The following are common types of compressors used for casing gas recovery:
Reciprocating compressor
Working principle: By reciprocating the piston in the cylinder, the cylinder volume periodically changes, thereby achieving the process of gas suction, compression, and discharge. When the piston moves outward, the pressure inside the cylinder decreases and gas is sucked in; When the piston moves inward, the gas inside the cylinder is compressed, the pressure increases, and then discharged through the exhaust valve.
characteristic:
Wide range of pressure adaptation: high compression ratio, single-stage pressure ratio can reach more than 10, able to adapt to pressure ranges from low pressure to high pressure or even ultra-high pressure, suitable for situations where the initial pressure of casing gas is low but needs to be compressed to a higher pressure.
Flexible flow regulation: A wide range of flow regulation can be achieved by adjusting the piston stroke, speed, or number of cylinders, which can better adapt to changes in the gas flow rate of the casing.
Strong adaptability to gases: It has good tolerance to gas composition and impurities, and can handle casing gases containing certain impurities. However, the discharged gas may contain oil stains. For recovery processes that require high gas quality, it may be necessary to increase gas purification equipment.
Application scenario: Suitable for casing gas recovery with small to medium flow rates, large pressure variation ranges, complex gas compositions, and certain impurities. It is commonly used in small oil wells or situations where flow requirements are not high.
Screw compressor
Working principle: A pair of interlocking male and female rotors rotate inside the casing, causing gas to be drawn in from the inlet. As the rotors rotate, the volume of gas between the rotors and the casing continuously decreases, thereby achieving gas compression and finally being discharged from the exhaust port.
characteristic:
Smooth operation: compact structure, small size, light weight, smooth operation, low vibration, low noise, low foundation requirements, can achieve no foundation operation, especially suitable for use as a mobile compressor, easy to adjust and use between different oil wells.
Wide flow range: With a wide flow range and a single machine capacity of over 1000kW, it can meet the gas recovery needs of medium to high flow casing, and maintain high efficiency within a wide operating range.
Has a certain tolerance to impurities: insensitive to wet stroke, can transport multiphase mixed gases such as liquid containing gas, dust containing gas, and easily polymerized gas, suitable for situations where casing gas may contain a small amount of liquid or impurities, but has certain requirements for gas cleanliness and needs to be equipped with effective intake filtration devices.
Application scenario: Suitable for casing gas recovery in the medium and low pressure range, medium to large flow rates, high requirements for operational stability, and with a small amount of impurities in the gas. It is widely used in casing gas recovery in various oil wells.
Centrifugal compressor
Working principle: With the high-speed rotation of the impeller, the gas obtains kinetic energy and pressure energy under the action of centrifugal force. The gas enters from the center of the impeller, and as the impeller rotates, the gas is thrown towards the edge of the impeller, increasing in speed and pressure. Then, the gas velocity is further reduced by components such as a diffuser, converting kinetic energy into pressure energy, thereby achieving gas compression and discharge.
characteristic:
High efficiency with high flow rate: With a large air volume and a single machine capacity of over 5000kW, it is suitable for high flow casing gas recovery. Under high flow rate and medium high pressure conditions, it has good energy efficiency, high mechanical efficiency, and low energy consumption.
Stable and reliable operation: extremely high speed, high mechanical efficiency, smooth operation, low noise, oil-free lubrication, clean exhaust, no need for oil separation, low basic requirements.
High requirements for gas quality: suitable for processing relatively clean and non corrosive gases, with high requirements for gas quality and composition. If the casing gas contains impurities or corrosive components, it may cause damage to components such as impellers and diffusers, affecting the performance and lifespan of the compressor.
Application scenario: Suitable for casing gas recovery with high flow rate, medium high pressure, and relatively clean gas, commonly used in centralized processing stations of large oil wells or oil and gas fields with high requirements for flow rate and pressure.
Diaphragm compressor
Working principle: By reciprocating the diaphragm in the cylinder, the cylinder volume is changed to achieve gas compression. The diaphragm divides the cylinder into two chambers, one is the hydraulic oil chamber and the other is the gas chamber. The pressure of the hydraulic oil drives the diaphragm to move, thereby compressing the gas.
characteristic:
Good sealing: Due to the diaphragm completely separating gas from hydraulic oil, it avoids contact between gas and lubricating oil, resulting in high purity and no oil stains in the discharged gas. It is particularly suitable for sleeve gas recovery processes that require extremely high gas quality.
Pressure Stability: Able to provide stable exhaust pressure with minimal pressure fluctuations, suitable for casing gas recovery systems that require precise pressure control.
Low maintenance cost: The structure is simple, there are no worn parts, and there is no need to replace vulnerable parts such as piston rings and air valves. The maintenance workload is small and the maintenance cost is low.
Application scenario: Suitable for casing gas recovery with low flow rate, high pressure, and high requirements for gas purity and pressure stability, especially in special applications with strict gas quality requirements, such as electronic gas production, it has unique advantages. However, its application in casing gas recovery in the oil and gas industry is relatively limited.
The following are the approximate price ranges for different types of casing gas recovery compressors:
Reciprocating compressor
Small: A small reciprocating compressor with a power of less than 10kW, usually priced at around 20000 to 50000 yuan. This type of small compressor is suitable for small oil wells with lower production rates. Its processing capacity is relatively small, but its structure is simple and easy to operate.
Medium sized: A medium-sized reciprocating compressor with a power between 10kW and 50kW, priced at approximately 50000 to 150000 yuan. This type of compressor can meet the casing gas recovery needs of medium production oil wells, with a certain pressure and flow range that can be adjusted according to specific operating conditions.
Large: Large reciprocating compressors with a power of over 50kW are usually priced at over 150000 yuan or even higher. Large reciprocating compressors are suitable for high-yield oil wells and can handle large gas flow rates and high pressures, but the equipment volume is relatively large and the cost is also relatively high.
Screw compressor
General specifications: A common screw compressor with a power of between 30kW and 100kW, priced at approximately 100000 to 300000 yuan. This specification of screw compressor is widely used in casing gas recovery, able to adapt to a certain range of flow and pressure changes, and has the advantages of smooth operation and low noise
Large high-performance: Large high-performance screw compressors with a power of over 100kW may cost over 300000 yuan, or even over 500000 yuan. This type of compressor has higher flow and pressure output, making it suitable for large-scale casing gas recovery projects, but the equipment cost and maintenance requirements are also correspondingly high.
Centrifugal compressor
Medium and small flow rate: For centrifugal compressors with medium and small flow rates, the power is generally between 50kW and 200kW, and the price is about 200000 yuan or 500000 yuan. This centrifugal compressor is applied in some local recovery systems of medium-sized oil wells or oil and gas fields, and can provide relatively stable gas compression services.
High flow and high pressure: Centrifugal compressors with high flow and high pressure typically have a power of over 200kW and a relatively high price, usually around 500000 yuan, 1 million yuan, or even higher. This type of compressor is mainly used in centralized processing stations for large oil and gas fields that require extremely high flow and pressure requirements. However, due to its high technical content and complex manufacturing process, its price is relatively expensive.
Diaphragm compressor
Small flow high pressure: Diaphragm compressors with small flow and high pressure, with a power of less than 10kW, are generally priced at around 50000 yuan or 100000 yuan. This diaphragm compressor is suitable for small casing gas recovery projects that require extremely high gas purity and pressure stability. Although the flow rate is small, it can meet specific process requirements.
Medium flow: A medium flow diaphragm compressor with a power between 10kW and 30kW, priced at approximately 100000 to 200000 yuan. This type of compressor can be used in some casing gas recovery applications that require strict gas quality and moderate flow rate, but its application is relatively less widespread than other types of compressors in the entire casing gas recovery market.
