1. The scale must be clearly visible.
2. The approach to the pressure gauge must be free.
3. Depending on the installation height of the pressure gauge, the diameter of the device is selected:
· up to 2 meters - diameter 100mm;
· from 2 to 3 meters - diameter 160mm;
· over 3 meters - installation of a pressure gauge is prohibited.
4. Each pressure gauge must have a shut-off device (3x running valve, valve or tap)
Pressure gauge maintenance rules.
According to the technical instructions, land on "O"
Departmental inspection once every 6 months.
State verification - once every 12 months.
Remove and install pressure gauges only using a wrench.
In case of pressure pulsation, the following measures must be taken:
· when the pulsation is low, a compensator is welded in;
· for large pulsations, a special device is used - an expander with two chokes.
4. Providing first aid for loss of consciousness (fainting), heatstroke and sunstroke.
Ticket number 2
1. Parameters characterizing the productive formation.
Oil and gas accumulate in cracks, pores and voids in rocks. The pores of the formations are small, but there are many of them, and they occupy a volume that sometimes reaches 50% of the total volume of the rocks. Oil and gas are usually contained in sandstones, sands, limestones, conglomerates, which are good reservoirs and characterized by permeability, i.e. ability to pass fluids through itself. Clays also have high porosity, but they are not sufficiently permeable due to the fact that the pores and channels connecting them are very small, and the fluid contained in them is held motionless by capillary forces.
Porosity is the proportion of void space in the total volume of the rock.
Porosity depends mainly on the size and shape of the grains, the degree of their compaction and heterogeneity. In the ideal case (sorted spherical grains of uniform size), porosity does not depend on the size of the grains, but is determined by their relative position and can vary from 26 to 48%. The porosity of natural sand rock is, as a rule, significantly less than the porosity of fictitious soil, i.e. soil composed of spherical particles of the same size.
Sandstones and limestones have even lower porosity due to the presence of cementitious material. The greatest porosity in natural soil is inherent in sands and clays, and it increases (unlike fictitious soil) with a decrease in the size of rock grains, since in this case their shape becomes more and more irregular, and, consequently, the packing of grains becomes less dense. Below are porosity values (in %) for some rocks.
Shales 0.5–1.4
Clays 6–50
Sands 6–50
Sandstones 3.5–29
Limestones and dolomites 0.5–33
As depth increases due to increased pressure, the porosity of rocks usually decreases. The porosity of reservoirs for which production wells are drilled varies within the following limits (in%):
Sands 20–25
Sandstones 10–30
Carbonate rocks 10–20
Carbonate rocks are usually characterized by the presence of cracks of various sizes and are assessed by the fracturing coefficient.
One of the characteristics of rocks is their granulometric composition, on which other physical properties largely depend. This term refers to the quantitative content of grains of different sizes in the rock (in % for each fraction). The granulometric composition of cemented rocks is determined after their preliminary destruction. The granulometric composition of rocks to a certain extent characterizes their permeability, porosity, specific surface area, capillary properties, as well as the amount of oil remaining in the formation in the form of films covering the surface of the grains. They are used to guide the operation of wells when selecting filters that prevent the influx of sand, etc. The grain size of most oil-bearing rocks ranges from 0.01 to 0.1 mm. However, usually when studying the granulometric composition of rocks, the following size categories (in mm) are distinguished:
Pebbles, crushed stone > 10
Gravel 10–2
rough 2–1
large 1–0.5
average 0.5–0.25
fine 0.25–0.1
Siltstone:
large 0.1–0.05
fine 0.05–0.1
Clay particles< 0,01
Particles up to approximately 0.05 mm in size and their quantity are determined by sieving on a set of sieves of the appropriate size, followed by weighing the residue on the sieves and determining the ratio (in %) of their mass to the mass of the initial sample. The content of smaller particles is determined by sedimentation methods.
The heterogeneity of rocks in terms of mechanical composition is characterized by a heterogeneity coefficient - the ratio of the particle diameter of the fraction, which with all smaller fractions is 60% by weight of the total mass of sand, to the diameter of the particles of the fraction, which with all smaller fractions is 10% by weight of the total mass of sand ( d60/d10). For “absolutely” homogeneous sand, all grains of which are the same, the heterogeneity coefficient Kn = d60/d10 = 1; Kn for oil field rocks ranges from 1.1–20.
The ability of rocks to allow liquids and gases to pass through is called permeability. All rocks are permeable to one degree or another. Given the existing pressure differences, some rocks are impermeable, others are permeable. It all depends on the size of the communicating pores and channels in the rock: the smaller the pores and channels in the rocks, the lower their permeability. Typically, the permeability in the direction perpendicular to the bedding is less than its permeability along the bedding.
Pore channels are super- and subcapillary. In supercapillary channels, the diameter of which is more than 0.5 mm, liquids move, obeying the laws of hydraulics. In capillary channels with a diameter of 0.5 to 0.0002 mm, when liquids move, surface forces appear (surface tension, capillary forces of adhesion, adhesion, etc.), which create additional forces of resistance to the movement of liquid in the formation. In subcapillary channels having a diameter of less than 0.0002 mm, the surface forces are so great that there is practically no movement of liquid in them. Oil and gas horizons mainly have capillary channels, while clay horizons have subcapillary channels.
There is no direct relationship between porosity and permeability of rocks. Sandy formations can have a porosity of 10–12%, but be highly permeable, while clay formations with a porosity of up to 50% remain practically impermeable.
For the same rock, the permeability will vary depending on the quantitative and qualitative composition of the phases, since water, oil, gas or mixtures thereof can move through it. Therefore, to assess the permeability of oil-bearing rocks, the following concepts are adopted: absolute (physical), effective (phase) and relative permeability.
Absolute (physical) permeability is determined by the movement of one phase (gas or homogeneous liquid in the rock in the absence of physicochemical interaction between the liquid and the porous medium and the pores of the rock being completely filled with gas or liquid).
Effective (phase) permeability is the permeability of a porous medium for a given gas or liquid when the pores contain another liquid or gaseous phase. Phase permeability depends on the physical properties of the rock and the degree of saturation with liquid or gas.
Relative permeability is the ratio of effective permeability to absolute permeability.
A significant part of reservoirs is heterogeneous in texture, mineralogical composition and physical properties vertically and horizontally. Sometimes significant differences in physical properties are found at short distances.
Under natural conditions, i.e. under conditions of pressure and temperature, the permeability of cores is different than under atmospheric conditions; it is often irreversible when reservoir conditions are created in the laboratory.
Sometimes the capacity of a reservoir and the commercial reserves of oil and gas in a formation are determined by the volume of fractures. These deposits are confined mainly to carbonate and sometimes to terrigenous rocks.
Usually, there is no strict pattern in the distribution of fracturing systems among the structural elements to which oil and gas-containing deposits are confined.
To assess permeability, the practical unit Darcy is usually used, which is approximately 10-12 times less than the permeability of 1 m2.
The permeability unit of 1 darcy (1 D) is taken to be the permeability of such a porous medium, when filtering through a sample of 1 cm2 in area and 1 cm in length with a pressure drop of 1 kg/cm2, the flow rate of a liquid with a viscosity of 1 cP (centipoise) is 1 cm3/s. A value equal to 0.001 D is called millidarcy (mD).
The permeability of oil and gas reservoir rocks varies from several millidarcies to 2–3 D and is rarely higher.
There is no direct relationship between permeability and porosity of rocks. For example, fractured limestones, which have low porosity, often have high permeability and, conversely, clays, sometimes characterized by high porosity, are practically impermeable to liquids and gases, since their pore space is composed of subcapillary-sized channels. However, based on average statistical data, it can be said that more permeable rocks are often more porous.
The permeability of a porous medium depends primarily on the size of the pore channels that make up the pore space.
2. Separators, purpose, design, principle of operation and maintenance.
During production and transportation, natural gas contains various types of impurities: sand, weld sludge, heavy hydrocarbon condensate, water, oil, etc. The source of natural gas pollution is the bottomhole zone of the well, which gradually collapses and pollutes the gas. Gas preparation is carried out in fields, the efficiency of which determines the quality of the gas. Mechanical impurities enter the gas pipeline, both during its construction and during operation.
The presence of mechanical impurities and condensate in gas leads to premature wear of the pipeline, shut-off valves, supercharger impellers and, as a consequence, a decrease in the reliability and efficiency of operation of compressor stations and the gas pipeline as a whole.
All this leads to the need to install various process gas purification systems at the compressor station. At first, oil dust collectors were widely used for gas purification at compressor stations (Fig. 3), which provided a fairly high degree of purification (up to 97-98%).
Oil dust collectors operate on the principle of wet capture of various types of mixtures found in gas. Impurities moistened with oil are separated from the gas flow, the oil itself is cleaned, regenerated and again sent to the oil dust collector. Oil dust collectors were often made in the form of vertical vessels, the principle of operation of which is well illustrated in Fig. 3.
The gas being purified enters the lower section of the dust collector, hits the bumper visor 4 and, in contact with the surface of the oil, changes the direction of its movement. In this case, the largest particles remain in the oil. At high speed, the gas passes through the contact tubes 3 into the settling section II, where the gas speed sharply decreases and dust particles flow through the drainage tubes into the lower part of the dust collector I. Then the gas enters the breaker section III, where the final purification of the gas occurs in the separator device 1.
The disadvantages of oil dust collectors are: the presence of constant irreversible oil consumption, the need to clean the oil, as well as heating the oil under winter operating conditions.
Currently, at compressor stations, cyclone dust collectors are widely used as the first stage of cleaning, operating on the principle of using inertial forces to capture suspended particles (Fig. 4).
Cyclone dust collectors are easier to maintain than oil-based ones. However, the cleaning efficiency in them depends on the number of cyclones, as well as on ensuring that the operating personnel operate these dust collectors in accordance with the mode for which they are designed.
The cyclone dust collector (Fig. 4) is a cylindrical vessel designed for the operating pressure in the gas pipeline, with cyclones 4 built into it.
The cyclone dust collector consists of two sections: the lower breaker 6 and the upper precipitation 1, where the final purification of gas from impurities occurs. The lower section contains cyclone pipes 4.
Gas through the inlet pipe 2 enters the apparatus to the distributor and the star-shaped cyclones 4 welded to it, which are fixedly fixed in the lower grid 5. In the cylindrical part of the cyclone pipes, the gas, supplied tangentially to the surface, rotates around the internal axis of the cyclone pipes. Under the action of centrifugal force, solid particles and liquid droplets are thrown from the center to the periphery and flow along the wall into the conical part of the cyclones and then into the lower section 6 of the dust collector. The gas after the cyclone tubes enters the upper settling section 1 of the dust collector, and then, already purified, exits the apparatus through pipe 3. During operation, it is necessary to control the level of separated liquid and solid impurities in order to remove them in a timely manner by blowing through the drainage fittings. Level control is carried out using sight glasses and sensors attached to fittings 9. Hatch 7 is used for repair and inspection of the dust collector during scheduled shutdowns of the compressor station. The efficiency of gas purification with cyclone dust collectors is at least 100% for particles with a size of 40 microns or more, and 95% for droplet liquid particles.
Due to the impossibility of achieving a high degree of gas purification in cyclone dust collectors, it becomes necessary to perform a second stage of purification, which is used as filter separators installed in series after the cyclone dust collectors (Fig. 5)
The operation of the filter separator is carried out as follows: the gas after the inlet pipe is directed, using a special fender, to the inlet of filter section 3, where the liquid is coagulated and cleaned from mechanical impurities. Through perforated holes in the housing of the filter elements, gas enters the second filter section - the separation section. In the separation section, the gas is finally purified from moisture, which is captured using mesh bags. Through drainage pipes, solids and liquid are removed into the lower drainage collection and further into underground containers.
To operate in winter conditions, the filter-separator is equipped with electric heating of its lower part, a condensate collector and control and measuring equipment. During operation, mechanical impurities are captured on the surface of the filter separator. When the difference reaches 0.04 MPa, the filter separator must be turned off and the filter elements replaced with new ones.
As experience in the operation of gas transmission systems shows, the presence of two degrees of purification is mandatory at underground gas storage stations, as well as at the first linear compressor station along the route that receives gas from an underground gas storage facility. After cleaning, the content of mechanical impurities in the gas should not exceed 5 mg/m3.
Gas supplied to the head compressor stations from wells, as noted, almost always contains moisture in the liquid and vapor phases in varying quantities. The presence of moisture in gas causes corrosion of equipment and reduces the throughput of the gas pipeline. When interacting with gas under certain thermodynamic conditions, solid crystalline substances-hydrates are formed, which disrupt the normal operation of the gas pipeline. One of the most rational and economical methods of combating hydrates with large pumping volumes is gas drying. Gas drying is carried out by devices of various designs using solid (adsorption) and liquid (absorption) absorbers.
With the help of gas drying units at head structures, the content of water vapor in the gas is reduced, and the possibility of condensation in the pipeline and the formation of hydrates is reduced.
3. Systems and schemes for gas collection and transportation, their advantages and disadvantages
cancelled/lost force Editorial from 02.09.1997
| Name of document | "RULES FOR THE CONSTRUCTION AND SAFE OPERATION OF VESSELS OPERATING UNDER PRESSURE. PB 10-115-96" (approved by Resolution of the State Gortechnadzor of the Russian Federation dated 04/18/95 N 20) (as amended on 09/02/97) |
| Document type | resolution, list, rules |
| Receiving authority | Gosgortekhnadzor of the Russian Federation |
| Document Number | 20 |
| Acceptance date | 01.01.1970 |
| Revision date | 02.09.1997 |
| Date of registration with the Ministry of Justice | 01.01.1970 |
| Status | cancelled/lost force |
| Publication |
|
| Navigator | Notes |
"RULES FOR THE CONSTRUCTION AND SAFE OPERATION OF VESSELS OPERATING UNDER PRESSURE. PB 10-115-96" (approved by Resolution of the State Gortechnadzor of the Russian Federation dated 04/18/95 N 20) (as amended on 09/02/97)
5.3. Pressure gauges
5.3.1. Each vessel and independent cavities with different pressures must be equipped with direct-acting pressure gauges. The pressure gauge is installed on the vessel fitting or pipeline between the vessel and the shut-off valve.
5.3.2. Pressure gauges must have an accuracy class of at least: 2.5 - at a vessel operating pressure of up to 2.5 MPa (25 kgf/sq. cm), 1.5 - at a vessel operating pressure above 2.5 MPa (25 kgf/sq. cm ).
5.3.3. The pressure gauge must be selected with a scale such that the limit for measuring working pressure is in the second third of the scale.
5.3.4. The owner of the vessel must mark the pressure gauge scale with a red line indicating the operating pressure in the vessel. Instead of the red line, it is allowed to attach a metal plate painted red to the pressure gauge body and tightly adjacent to the glass of the pressure gauge.
5.3.5. The pressure gauge must be installed so that its readings are clearly visible to operating personnel.
5.3.6. The nominal diameter of the body of pressure gauges installed at a height of up to 2 m from the level of the observation platform must be at least 100 mm, at a height of 2 to 3 m - at least 160 mm.
Installation of pressure gauges at a height of more than 3 m from the site level is not permitted.
5.3.7. A three-way valve or a device replacing it must be installed between the pressure gauge and the vessel, allowing periodic checking of the pressure gauge using a control valve.
In necessary cases, the pressure gauge, depending on the operating conditions and the properties of the medium in the vessel, must be equipped with either a siphon tube, or an oil buffer, or other devices that protect it from direct exposure to the medium and temperature and ensure its reliable operation.
5.3.8. On vessels operating under pressure above 2.5 MPa (25 kgf/sq. cm) or at ambient temperatures above 250 degrees. C, as well as with an explosive atmosphere or harmful substances of hazard classes 1 and 2 according to GOST 12.1.007, instead of a three-way valve, it is allowed to install a separate fitting with a shut-off device for connecting a second pressure gauge.
On stationary vessels, if it is possible to check the pressure gauge within the time limits established by these Rules by removing it from the vessel, the installation of a three-way valve or a device replacing it is not necessary.
On mobile vessels, the need to install a three-way valve is determined by the vessel design developer.
5.3.9. Pressure gauges and pipelines connecting them to the vessel must be protected from freezing.
5.3.10. The pressure gauge is not allowed for use in cases where:
there is no seal or stamp indicating verification;
the verification period has expired;
when it is turned off, the arrow does not return to the zero scale reading by an amount exceeding half the permissible error for this device;
the glass is broken or there is damage that may affect the accuracy of its readings.
5.3.11. Checking of pressure gauges with their sealing or branding must be carried out at least once every 12 months. In addition, at least once every 6 months, the owner of the vessel must carry out an additional check of the working pressure gauges with a control pressure gauge and record the results in the control check log. In the absence of a control pressure gauge, it is allowed to carry out an additional check with a proven working pressure gauge that has the same scale and accuracy class as the pressure gauge being tested.
The procedure and timing for checking the serviceability of pressure gauges by maintenance personnel during the operation of vessels should be determined by the Instructions for the operation mode and safe maintenance of vessels, approved by the management of the organization that owns the vessel.
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Grade 5+A pressure gauge is a special device that is designed to measure pressure. Such devices come in various types and are installed in different ways. Let's look at them in detail.
Methods for installing pressure gauges
Direct installation method
A pressure gauge with special threaded seals is immediately screwed onto the pre-welded adapter. This method is considered the most affordable and is used to operate the device in a stable environment without strong pressure surges and without constant device replacements.
Installation method on a three-way valve
A three-way valve is screwed onto the pre-welded adapter using threaded connections, and a pressure gauge is screwed into it. A similar method is used if it is necessary to switch the device to atmospheric pressure using this tap when checking the readings.
The latter allows you to change the device without interrupting the operating cycle, or carry out pressure testing of the system and other work that is associated with an increase in pressure in the system.
Installation method using an impulse tube 
In addition to the two methods listed above, the pressure gauge is also installed through an impulse tube, which can protect the sensitive mechanism of the device from damage.
To install a pressure gauge using this method, you should screw the impulse tube vertically onto a pre-welded adapter, attach a three-way valve and the pressure gauge itself.
The pulse tube is used in situations where the steam has a temperature that exceeds the possible norm of the measured parameters. It prevents the pressure gauge from coming into contact with hot steam.
What rules must be followed when installing pressure gauges?
- The pressure gauge should be mounted in such a way that the readings are clearly recognizable. The scale is located vertically or has an inclination of 30°.
- The diameter of the device body, mounted at a height of up to two meters from the platform level, cannot be less than 100 mm, from two to three meters - not less than 160 mm. Installation of the device at a height of more than 3 m from the site level is strictly prohibited.
- Any pressure gauge must be well illuminated and protected from the rays of the sun and frost.
- When installing the pressure gauge, it is necessary to tighten it on the tee, without reaching the device itself, in order to release the air.
- The pressure gauge cannot be used if it does not have a seal with a mark indicating that the test was carried out, the period for this test has expired, the needle of the device (when it is turned off) does not reach zero, the glass is broken, or there is even the slightest damage to the device.
If you discover a malfunction of the device, you should send it in for repairs, having first cleaned it of dirt and rust.
Thus, if you need to install a pressure gauge, be sure to contact a specialist. The installation of this device must be strictly carried out by a qualified employee of the organization using special equipment.
When installed remotely, the pressure gauge is connected to the sampling device via a pulse pipeline. In Fig. 64.6 installation of pressure gauges, a diagram of a pipeline for measuring the pressure of aggressive liquids is shown, and in Fig. 64, in - pair.
A separation vessel 5 is connected to the object (pipeline) 1 through a valve 10, to which an impulse pipeline 15 is connected through a valve 7. The pipeline has a vertical pipe, to which branches with a slope of 1:10 are suitable. The upper part of the vertical pipe is used to collect gases (gas collector), which are discharged through valve 11. The lower part of the pipe is used to collect sludge, which is drained through valve 12. On air and gas impulse pipelines, this part is called a condensate collector. Device 4 is connected to the pipeline through a three-way valve 3. Valves 8 and 9 are used to drain and fill the vessel, and valve 6 is used to control the level of the separating liquid.
The liquid separating impulse pipeline and the separating vessel 5 are filled in the sequence described below. The pipeline is purged with compressed air. The liquid is pumped through valve 12, located at the lowest point of the impulse pipeline. When the liquid flows through valve 6, the separation vessel is turned off (close valve 7). Filling continues until the liquid flows through tap 11 located at the top point of the pipeline.
After this, the vessel is filled with the measured liquid through tap 9. Connect the vessel to the medium being measured and connect the device (open taps 10, 7, 3).
On steam mains, equalization vessel 13 and the pulse pipeline are filled with condensate in 30...40 minutes with valve 10 open. Valve 14 is periodically opened, and when the condensate drains from it, valve 3 is connected to the device.
If there is a significant difference in the ΔН levels of the sampling site and the installation site of the pressure gauge, it is necessary to introduce a correction Δp=c*ΔН into the instrument readings (c is the specific gravity of the liquid filling the impulse pipeline).
Therefore, in order not to introduce a correction, as well as for large measurement distances, a set consisting of a scaleless pressure gauge with an electric or pneumatic GSP output signal is used.
Scaleless pressure gauges (pressure meters, draft meters) are installed on cabinets or special metal structures. In Fig. 65a shows the installation of an MME membrane electric pressure gauge.
Pressure gauges are designed to convert the pressure of liquids and gases into an electrical current signal of 0...5 mA. Complete with a pressure gauge, a secondary device KSU, “Disk-250” or another monitoring and control device with a corresponding output signal can work. The device is mounted on bracket 1 (or other mounting platform). The body 2 of the device is secured with bolts 3. Deviation from the vertical is no more than 1...2°. The measured pressure is applied to fitting 4. To do this, unscrew the union nut 5 and disconnect the fitting. Weld it to the impulse pipe and mount the assembly in place. Power supply 220 V 50 Hz is supplied to the device by cable through gland 6, and the output signal cable through gland 7. The connecting terminals are located inside the terminal box 8.
In Fig. 65.6 installation of scaleless pressure gauges, shows the installation of a bellows pressure meter 1 with a pneumatic output signal of 20...100 kPa (0.2...1 kgf/mm 2) on a pipe or on a stand made of pipe 2. The measured pressure is supplied to fitting 3 , and the power supply pipeline and the output signal pipeline are connected to fittings 4 and 5.
Pressure alarms can be scaleless (pressure sensors and switches). For example, DD, RD-1, etc., or built into measuring instruments - 717 Cr, etc. with electric or pneumatic outputs.
Pressure sensors are installed on tripods and metal structures, and measuring instruments are mounted on panels. The units are either raised or recessed mounted, similar to those shown in rice. 58. Installation of impulse pipes, power supply and output signal pipes, cable lines for signaling circuits and power supply of recorders is carried out in the same way as in the cases described above.