Where does it come from petroleum?

How the oil and gas? There are three main factors in the formation of oil or natural gas, namely: First, there is "original rock" (source rock) which allows the formation of geological oil and gas. Second, the displacement (migration) hydrocarbons from rocks into the origin of "reservoir rocks" (reservoir rock), usually sandstone or limestone porous (porous) and the size sufficient to accommodate these hydrocarbons.

Third, a trap (Entrapment) geological. Geological structure of the Earth's crust that does not irregular shape, due to the movement of the earth itself (such as earthquakes and volcanic eruptions) and erosion by water and wind continually, could create a "space" became an underground hydrocarbon traps. If the trap is surrounded by impermeable layers, the hydrocarbons were going to stay put and not move anywhere else.


Underground temperature, which is increasingly in the higher, is another important factor in the formation of hydrocarbons. Hydrocarbons rarely formed at temperatures less than 65 oC and generally loose at temperatures above 260 oC. Hydrocarbons are found mostly at moderate temperatures, from 107 to 177 oC.

What are the components of petroleum-forming?
Petroleum is a complex mixture of hundreds of hydrocarbon chains, which are generally composed of 85% carbon (C) and 15% hydrogen (H). In addition, there are also organic material and small amounts of oxygen (O), sulfur (S) or nitrogen (N).

Is there a difference from the types of oil?
Yes, there are 4 types classified according to age and location of its depth, namely: young, shallow, shallow, old, young and old-deep-deep. Young oil-shallow usually sour (sour), contains many aromatic ingredients, very thick and high sulfur content. Old oil-usually less viscous shallow, boiling point lower, and the paraffin chain is shorter.

Old-deep require the longest time for processing, the lowest boiling point and also the most liquid viscosity. Sulfur can teruraikan contained H2S can be loose, so the old-deep is crude to say the "sweet". Such oil is the most desirable because it can produce petrol (gasoline) the most.

How long does it take to form petroleum?
About 30-million years in the mid-Cretaceous period, at the end of the dinosaur era, more than 50% of world oil reserves are already known to form. Other reserves estimated even older. From a fossil is found along with oil from the Cambrian period, estimated age of about 544 to 505-million years ago.

The geologists generally agree that crude oil was formed over millions of years of organisms, plants and animals, are so small that lived in ancient seas. Once these marine organisms die, his body buried on the ocean floor and piled up sand and mud, forming a rich layer of organic matter that would eventually become sedimentary rock (sedimentary rock). This process continues over and over, single layer coating before closing. Then during the next millions of years, the oceans of the earth there is a shrink, or move.

Deposits that formed sedimentary rock generally does not contain enough oxygen to last mendekomposisi organic materials are complete. Bacteria break down this substance, molecule by molecule, a hydrogen-rich materials and carbon.

Pressure and higher temperatures than the rocks in the upper layer and then remains mendistilasi organic ingredients, then slowly turn it into oil and natural gas. The rocks containing the oldest known oil was more than 600-million years. The youngest was about 1-million years. In general, the rocks in which oil was found between the ages of 10-million and 270-million years.

How do I find oil?
There are a variety of ways: observation of geology, gravity surveys, magnetic surveys, seismic surveys, drilling test wells, or by educated guess and luck.
Gravity survey: This method measures the earth's gravitational field variations caused by differences in the density of the material in the Earth's crust geological structures.
Magnetic survey: This method measures the earth's magnetic field variations caused by differences in magnetic properties of rocks below the surface.
Both these surveys are usually conducted in a large area such as a basin (basin). From the results of this mapping, a new seismic method is generally performed.

Seismic survey using a shock wave (shock-wave) is directed to artificial through the rocks towards the target reservoir and the surrounding area. By various layers of material beneath the ground, these shock waves will be reflected to the surface and captured by the receivers as a means of pressure pulses (by the hydrophones in the water) or as an acceleration (by a geophone on the ground). The reflected signal is then digitally processed into a map of the surface acoustic to then be interpreted.

Application of seismic methods:
1. Stage of exploration: to determine the structure and Stratigraphy sediment where wells will be dug.
2. Appraisal and development stages: to estimate the volume of hydrocarbon reserves and to plan the best development.