Or search for petroleum exploration is a long study involving several areas of study terrestrial and inexact science. For basic studies, research conducted by the geologists, that is, people who master the earth science. They are the ones responsible for the search of hydrocarbons.
Please note that the oil in the earth is not of a container that resembles a lake, However within the pores of rocks mixed with water. Illustration like the picture below
Geological Study
The science of geology, to determine an area has a potential in oil, then there are several conditions that must exist in the area. If one just does not exist then the area is not potential or even do not contain hydrocarbons. Conditions are:
- The source rocks (source rock). That is rock as raw material for the formation of hydrocarbons. usually acting as a source rock is shale. These rocks are rich in elemental content of carbon atoms (C) is obtained from the shell - the shell fossils in the rocks were deposited. Carbon is what will be a key element in the chain of constituent chemical bonds of hydrocarbons.
- Pressure and Temperature. To change these fossils into hydrocarbons, high pressure and temperature in need. Pressure and temperature will change the chemical bonds of carbon that is in-stone of the hydrocarbon chain.
- Migration. Hydrocarbons that has formed from the above process must be able to move to places where hydrocarbons have economic value to be produced. On the rocks source itself can be said is not possible for the hydrocarbon exploitation because there does not accumulate and can not flow. So this stage is very important to determine the possibility of exploitation of hydrocarbons.
- Reservoir. Is the rock which is a container for the hydrocarbons to gather from the migration process. This reservoir is usually a sandstone and carbonate rocks, because the two types of these stones have pores large enough for the storage of hydrocarbons. Reservoir is very important because on this rock in the production of petroleum.
- Trap. It is very important in a reservoir rock protected by traps. aim for hydrocarbons in the reservoir that accumulates in that place alone. If the trap is not there then somewhere else hydrocarbons can flow into the economy which means it will be reduced or totally uneconomical. Trap 2 is divided in the hydrocarbon trap structure and stratigraphic traps.
The study of geology is a regional study, if the regional is not possible to get hydrocarbons then there is no point to continue. If all the above criteria are met then the region is likely to have potential oil or natural gas. As for determining whether or not economically necessary that further studies relating to the physical properties of rocks. The research was continued in the next step.
Geophysical Studies
After a regional study using a method carried out geological, and the results indicate the potential for hydrocarbons, then the next stage is the stage to study geophysics. At this stage method - specific methods used to obtain more accurate data in order to ensure the presence of hydrocarbons and likely to be able to at exploitation. The data generated from the measurement of measurement is a reflection of the condition and properties of rocks in the earth. It's important to know whether these rocks have properties - properties as source rock, reservoir, and trap rock or rock that is not only important in terms of hydrocarbons. These methods use physical principles that are used as application engineering.
The methods are:
- Seismic Exploration. This is done before drilling exploration. areas of study are broad. of the study results will be obtained images of rock layers in the earth.
- Data Resistiviti. The basic principle is that any porous rock will be filled by the fluid. This fluid can be water, oil or gas. Distinguishing the fluid content within the rock one of them by using the existing properties on the fluid resistance. Fluid water has a low resistance value compared to oil, as well as oil resistance value is lower than the gas. of log data we can only distinguish low resistance and high resistance, not the kind of fluid because the fluid is different resitan value of each region. as a basis for analysis of fluid we need to take samples of the fluid in the rock area as our reference in the interpretation of the fluid from resistiviti data we have.
- Porosity data
- Data density. This data was taken using the logging tool with the aid of radioactive materials that emit gamma rays. Reflection of these rays will describe heavy rock types. Can we compare if the pore water with rocks containing heavy hydrocarbons will have different types