Oil resources extracted from a well in a field are not a raw material in its pure form. Prior to the stages of the production process of primary processing to obtain a trade object with the necessary consumer qualities, the future energy resource goes through several technological stages of processing. The need to implement these processes is due to the initial contamination of crude oil. Preparation for processing, in turn, provides not only a basic cleaning of the composition from impurities, but also a wide range of physicochemical operations with a point effect on individual characteristics of the mixture.
Preparation tasks
Different technologies for oil production from the field affect its final composition in different ways after extraction, which is especially expressed in the methods of fountain and elevator operation of the well. As a rule, the differences are expressed in the values of the undesirable components that are present in the liquid. In particular, the preparation of oil for primary processing aims to regulate the following indicators:
- Water. Water cut of oil can reach 98%, which requires a dehydration operation. Water itself, even in a refined petroleum product, can be used in certain proportions, however, even at the first stages of technological preparation, its presence complicates the study of the basic composition of raw materials, and also increases the cost of its transportation and maintenance.
- Associated gas. Again, the technology of the elevator production method has the greatest effect on the gasification of crude oil, since the energy of associated gas mixtures is used to raise the resource.
- Mineral salts. Oil is mainly characterized by the presence of chlorides. Alkali forms a film of hydrochloric acid during hydrolysis, which negatively affects the surface of the equipment serving the oil. Acceptable chloride content varies from 5 to 50 mg / l, depending on the processing process.
- Mechanical impurities. As a rule, these are suspended particles of sand, limestone and clay, and sometimes surface-active compounds that form unwanted emulsions.
Stages of oil preparation for refining
The organization of logistics in the preparation of crude oil for refining processes depends on the conditions of production in the field and the characteristics of its composition. In general, the phased process of this event can be represented as follows:
- The extracted oil goes to a special receiver on the surface of the well, where the first preparation processes, such as degassing, can be performed.
- Initial preparation at the field consists in the removal of produced water, coarse filtration, and the exclusion of the bulk of chlorides and solids.
- Raw materials are transported via the main gas pipeline to a special department of the oil refinery, where specialized preparation of oil for refining is carried out at the facilities of the same complex.
- Petroleum fluid enters the raw material park, where it is analyzed and the parameters of further preparation processes are determined.
- The basic preparation of raw materials on specialized equipment.
Oil gathering technology
Installations for the collection and transportation of oil under pressure are selected according to the characteristics of the flow rate of the well and the design capabilities for placing equipment with communication links. The complexity of this system is due to the fact that in order to optimize production, several collection points from different wells combined by one reservoir are simultaneously serviced.
What is the preparation of oil for refining at this stage? The resource enters the collection circuits in the form of a water-oil emulsion, which is separated by demulsifiers. Further, degassing processes are carried out with dehydration, but only to a degree sufficient to rationalize the transportation process. The pumping and delivery of oil itself is ensured by pumping stations located both at the resource extraction nodes at the fields and on the line of the pipeline leading to the refinery.
Complete equipment for oil treatment
To carry out the basic processes for preparing crude oil for further processing, ELOU units (electric desalting plant) are used. The processes of heat treatment, desalination, dehydration, purification from impurities, etc. are carried out on their platform. On modern ELOU devices, the process of preparing oil for refining is carried out with heat treatment up to 120 ° C, which is performed by steam heaters. Also, in some modifications, the presence of blocks with sumps that improve the quality of the output product is provided.
Preparation process
The list of technological stages of preparation may vary depending on the requirements for the processed raw material and its initial state. After pumping oil through a series of heat exchangers with heating, an electric dehydrator enters the work. At this stage, the main separation processes are performed, after which demulsifiers are introduced into the composition.
By the way, the preparation of oil for refining may also have reverse processes. For example, in an injector mixer, the operations of mixing oil with salt and water are performed. What is it for? Depending on the parameters of future processing procedures, the same salt (or alkali) may be required as a necessary component of marketable oil. The same applies to the water content. In addition, the salt is additionally introduced in order to neutralize acids and suppress possible processes of hydrogen sulfide corrosion.
Chemical method of dehydration and desalination
The regulation of the mineral composition of oil, coupled with the operations of dehydration and desalination, can be performed in various ways, including chemical. In this case, the working installation involves the introduction of demulsifiers into the emulsion. This is a group of chemicals, the addition of which ensures the separation of oil and water. Then a mechanical effect is made on the active molecules in a centrifuge with a separation effect.
Electrotechnical method of dehydration and desalination
This method of preparing oil for processing involves the use of the laws of physics, in which suspended particles under the action of current are naturally removed when the thermal regime and pressure in the emulsion containment chamber change. Thus, fractions of water, gas, oil and salt with impurities are separated.
Conclusion
Preparatory operations in the context of basic oil refining are expressed in a wide range of technological processes that use methods of chemical, physical, thermal and electromagnetic effects. Briefly, the preparation of oil for refining can be reflected in the form of the main operations of mechanical cleaning, desalination, dehydration and degassing. Moreover, each of these procedures will be conditional in nature, since there are no clear and universal parameters for the content of one or another component in the final product.
Water, alkali and even individual mechanical impurities can be a necessary component of marketable oil in certain ratios. In this sense, the tasks of preparing raw materials for production processing can be presented as a way to comprehensively regulate its characteristics with an emphasis on the requirements of a particular processing plant.