In order to transport the extracted oil from the well to the central gathering place, field pipelines are needed. They are also designed to move "black gold" to other objects within the framework of the fishery. Depending on the pressure, field pipelines can be divided into three types: with high pressure, with medium and low. They can also be simple when there are no branches, and complex with branches. The method of laying field pipelines also subdivides them into underwater, aboveground, aboveground and underground.
Destination dependent
Field pipelines can be pressureless and pressure head. This division does not end there. For example, pipelines are flow-through when oil is pumped to the unit from the well by measurement: the diameter of the pipe, depending on the productivity of a given well, is 75-150 millimeters. Field technological pipelines are also needed. Prefabricated collectors are designed to transport oil to a unit where oil is prepared: gas, mineral salts, water are removed from it. The diameter of such collectors is 100-350 millimeters.
Field gas pipelines collect gas, field inhibitor pipelines supply reagents to wells, field pipelines supply water to support the formation. And for all this, pipes are needed. Installation conditions (for example, terrain) suggest when designing field pipelines which type is best used in this particular case. In gravity-flowing oil, gravity flows by gravity; in gravity-flowing oil, only oil can be pumped; free-flow ones distill oil separately, gas separately. But there are also combined types.
In addition, field pipelines, depending on the installation conditions (for example, on the presence / absence of slopes of the relief) are divided into the following types: - gravity (movement occurs under the influence of gravitational forces); - gravity-flow (only oil is pumped through the pipeline); - freely - self-propelled / non-pressure (oil and gas move separately from each other); - combined. During the construction of field pipelines, all this is necessarily taken into account.
If the oil is heated, it becomes more viscous, then the speed of its movement along the pipe increases significantly. This is used when pumping large quantities of oil. The difference between main and field pipelines is that the latter deliver minerals no further than the processing enterprise, this is its final point. And trunk - around the world. Nevertheless, the construction of field pipelines is indispensable; this is the most important component for the collection of oil and its commodity preparation, for the supply of water and gas for the RPM system.
It is oilfield pipelines built for technical needs and according to technological rules that transport produced products from the wellhead to the main trunk facilities of gas and oil pipelines or to the gas processing plant (oil refinery). Pipeline constructions are also needed to supply water simultaneously produced - from TsPPN and UPSV to KNS, and then from there to the field - its injection wells. Oil and gas production is characterized by the use of fairly sophisticated technologies; many research institutes are closely working on the development of pipelines and related mechanisms.
Operation of field pipelines
In order to increase the throughput capacity of prefabricated reservoirs when new wells are connected or productivity on the previous ones increases, it is necessary, as already mentioned, to reduce the viscosity and heat the oil. There are other ways: then waterlogged oil is introduced, a parallel oil reservoir (looping) is laid, or an additional pump is connected in parallel.
The main and production pipelines that transport marketable oil (when the saturated vapor pressure is not higher than 500 millimeters of mercury (66.7 kPa) at +38 degrees are usually called oil pipelines. And if products from oil wells are transported together with gas that is dissolved or It is in a free state, and the saturation pressure of oil vapor is absolute at +20 degrees, such pipelines are called oil and gas pipelines. If field water is transported, it is a water conduit.
The head value above 2.5 MPa happens in high-pressure pipelines, from 1.6 to 2.5 MPa - in medium-pressure ones, and less than 1.6 MPa - in low-pressure ones. In addition to terrestrial, underground, suspended and underwater, there are prefabricated or welded pipelines. The materials for them also differ: fiberglass, steel with a coating inside - anti-corrosion paint or polyethylene, as well as just steel. Corrosion of oil and gas field pipes increases if acid treatment of the well or hydraulic fracturing has been carried out. Associated water significantly reduces the pH in stagnation zones. Quite often, repair of field pipelines is required.
About metal corrosion
To reduce corrosion of steel pipes, manufacturers in recent decades have been conducting significant research and practical experiments. Thus, a whole complex of technical specifications was developed, where a number of the most important indicators are regulated, among which the corrosion rate. The production of corrosion-resistant pipes has begun, for which steel comes with the addition of chromium, titanium, and vanadium. Clad, multilayer, combined and many other types of pipes are designed for existing oil fields, for the construction of trunk and production pipelines.
Service life has increased, general corrosion has decreased. But the pipes have become much more expensive. At the same time, various organizations proposed for operation in the oil industry pipes made of plastic and fiberglass, as well as pure steel with a polyethylene coating, internal and external, with only an internal coating of varnishes and paints with anti-corrosion properties.
Set of rules
The Code of Practice (hereinafter referred to as the JV) “Production Pipelines” left the Technical Committee for Standardization (TC 465), was further approved by the Ministry of Construction of the Russian Federation in 2016 and came into force in June 2017. This document established the requirements for field steel pipelines, as well as they relate to the design, production and acceptance of work during the construction, reconstruction, overhaul of pipelines up to 1400 millimeters in diameter (inclusive). Overpressure should not exceed 32.0 MPa. JV “Field pipelines” should apply to all field steel pipelines, in particular:
1. For gas and gas condensate fields - gas pipelines-loops to the collection point or to the inlet crane, which is located on the field, that is, to installations for the preparation of sludge, panel-polymer anchoring devices or to buildings with switching valves.
2. For gas collectors - from well piping, untreated gas pipelines, unstable and stable gas condensate pipelines of any length.
3. For purified gas pipelines and inhibitor directly into the wells and other objects.
4. For pipelines for sewage with a pressure of more than 10 MPa, in order to feed them into the wells and pump them into the absorbing layers.
5. For inhibitor lines.
6. For methanol pipelines.
7. For oil fields and oil and gas - pipelines flowing from wells, except for sections on well clusters, to transport the product up to metering units.
8. SP 284 1325800 2016 “Field pipelines” also prescribes oil and gas pipelines for transporting well products from the metering unit to the oil separation point.
The document applies to all types of pipelines used in the oil and gas industry, and this list is very long. Field pipelines for oil and gas, which transport oil together with gas that is in a dissolved and free state, are assigned to oil and gas pipelines, and to pipelines - which supply degassed oil.
JV “Field pipelines” does not apply the rules to pipelines made of cast iron, composite and polymeric materials, as well as to main pipelines for transporting commercial-quality product and many other types. For example, other qualities must have pipes to transport products containing hydrogen sulfide, a product with a temperature above 100 degrees. These provisions are not affected by water conduits and process pipelines inside the site.
Departmental building codes (BCH)
The construction of main and field pipelines is controlled by BCH standards and applies to steel pipelines of 1,420 millimeters inclusive, according to these standards, reconstruction and construction of new equipment for existing and opening gas and oil fields is carried out. The area of ​​distribution is also controlled by design standards, including for underground storage facilities, where the overpressure of the medium (not more than 32 MPa). BCH “Main and field pipelines” also consider flow lines that are needed for transportation from the well, where the diameter and length are regulated depending on the technical calculations and flow rate of the wells (from 75 to 150 millimeters the diameter of the flow line and not more than four kilometers long).
Prefabricated collectors are designed to transport oil, which are laid from the metering unit to the pump station or the unit where the oil is prepared. The diameter of prefabricated collectors is 100 to 350 millimeters, the length may be more than ten kilometers. The VSN “Production Pipelines” sets the standards for inhibitor pipelines that supply chemical reagents to wells (not only to wells, but also other facilities where it is necessary in the framework of gas condensate, gas, oil and gas and oil fields. Water supplies are also required in the fields for construction and reconstruction of which is also necessary to rely on the Code of Regulations and Departmental building codes.
Water is supplied to injection wells in order to maintain pressure in the formation, after which formation water is extracted together with oil, collected and discharged into aquifers. The construction of trunk and field pipelines also provides for this important element. Water pipelines are divided into mains, starting the way from pumping stations on the second rise, to supply, which connect the main water supply to the pumping stations of each bush, to distributing, which connect the injection wells to the cluster pumping stations.
Gas and gas condensate fields
At such facilities, gas pipelines connect gas wells and gas treatment plants with gas distribution stations before gas enters the main gas pipeline, and gas condensate is collected and utilized with their help. They are divided into gas pipelines-loops, collector gas pipelines, condensate collection and field pipelines. All this is built and reconstructed strictly according to the rules that are presented in the BCH. A loop-gas pipeline connects the well to the separator, where all unnecessary impurities are separated from the gas itself, and gas is also dehydrated and prepared for transportation.
There are group installations and individual gas separation points. The length of the cables is from 600 meters to 5 kilometers, the diameter of the pipes is prescribed up to 200 millimeters. Gas manifolds for gas collection should connect group preparatory plants with gas distribution stations. The shape of the gas collection manifolds does not differ from other field gas pipelines that are used in oil fields. Condensate collectors are exactly the same as in oil fields collectors for collecting oil, they are used to transport gas condensate to a gas collection point or to a gasoline production plant.
Pipeline construction in Russia
Already in the eighties of the twentieth century in Russia everywhere they switched to the construction of pressurized pressure systems, vacuum gas pipelines are not being designed at new fields. Gas pipelines, similar to flow lines, are divided according to their purpose - into supply ones, first of all. Further similar to prefabricated oil manifolds are prefabricated gas manifolds, and, finally, injection pipelines.
The shape also depends on the configuration of the field, on the size of the deposits and on the placement of booster stations and metering plants. In oil fields, the gas collection system is named according to the shape of the reservoir: linear, if the collector is one line, radial, if the collectors are reduced to a single point, annular, if the reservoir surrounds the oil structure over the entire area with a ring. Usually, jumpers are designed in an annular collector for maneuverability and reliability.
Injection gas pipelines drive gas to the “cap” of the field from compressor stations in order to maintain reservoir pressure and extend the flow of wells, as well as to supply gas to the wellheads through gas distribution booths if the operating method is compressor. In the same way, gas is transported to refineries and gas fractionation plants for consumers.
Rules for the construction of field pipelines
Since these are capital engineering facilities, that is, designed for a long service life and are designed to transport oil products, gas and oil in an uninterrupted way from the production site to the comprehensive preparation facilities and the places of entry into the main pipeline (as well as any other type of transport, including river, sea ​​and rail), for the construction of many rules and regulations. The main thing is GOST 55990 (2014) “Field pipelines” for gas and oil and oil fields, which set out in section 8 design rules and rules for applying this standard. All changes are reported in the index "National Standards". Amendments and changes to the official text are published monthly and from the Internet by the Federal Agency for Technical Regulation and Metrology on the official website.
GOST "Field pipelines" applies to reconstructed and new steel pipelines with a diameter of 1400 millimeters inclusive, where the overpressure is not more than 32.0 MPa for oil, gas condensate and gas fields, as well as for underground storage facilities. The composition of field pipelines was discussed above; this is how the present standard works. These are gas condensate and gas fields for gas condensate and gas fields, gas collection manifolds, pipelines for stable and unstable gas condensate, for supplying inhibitor and purified gas to wells and other facilities requiring construction, sewage pipelines into wells (injection into absorbing layers), methanol pipelines .
GOST "Field pipelines" for gas and oil and oil fields is also described above. These are discharge pipelines, oil and gas gathering pipelines, gas pipelines for oil gas transport, oil pipelines for transporting gas-saturated or degassed anhydrous or irrigated oil, gas pipelines for the gas-lift method of oil production, gas pipelines for supplying to productive formations, pipelines for waterflooding, and also sewage and formation water disposal systems, oil pipelines for commercial transport of oil, gas pipelines for gas transport, inhibitor pipelines, demulsifier pipelines at gas and oil facilities births. GOST also provides pipelines for underground storage facilities - between the sites at the facilities.
Piping
Field and trunk pipelines cross a huge number of the most diverse natural and artificial barriers, which are called transitions - underwater, air or underground. Hydrogeological, natural, climatic conditions are also very different: rivers, ravines, gorges, karst-hazardous areas intersect. Sometimes only overhead laying is the only one possible. The construction conditions are diverse, and for each case, the norms and rules laid down in the GOST are provided. Each site must meet operational, production, economic requirements.
The failure of any link will stop working along the entire length of the pipeline, which is hundreds and hundreds of kilometers. . , . , , ( , - ).
- , , . , -. , . , - , , - - .
, : , , , , . - - , , . . - , . , , , , .
, , - . - , . , , , .
Internal corrosion of pipes is the most dangerous, it occurs because the products coming from the wells are stratified: oil at the top - separately, formation water at the bottom - separately. And the water is highly mineralized, there are a lot of various small particles that mechanically act on the lower part of the pipe, where grooves are formed along, peculiar grooves. It is because of them that a large part of the failure of the pipeline occurs. And such groove corrosion progresses very quickly: up to 2.7 millimeters per year.
Pipelines for the oil and gas industry are mostly seamless pipes, much stronger, since low-carbon steel is used only in the best grades and is well heat-treated. Oil pipes are made without thread, electric welding. Pipelines must have fencing, filling edge or other designation of the boundaries of the site. The pipeline route is determined by the size and direction of the technical corridor, that is, the group laying of pipes of different or identical purposes should be streamlined. This includes the linear part, and transitions through barriers of a natural or artificial plan, and shutoff nodes of valves, and devices for securing pipes, and devices for electrochemical protection against corrosion.
To ensure the operational reliability of the designed pipelines at each stage of their use - from commissioning and commissioning to dismantling and disposal, it is necessary to use the Code of Practice and not allow violation of the norms prescribed by GOST. In order to improve the quality at the design, construction and subsequent safe operation of field pipelines, these regulatory documents have been developed. First of all, it is necessary to minimize operational risks, to adequately manage them: to comply with all requirements of current technical regulations in accordance with standardization documents.