Crude oil extraction ( lec 3a )

Crude Oil Extraction

Crude Oil Extraction

Various steps in Extraction of Petroleum

are:-

Identification or locating of the Oil Field

Drilling

Oil Extraction and Recovery

• Primary Recovery

• Secondary Recovery

• Tertiary Recovery

Crude Oil Extraction

• Locating Oil fields

Before starting the extraction of crude oils, the crude oil fields has been identified.

There are number of methods available for this

1. Magnetometer

2. Gravimeter

3. Satellite imagery

4. Seismic surveys

5. Sniffers

Locating Oil fields

1. Magnetometer

An instrument used to measure the strength, direction of magnetic fields

Measure the change in earth’s magnetic field caused by oil flow

Locating Oil fields ( Cont. )

2. Gravimeter

An instrument used for measuring earth’s gravitational field

Typically designed to measure very tiny fractional changes in earth’s gravitational field

Tiny changes in gravitational field can give idea about oil flowing in earth

Locating Oil fields ( Cont. )

3. Satellite Imagery

Imagery is vital to exploration, geophysical surveying and in determining suitable drill sites based on surface conditions. A high-resolution image acquired prior to exploration and drilling activity serves as a baseline for other activities including site modeling, facilities monitoring, environmental assessments, and vegetation reclamation

4. Seismic surveys

creating shock waves that pass through hidden rock layers and interpreting the waves that are reflected back to the surfaceIn seismic surveys, a shock wave is created by the following:

• Compressed-air gun - shoots pulses of air into the water (for exploration over water)

• Thumper truck - slams heavy plates into the ground (for exploration over land)

• Explosives - detonated after being drilled into the ground (for exploration over land) or thrown overboard (for exploration over water)

Locating Oil fields ( Cont. )

Locating Oil fields ( Cont. )

4. Seismic surveys

Locating Oil fields ( Cont. )

5. Sniffers

They can detect the smell of hydrocarbons using sensitive electronic noses called sniffers.

High-tech devices that act like a "nose" are also used to detect traces of hydrocarbon gases that escape from below-surface oil deposits.

Drilling

• The oil well is created by drilling a hole into the earth

• A steel pipe (casing) is placed in the hole, to provide structural integrity to the newly drilled wellbore.

• Holes are then made in the base of the well to enable oil to pass into the bore

• Finally a collection of valves is fitted to the top, the valves regulating pressures and controlling flows.

Drilling Machine

Drilling

Primary Recovery

• During the primary recovery stage, reservoir drive comes from the natural mechanisms.

• Natural water displaces oil downward into the well.

• Recovery factor during the primary recovery stage is typically 5-15%

DrillingPrimary Recovery

Drilling

Secondary Recovery

• They rely on the supply of external energy into the reservoir in the form of injecting fluids to increase reservoir pressure, hence replacing or increasing the natural reservoir dry

• Other secondary recovery techniques increase the reservoir's pressure by water injection, natural gas reinjection and gas lift, which injects air, carbon dioxide or some other gas into the bottom of an active well, reducing the overall density of fluid in the wellbore with an artificial drive.

Drilling

Secondary Recovery

the recovery factor after primary and secondary oil recovery operations is between 35 and 45%.

Drilling (Secondary Recovery )

Drilling

Tertiary Recovery

• This type of method is used where oil is thicker and heavier than normal crude oil.

• Steam is injected into the oil reservoir to increase its mobility and thus reducing viscosity

• This method is also called Thermally Enhanced Oil Recovery method (TEOR).

Drilling (Tertiary Recovery )

• Some of the oil is burned to heat the surrounding oil

• In some cases, surfactants are added to alter the surface tension between oil and water

• Another method to reduce viscosity is carbon dioxide flooding

• Recovery rate is 5-15%

Tertiary Recovery

Recovery Rates

The amount of oil that is recoverable is determined by 3 major factors:

• Permeability of the Rocks

• The Strength of Natural Drives

• Viscosity of the Oil