Mining is carried out using special engineering structures - drilling platforms. They provide the necessary conditions for development. The drilling platform can be equipped at different depths - it depends on how deep the oil and gas fields are.
Onshore drilling
Oil lies not only on land, but also in the continental plume, which is surrounded by water. That is why some installations are equipped with special elements, thanks to which they are kept on water. Such a drilling platform is a monolithic structure that acts as a support for the remaining elements. Installation of the structure is carried out in several stages:
- first, a test well is drilled, which is necessary to determine the location of the field; if there is a prospect of developing a specific zone, then further work is carried out;
- the site for the drilling rig is being prepared: for this, the surrounding area is maximally leveled;
- the foundation is poured, especially if the tower is heavy;
- on a prepared basis, the drill tower and its other elements are assembled.
Field Determination Methods
Drilling platforms are the main structures on the basis of which oil and gas are being developed both on land and on water. The construction of drilling platforms is carried out only after the presence of oil and gas in a particular region is determined. To do this, a well is drilled using various methods: rotary, rotary, turbine, volumetric, screw and many others.
The most common rotary method: when it is used inside the rock, a rotating bit is carried out. The popularity of this technology is explained by the ability of drilling to withstand significant loads for a long time.
Platform Loads
The drilling platform can be very different in design, but it should be built competently, primarily taking into account safety indicators. If not taken care of, the consequences can be serious. For example, due to incorrect calculations, the installation may simply collapse, which will lead not only to loss of finances, but also to death. All the loads that affect the installation are:
- Permanent: they mean forces acting throughout the life of the platform. This is the weight of the structures themselves above the installation, and water resistance, when it comes to offshore platforms.
- Temporary: such loads affect the structure under certain conditions. Only during the start-up of the installation is strong vibration observed.
In our country, different types of drilling platforms have been developed. To date, 8 stationary mining systems operate on the Russian plume.
Surface platforms
Oil can occur not only on land, but also under the water column. To mine it in such conditions, drilling platforms are used, which are put on floating structures. In this case, pontoons and self-propelled barges are used as swimming means - this depends on the specific features of oil development. Offshore drilling platforms have certain design features, so they can stay on the water. Different drilling rigs are used depending on how deep the oil or gas field is .
About 30% of the oil is extracted from offshore fields, therefore, more and more wells are being built on water. Most often this is done in shallow water by fixing piles and installing platforms, towers, necessary equipment on them. For drilling wells in deep water areas, floating platforms are used. In some cases, dry water drilling is performed, which is advisable for shallow openings up to 80 m.
Floating platform
Floating platforms are installed at a depth of 2-150 m and can be used in different conditions. Such structures can be compact in size and work in small rivers, and can be installed on the high seas. A floating drilling platform is a profitable structure, since even with small sizes it can pump out a large amount of oil or gas. And this makes it possible to save on transport costs. Such a platform spends several days at sea, then returns to base to empty the tanks.
Stationary platform
The stationary offshore drilling platform is a structure that consists of a top structure and a support base. It is fixed in the ground. The design features of such systems are different, so the following types of stationary installations are distinguished:
- gravitational: the stability of these structures is ensured by the dead weight of the structure and the weight of the received ballast;
- pile: they gain stability due to piles driven into the ground;
- mast: the stability of these structures is ensured by guy wires or the desired volume of buoyancy.
Depending on the depth at which oil and gas are being developed, all stationary platforms are divided into several types:
- deep-water columns: the base of such installations is in contact with the bottom of the water area, and columns are used as supports;
- shallow platforms on columns: they have the same structure as deep-sea systems;
- structural island: such a platform stands on a metal base;
- monopod is a shallow platform on one support, made in the form of a tower type and has vertical or inclined walls.
It is fixed platforms that account for the main production capacities, since they are more economically advantageous and easier to install and operate. In a simplified version, such installations have a steel frame base, which acts as a supporting structure. But the use of stationary platforms is necessary taking into account the static and water depth in the drilling area.
Installations in which the base is made of reinforced concrete are laid to the bottom. They do not need additional fasteners. Such systems are used in shallow deposits.
Drilling barge
Exploratory drilling at sea is carried out by means of mobile units of the following types: self-elevating, semi-submersible, drilling vessels and barges. Barges are used in shallow deposits, and there are several types of barges that can operate at very different depths: from 4 m to 5000 m.
A drilling platform in the form of a barge is used at the initial stages of field development when it is necessary to drill wells in shallow water or protected areas. Such installations are used at the mouths of rivers, lakes, swamps, canals at a depth of 2-5 m. Such barges are mostly non-self-propelled, therefore, they cannot be used for work on the high seas.
The drilling barge has three main components: an underwater submersible pontoon, which is installed at the bottom, a surface platform with a working deck and a structure that connects these two parts.
Self-lifting platform
Self-elevating drilling platforms are similar to drilling barges, but the first are more modernized and advanced. They rise on jack masts that rest on the bottom.
Structurally, such installations consist of 3-5 supports with shoes, which are lowered and pressed into the bottom for the duration of drilling operations. Such structures can be anchored, but the supports are a safer mode of operation, since the installation casing does not touch the surface of the water. Self-propelled floating platform can operate at a depth of up to 150 m.
This type of installation rises above the surface of the sea thanks to columns that rest on the ground. The upper deck of the pontoon is the place where the necessary technological equipment is mounted. All self-lifting systems are distinguished by the shape of the pontoon, the number of supporting columns, the shape of their cross-section and design features. In most cases, the pontoon has a triangular, rectangular shape. The number of columns is 3-4, but in early projects, systems were created on 8 columns. The rig itself is either located on the upper deck, or extends behind the stern.
Drilling ship
These drilling rigs are self-propelled and do not require towing to the site where work is carried out. The design of such systems is performed specifically for installation at shallow depths, so they are not stable. Drilling vessels are used in oil and gas exploration at a depth of 200-3000 m and deeper. A drilling rig is placed on such a vessel, and drilling is carried out directly through the technological hole in the deck itself.
At the same time, the vessel is equipped with all necessary equipment so that it can be controlled in all weather conditions. The anchor system allows you to ensure the proper level of stability on the water. After refining, the extracted oil is stored in special tanks in the hull, and then reloaded into cargo tankers.
Semi-submersible installation
Semi-submersible oil drilling platform is one of the popular offshore drilling rigs, as it can be operated at a depth of over 1,500 m. Floating structures can be submerged to a considerable depth. The installation is supplemented by vertical and inclined braces and columns, which ensure the stability of the entire structure.
The upper case of such systems is residential premises that are equipped with the latest technology and have the necessary reserves. The popularity of semi-submersible installations is explained by a variety of architectural solutions. They depend on the number of pontoons.
Semi-submersible plants have 3 types of draft: drilling, storm sedimentation mode and transition. The buoyancy of the system is provided by supports, which also allow the installation to maintain a vertical position. It should be noted that work on drilling platforms in Russia is highly paid, but for this you need to have not only the appropriate education, but also a lot of experience.
conclusions
Thus, the drilling platform is a modernized system of various types, which can drill wells at various depths. Designs are widely used in the oil and gas industry. Each installation has a specific task, so they differ in design features, functionality, volume of processing, and transportation of resources.