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Petroleum

Field

Operations

Dr. Sahar El-Marsafy

Professor

Chemical Engineering

Cairo University – Faculty of Engineering

Chemical Engineering Department

Fourth Year

1Chemical Engineering Department - Petroleum Refining Dr. Sahar El-Marsafy

11/16/2012

Chemical Engineering Department - Petroleum Refining Dr. Sahar El-Marsafy 2

11/16/2012

Flow Rate

Pre

ssu

re

What Happens When TPC and IPR Curves no

longer meet?

Pressure

differential

that must be

supplied by

artificial lift

Chemical Engineering Department - Petroleum Refining Dr. Sahar El-Marsafy

411/16/2012

Stimulation is used in order to improve the flow capacity of the reservoir

In many wells the natural energy can not produce a sufficient ∆P to cause the well to flow into the surface

Artificial lift is used to improve the flow capacity of the wellbore

Stimulation and Artificial Lift


5

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Required when reservoir pressure is no longer sufficient to lift fluids to surface due

production of heavier fluid column like water (water production)

reservoir depletion

decline in the production rate

Used to Increase the production from a free flowing well.

Artificial Lift…Why ?


6

11/16/2012

Natural

Flow

Conventional Methods

Secondary Recovery (20-30%)

Primary Recovery (10-15%)

Thermal Methods (Steam

Injection or In situ Combustion)

Artificial

Lift

Water

Flooding

Gas (NG or CO2)

Injection

Tertiary Recovery

Enhanced Oil Recovery (EOR)

Non-conventional Methods

Non-thermal

(Chemical) MethodsMicrobial Enhanced Oil

Recovery (MEOR)

Oil Recovery Phases


60 – 70%60 – 70%

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O&G Industry Stages


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Surface Petroleum

Operations

Wellhead


Wellhead

Wellhead

GOSP

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GOSP Flow Sheet


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Oil produced from wells moves through a

system of flow lines and trunk lines to gas

oil separation plant (GOSP).

Flow lines carry crude oil from individual

wells.

Trunk lines carry crude oil from several

individual wells. These lines are connected

to a manifold system just before the GOSP.


Gas/Oil Separation

(Process Description)

11/16/2012

Gas/Oil separation plant receives unprocessed crude oil directly from the oil wells. The GOSP provides the first stage separation of associated gas and water from the crude oil.

The operation of the GOSP is based on the following principles:

Under high pressure, gases will dissolve in the liquid. Crude oil is produced from the well head at very high pressure at which large volumes of gases are dissolved in crude oil. These gases will separate from the oil at reduced pressure.

Gas/Oil Separation

(Process Description)


11/16/2012

At high flow rates, oil will hold drops of water in suspension, if the wet crude flow is held or retained in a vessel, freely suspended water will separate from the oil and sink to the bottom.

The components of the GOSP operate according to these principles. The GOSP receives high pressure, wet crude which contains gas and salt water at high pressure and high flow rate. The processing vessels drop the pressure and flow rate of the crude stream and retain the crude for a short period. In these vessels, gas and water separate from the crude oil.

Gas/Oil Separation (cont.)


11/16/2012

Gas from the H.P. Separator goes to the knock

out drum.

Oil from the H.P. Separator goes to the LP

Separator.

Water from the H.P. Separator goes to the

water/oil Separator.

The H.P. separator is provided with a number of

control loops to regulate the level of oil, water

and pressure inside the vessel.

High Pressure Separator


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Production Header

It receives crude oil from the flow lines which come

from the individual wells, then flows to the H.P

separator.

Test Header

The flow lines are also connected to the test

header. Only one well at a time flows into the test

header, then it flows to the high pressure test

separator to test the crude oil from a single well.

Major Equipment of a GOSP


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High Pressure Separator

This vessel separates most of the associated gas

and water, its pressure is about 200 psig lower than

the production header pressure. The vessel

provides retention (holding) time to allow for the

freely suspended water and dissolved gas to

separate.


(cont.)


11/16/2012


(cont.)

Production separators are the major vessels in the

GOSP.

There are three types of Separators:

High Pressure Separators H.P

Intermediate Pressure Separators I.P

Low Pressure Separators L.P

The number of separators depends on the pressure of the oil incoming from the well head. If it is below 300 psig, then the GOSP will have only one separator, if it is more than 500 psig, then three separators will be available.


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Gas/Oil Separator


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This vessel receives oily water from the H.P. Separator & H.P.T. Separator and its function is to separate the oil that remains in oily water.

The WOSEP is a large vessel provided with baffles, the retention time is enough to separate oil from water.

Oil from WOSEP flows to the L.P. Separator and water flows out from the bottom.

Maintain pressure in the WOSEP at about 20 psig higher than the L.P. Separator عشان السائل يطلع للسيباريتور بدون بامب

A pressure control loop regulates the flow of gas in or out the vessel, when the pressure is low.

Water/Oil Separator


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The function of this separator is to test the percentage of gas, oil and water in the crude from individual wells. It is also used to sample the crude from a single well to test for impurities. The manifold system can direct flow from different flow lines into the test header then to the test separator.

This vessel is a three phase separator. It is similar in design and operation for to the H.P. separator. From the test vessel, flow will be as follows:

Gas flows to the K/O Drum.

Oil flows to the L.P. Separator.

Water flows to the water/oil separator.

H.P. Test Separator


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L.P. Separator

This vessel is maintained at about 50 psig, it

receives the oil from the H.P. Separator, H.P.T

Separator & K/O drum. Its function is to

separate further gas from oil.

The gas flows to the gathering centre, while the

oil flows to the storage tank or stabilization

system.


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The function of this drum is to separate drops of oil from

gas. The drum is provided with a demister at its top

made up of fine mesh pad that filters drops of oil out of

the gas.

It is also fitted with a deflector near the gas inlet, which

causes the gas to spin in its motion and loosens the oil

drops and makes them fall down.

Gas from the top is controlled by a pressure control

valve and flows to the gathering centre. Oil flows under

LC to the LP Separator.

Knock Out Drum


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Mechanical Devices

Why?

To obtain good separation

Speed down the separation process

Optimize the retention time


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Mechanical Devices


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Deflector Plate

Located in front of the inlet

Cause a rapid change in

direction & velocity of fluid

Forcing the liquids to fall to

the bottom of the vessel.

Responsible for the initial

gross separation of liquid

and gas.

Mechanical Devices


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Coalescing Plates

Arranged in an inverted V-shape

The liquid droplets in the gas hit

the plates and stick to them.

More droplets form bigger drops

that fall to the bottom

Mechanical Devices


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Mist Extractor

Composed of a mass of wire

netting

Located before the gas outlet

Fall down the tiny oil droplets in

the gas

Foam Breaker

Made of wire mesh, like mist

extractor

Prevents forming of foams (oil

and gas)

Mechanical Devices


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Weir Plate

Located at the bottom of the vessel

Divide the separator into two

compartments

Control the water level

Permits oil to overflow into the oil

compartment

Mechanical Devices


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Horizontal Cylinder

Vertical Cylinder

Spherical Vessel

Classification of Separators


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Horizontal Separators


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Advantages

Normally more efficient at handling large amounts of gas

Cheaper than Vertical separator

Large liquid surface area for foam dispersion generally

reduces turbulence

Disadvantages

Liquid level control is more critical

More difficult to clean produced sand, mud, wax, paraffin,

etc. (Why??)Bebo


Horizontal Separators

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Vertical Separators


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Advantages

Takes up less space than a horizontal separator with

the same capacity

More flexible than horizontal

Have good bottom and clean out facilities

Liquid level control is not so critical

Can handle more sand, mud, paraffin, wax without

plugging


Vertical Separators

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Disadvantages

Some of the instruments and safety devices

may be difficult to access without ladders or

access platforms

More expensive than horizontal separator

Require larger diameter for a given gas

capacity


Vertical Separators

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Spherical Separators


They are not widely used

They are difficult to fabricate

11/16/2012

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