Petroleum Exploration and Hydrocarbon Traps

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Questions and Answers

What do sensitive gravity meters measure during oil exploration?

Infrared and ultraviolet light

Vibrations in the Earth's crust

Changes in the Earth's magnetic field

Tiny changes in the Earth's gravitational field (correct)

What is the purpose of sending down sound waves in offshore seismology?

To measure the speed of sound waves

To let them reflect and pick up the reflection with sensors (correct)

To create shock waves

To create a 3D image of the subsurface

What type of data is used to create seismic lines?

Magnetometer data

Gravity meter data

Geophone data (correct)

Satellite image data

What is used to create shock waves in onshore seismology?

Thumper truck Signup and view all the answers

What is measured by magnetometers during oil exploration?

Tiny changes in the Earth's magnetic field Signup and view all the answers

What is the purpose of seismic lines in oil exploration?

To interpret the structure, density, and shapes of rocks Signup and view all the answers

What is used to record seismic data during onshore seismology?

Geophones Signup and view all the answers

What is the result of interpreting seismic data?

A set of seismic lines Signup and view all the answers

What is the purpose of injecting gases such as NG, N2, LPG, or CO2 in oil extraction?

To increase the pressure within the reservoir Signup and view all the answers

What is the main purpose of chemical injection in oil extraction?

To increase the effectiveness of water injection Signup and view all the answers

What is the maximum water depth that a jack-up rig platform can operate in?

400-550 feet Signup and view all the answers

What is the main characteristic of a fixed platform?

It is anchored directly onto the seabed Signup and view all the answers

What is the main purpose of a semi-submersible platform?

To move from place to place Signup and view all the answers

What is the main characteristic of a tension leg platform (TLP)?

It eliminates most vertical movement of the structure Signup and view all the answers

What is the main characteristic of a spar platform?

It is similar to a TLP Signup and view all the answers

What is the maximum water depth that a semi-submersible platform can operate in?

10,000 feet Signup and view all the answers

What is the purpose of an overlying seal rock or impermeable rock in an oil reservoir?

To prevent the oil and gas from escaping Signup and view all the answers

What is the description of a rock with a porosity value of 15-20%?

Good Signup and view all the answers

What is the purpose of a porosimeter?

To measure the porosity of a rock Signup and view all the answers

What is the difference between a gas reservoir and an oil reservoir in terms of porosity?

A gas reservoir requires less porosity than an oil reservoir Signup and view all the answers

What is the relationship between porosity and permeability?

Higher porosity, higher permeability Signup and view all the answers

What is the purpose of a permeameter?

To measure the permeability of a rock Signup and view all the answers

What type of trap is formed when reservoir rock is split along a fault line?

Fault trap Signup and view all the answers

What is the study of the origin, composition, and distribution of rock layers called?

Stratigraphic trapping Signup and view all the answers

Study Notes

Hydrocarbon Traps

Hydrocarbon traps result from changes in rock type or pinch-outs, unconformities, or other sedimentary features.

Oil and Gas Exploration

Geoscientists interpret subsurface structure or configuration through gravity, seismic, and other methods.
Geophysicists study the subsurface structure.
Geologists understand the rocks.
Geochemists understand the subsurface fluids (petroleum).

Locating Oil

Sensitive gravity meters measure tiny changes in the Earth's gravitational field that could indicate flowing oil.
Sensitive magnetometers measure tiny changes in the Earth's magnetic field caused by flowing oil.
Satellite images record infrared and ultraviolet light.
Seismology involves creating shock waves that pass through hidden rock layers and interpreting the waves that are reflected back to the surface.
Computer processes the geophones data, then converts to Seismic lines/Seismograph.

Seismology

Onshore, a 'Thumper' truck creates shock waves, and sensors (formerly called stingers) are placed along the ground to record the reflected waves.
Offshore, sound waves are sent down, and the reflections are picked up with sensors (hydrophones or seismographs).
The speed of the reflected wave changes depending on the make-up of the rock type.

Porosity and Permeability

Porosity values for an oil reservoir:
- 0-5%: Insignificant
- 5-10%: Poor
- 10-15%: Fair
- 15-20%: Good
- 20-25%: Excellent
Porosimeter measures porosity.
Permeability values for an oil reservoir:
- 1-10 md: Poor
- 10-100 md: Good
- 100-1000 md: Excellent
Permeameter measures permeability.
Higher porosity, greater permeability.

Oil and Gas Traps

Conventional sedimentary rock: sandstones, limestones, and dolostones.
Structural trap: formed by deformation processes, such as anticline, fault, and salt dome traps.
Stratigraphic trap: formed by the study of the origin, composition, and distribution of rock layers.

Enhanced Oil Recovery

Miscible techniques: injection of gas, raising pressure, and expansion in the reservoir.
Chemical injection: involves "polymers" to increase the effectiveness of water injection.

Drilling for Oil and Gas

Deep water platforms: Jack-up rig, Fixed, Semi-submersible, Tension Leg Platform (TLP), and Spar Platform.
Each platform type has its own characteristics, such as water depth range, design, and functionality.

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Description

Learn about the methods and techniques used in oil and gas exploration, including the formation of hydrocarbon traps and the role of geoscientists, geophysicists, and geochemists.