Not infrequently a hollow layer of rocks that are not covered by a layer of hollow like mud, salt, or lime. It forms a sort of confinement for the hydrocarbons collected in one part of it. As the tectonic movement, was turned into a rock layer folds causing hydrocarbons come to adapt themselves. Hydrocarbons are trapped and then moving up to the bottom layer that is hollow, with the formation of gas at the very top, oil and water settle to the bottom layer.
The process of formation of the oil wells are still happening today. But the oil wells are still young (less than 60 million years) has not been saturated formation that is ready to be drilled. In some cases, erosion and strong support from the folds of the rocks lead to leaks of hydrocarbons out of their cages. Sometimes it moves towards the surface hydrocarbons and can be harvested without drilling, but the complex processing needed to separate sand and other impurities.
Seismic data and 3D visual modeling into the main guidelines in planning the drilling. After observations and surveys conducted on the soil layer, then the evaluation phase of the oil wells have been completed and the development phase can begin. At this stage it will be done which includes the drilling of development wells, installation of tubular, cementing, and production preparation. Series of special equipment used to drill oil wells is called rig. The main feature of the rig is made of steel towers used for raising and lowering the well tubular pipes so that the contents of the wells can be accessed.
The main components of the rig is the tower (derrick), the base platform (floor), drawworks, power source (drive), and medium silt (mud handing). To be able to access the wells, then a segment of pipe (drill string) installed every 30 meters. Put pressure on the pipe rotation and torque is obtained from a hydraulic or electrical stimulation is raised atop the tower. Components of the drill bit (cone) contained in the bottom of the well is used to dig the rocks. Types of rocks that will affect the excavated material and type of material used drill bits. All components are fully controlled by the drawworks. Precise calculation is needed, so drawwork not damage the pipe and drill bit at the bottom of the well.
Mud component serves to bring the rocks to the surface debris and cleanse and cool the drill bit at the bottom of the well. To avoid leakage of oil and gas, the mud should be able to give the equilibrium value of pressure at the bottom of the well. Oil and gas leaks can cause explosions situation (blow-out) and damage the rig equipment. Last prevention tool that is often used to prevent unwanted explosive situation is the safety valve is installed underground at the well pipe.
Usually the purpose dideviasi drilling vertically to the wells. In the modern drilling, wells accessible to 80o from the vertical axis is more easily penetrated septum formation and flow more oil. Drilling efficiency can also be done by creating a branch pipe for wells in different locations can be accessed by the same rig.
The shape and structure of the rig tends to vary according to type of operation and functions in the development stage. Rigs operating in the water (offshore rigs) are classified by the depth of the wells are accessible. The range of depths ranging from seven to thousands of meters in the sea. Drill rig on the ship the device placed on a ship and is controlled using a computer because its operation is very remote areas, far from land, and is used to access the wells on the sea. Rigs that have managed to access the well will be given a protective outer (casing) and the cement so that the layer formation along the well kept isolated and wellbore axial load can be maintained.