservoir

is
formed

of
one

(
or

more
)
subsurface

rock

formations
,
containing

liquid

and
/
or

gaseous

hydrocarbons
, of
sedimentary

origin
.




The

reservoir

rock

is
porous
and

permeable

and

bounded

by

impermeable

barriers
,
which

trap

hydrocarbons
.

RESERVOIR ENGINEERING

A cross
-
section of a typical
hydrocarbon reservoir

(
R.
Cosse
, Basics of R
eservoir

E
ngineering
, 1993
)


R
eservoir

engineering

is
concerned

with
:


–
produc
ing

oil and gas
reservoirs in such a way that
the
economic

recovery is
maximized
,
and

–
the rate at which the
petroleum is produced is
maximized.

RESERVOIR ENGINEERING



Reservoir engineer

deals with:


–
Control of amount of gas

&

water produced with oil


–
Proper placement of wells


–
Use of proper distance between wells


–
Injection of water or other fluids into the reservoir
and many other means are used to help to
maximize the oil.


RESERVOIR ENGINEERING



Image

of
the

reservoir
:
forms
,
boundaries
,
distribution

and

volumes

of
fluids


Well

characteristics
:
e.
g.average

permeability


Recovery

mechanisms
:
natural

drive
,
enhanced

oil

recovery


Reservoir

Simulation
:
Integrating

the

reservoir

data
and

flow

laws


computer
models to predict the flow of
fluids


RESERVOIR ENGINEERING


(R.
Cosse
,
Basics

of R
eservoir

E
ngineering
, 1993)

Reservoir Simulation

(R.
Cosse
,
Basics

of R
eservoir

E
ngineering
, 1993)


After a well has used up the reservoir's
natural
drives
and gas lift or pumps have recovered all the
hydrocarbons possible, statistics show that 25 to
95% of the original oil in the reservoir may still be
there.




This amount of oil can be worth recovering if
prices are high enough.




Enhanced Oil Recovery (EOR)

Enhanced Oil Recovery
;

–
is the recovery of oil from a reservoir using
means other than using the natural reservoir
pressure.

–
generally results in increased amounts of
produced

oil

–
Its purpose is not only to restore
formation

pressure
, but also to improve oil
displacement

or
fluid flow in the
reservoir
.



Enhanced Oil Recovery (EOR)


Secondary recovery
processes generally use
;

–
injection of water
or
natural gas
into the production
reservoir to replace or assist the natural reservoir
drive or primary production.





Enhanced Oil Recovery (EOR)


(www.bp.com)



Tertiary recovery
methods
are

used

where
secondary recovery methods leave
-
off.
T
hree

major
categories;





Enhanced Oil Recovery (EOR)

(http://www.seed.slb.com/en/scictr/wa
tch/climate_change/capture.htm)

1)
Thermal displacement


(
steam

injection
,
in
-
situ

combustion

2)
Chemical displacement


(
polymer injection, polymer
flooding and caustic
flooding
)

3)
Miscible displacement

–
(
hydrocarbon displacement,
CO
2

injection and inert gas
(nitrogen) injection





Oil and gas are not usually salable as they come
from the wellhead.


Typically, a well stream is a high
-
velocity, turbulent,
constantly expanding mixture of hydrocarbon liquids
and gases mixed with

–
water and water vapor,

–
solids such as sand and shale sediments,

–
sometimes contaminants such as carbon dioxide and
hydrogen sulfide.



Several steps are necessary to get oil or gas ready
to transport to its next stop


Surface Handling of Well Fluids



The well stream is first passed through a series of
separating and treating devices
;


–
to remove the sediments and water

–

to separate the liquids from the gases,

–
to treat the emulsions for further removal of water, solids,
and undesirable contaminants.



The oil is then
stabilized
,
stored
, and
tested
for
purity. The gas is tested for hydrocarbon content
and impurities, and gas pressure is adjusted to
pipeline or other transport specifications.



Surface Handling of Well Fluids


Surface Handling of Well Fluids




At the wellhead,
separators

are used to separate the
remaining gas in solution by or adjusting pressure in the
separator.



Water

is separated due to the gravity difference.




Crude oil
is fed into crude oil line
.



G
as
is flowed through the gas line.


Crude oil
is stored in large
tanks

after produced.



N
atural

gas
;

–

is
liquified

before storage.
(
Liquefied natural gas
or LNG
)


–
It is also stored in
underground formations

(
depleted gas reservoirs
,
aquifers
, and
salt
caverns
)
.



Natural gas is injected into suitable formations when
demand is low. Then it is produced when demand is
high.


Storage



C
rude oil
taken from
oil

fields
is carried to refineries near the
big markets by
;

–

P
ipeline
s

or

–
Tanker
s

depending upon whether it is
being moved overland or by
water.

Railroad tank cars
and even
trucks

are sometimes used to
carry crude oil from the fields
that cannot be reached by
pipelines.


Transportation



Natural

Gas

is moved primarily by
pipeline
s.



The gas transport system is therefore mostly on
land, with collection systems, continent crossing
pipelines, and local distribution systems.



Liquefied natural gas (LNG)
and liquid gas products
such as propane are moved by
ship, barge, truck, rail and
pipeline
s.


Compressed

natural

gas

(CNG)

can be

transported

by

tank
trucks
.

Transportation



Crude oil is often a dark, sticky liquid that cannot be
used without changing it.



An
oil refinery
is an industrial
process

plant where
cruide

oil

is processed and refined into more useful
petroleum

products

such as
gasoline
,
diesel

fuel
,
asphalt

base
,
heating

oil

and
liquefied

petroleum

gas

(LPG).



Refining



The first part of refining
crude oil is to heat it until
it boils. The boiling liquid
is separated into different
liquids and gases in a
distillation column.

THANKS FOR LISTENING.