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RESERVOIR ENGINEERING
MIDDLE EAST TECHNICAL UNIVERSITY
Department of Petroleum and Natural Gas
Engineering
Dr. Mahmut Parlaktuna Res. Assist. Sevtaç Bülbül
Spring 2008
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RESERVOIR ENGINEERING

• A reservoir 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.

A cross-section of a typical hydrocarbon reservoir
(R. Cosse, Basics of Reservoir Engineering, 1993)
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RESERVOIR ENGINEERING

• Reservoir engineering is concerned with
• producing 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.

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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.

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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

(R. Cosse, Basics of Reservoir Engineering, 1993)
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Reservoir Simulation
(R. Cosse, Basics of Reservoir Engineering, 1993)
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Enhanced Oil Recovery (EOR)

• 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. 

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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.

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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.

(www.bp.com)
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Enhanced Oil Recovery (EOR)

• Tertiary recovery methods are used where
  secondary recovery methods leave-off. Three major
  categories

• 1) Thermal displacement
• (steam injection, in-situ combustion
• 2) Chemical displacement
• (polymer injection, polymer flooding and caustic
  flooding)
• 3) Miscible displacement
• (hydrocarbon displacement, CO2 injection and
  inert gas (nitrogen) injection

(http//www.seed.slb.com/en/scictr/watch/climate_c
hange/capture.htm)
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Surface Handling of Well Fluids

• 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

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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.

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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.
• Gas is flowed through the gas line.

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Storage

• Crude oil is stored in large tanks after
  produced.
• Natural 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.

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Transportation

• Crude oil taken from oil fields is carried to
  refineries near the big markets by
• Pipelines or
• Tankers
• 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.

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Transportation

• Natural Gas is moved primarily by pipelines.
• 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 pipelines.
• Compressed natural gas (CNG) can be transported
  by tank trucks.

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Refining

• 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).

• 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.

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