The recovery and utilization of wellhead gas is an important energy and resource utilization link, especially in the field of oil and gas exploration and development. The following is a detailed analysis of the recovery and utilization of wellhead gas:
1. Composition and characteristics of wellhead gas
Wellhead gas mainly includes natural gas (mainly composed of methane), associated gas (gas produced simultaneously with oil extraction), and other possible gas components. These gases typically have high energy value and recycling helps reduce carbon emissions and environmental pollution.
2. Recovery and utilization methods of wellhead gas
Natural gas recovery
Conventional recycling: By laying gas gathering pipelines, natural gas from the wellhead is collected and transported to downstream processing plants for processing and utilization. This method is suitable for areas with concentrated well clusters and abundant resources.
Unconventional recycling: For scattered and remote unconventional natural gas wells, due to the difficulty in laying pipeline networks, CNG (compressed natural gas) devices can be used for recycling. However, attention should be paid to issues such as long equipment installation cycles and large land occupation, and equipment specifications should be replaced in a timely manner according to the gas volume to meet the production needs of the well site.
Associated gas recycling
Underground separation and recovery: The gas in the produced liquid is separated underground using an underground separator, and then lifted in sections through an intelligent gas distribution valve to allow the gas to enter the annulus and be recovered. This method saves energy, improves pump efficiency, and avoids the impact of harsh ground environments.
Reinjection into the wellbore: Inject dry gas and ethane from associated gas back into the wellbore to maintain downhole pressure and explore the possibility of secondary extraction. But this method is still in the experimental stage and requires multiple steps such as processing, separation, aggregation, and pressurized injection.
Other gas recovery
For other valuable gases generated at the wellhead (such as hydrogen, helium, etc.), corresponding separation and recovery technologies can be used for extraction and utilization.
3. The value and significance of wellhead gas recovery and utilization
Energy conservation: Recycling wellhead gas can reduce reliance on traditional energy sources and improve energy efficiency.
Resource utilization: Wellhead gas itself is a valuable resource, and recycling can avoid resource waste.
Environmental protection and emission reduction: By recycling wellhead gas, carbon emissions and environmental pollution can be reduced, which helps achieve sustainable development goals.
4. Challenges and Solutions
Technical challenge: The recovery of unconventional natural gas wellhead gas faces technical difficulties, such as complex equipment, long installation cycles, and low recovery efficiency. The solution includes developing new recycling devices and processes to improve recycling efficiency and flexibility.
Economic challenge: The recovery and utilization of wellhead gas requires significant investment in equipment procurement and installation, and the recovery cost may be high. The solution includes government providing policy support (such as tax incentives, subsidies, etc.) and attracting social capital participation.
Environmental challenge: Secondary pollution such as wastewater and exhaust gas may occur during the recycling process. The solution includes strengthening environmental supervision and pollution control measures to ensure the environmental friendliness and safety of the recycling process.
In summary, the recovery and utilization of wellhead gas have important economic and social significance. By adopting advanced recycling technologies and processes, strengthening policy support and social capital participation, and enhancing environmental supervision, the healthy development of the wellhead gas recycling industry can be promoted.
The recovery and utilization technologies of wellhead gas mainly include the following:
1. Liquid processing technology
The natural gas at the wellhead is liquefied through compression and cooling in the recovery device to change its state, making it easier to store and transport. Liquefied natural gas (LNG) is an important trend in the future development of energy technology, with advantages such as high efficiency, cleanliness, and environmental protection.
2. Storage technology of gas storage tank
By applying pressure to compress and store natural gas at the wellhead in a storage tank, reliable energy supply can be achieved. Gas storage tanks are an effective way to store natural gas at wellhead, widely used in industrial and transportation fields.
3. Cogeneration technology
By using thermoelectric equipment to burn natural gas at the wellhead to generate electricity, while recovering the heat energy from the exhaust gas for heating or cooling. This method can improve the utilization efficiency of natural gas at the wellhead and reduce its impact on the environment. Cogeneration technology is of great significance in the comprehensive utilization of energy and energy conservation and emission reduction.
4. Wellhead casing gas recovery technology
The recovery of associated gas from oil fields (mainly composed of methane) mainly includes the following technologies:
Antifreeze blocking wellhead casing gas constant pressure relief valve recovery technology: suitable for oil wells with casing pressure greater than back pressure. By designing a process structure that combines a one-way valve with a constant pressure exhaust component, a pressure regulation method is developed to solve the problems of throttling cooling, winter freezing blockage, and direct reading pressure regulation.
Low pressure casing gas recovery and emission reduction technology: For oil wells with casing pressure lower than back pressure, an innovative anti backflow casing gas recovery device or oil well wellhead casing gas boosting recovery device is designed based on the difference between casing pressure and back pressure. Based on the self suction motion of the oil well, effective recovery of casing gas is achieved.
Underground separation and recovery technology: The gas in the produced liquid is separated underground using an underground separator. After entering the annulus of the oil well, the separated gas uses its own energy and is lifted in sections through an intelligent gas distribution valve to achieve the optimal lifting depth, allowing the oil well to achieve the effect of "continuous pumping and spraying". This technology not only recovers associated gas but also saves energy and improves pump efficiency.
5. Fully automatic recycling process
This process is based on the actual situation of the well site, and a fully automatic recovery process for associated gas at the wellhead is designed. The associated gas enters the recovery pipeline through the casing, undergoes filtration, settling separation, compression and other steps, and finally flows back to the gathering pipeline. The fully automatic recycling process adopts a pry structure, dividing each process equipment into independent multiple units for easy disassembly and combination, suitable for various technical requirements and environmental conditions. This process not only achieves the goals of resource recovery and energy conservation, but also has considerable economic benefits.
6. Eccentric wellhead casing gas recovery technology
The eccentric wellhead casing gas recovery device is installed on the eccentric wellhead of the oil well and can fully recover casing gas. After the associated gas enters the casing, when the pressure reaches a certain value, the pressure control valve can be pushed open, and then it enters the oil pipe channel through the recovery channel for recovery. The pressure control function of the pressure control valve can maintain a constant pressure inside the casing and prevent the liquid in the oil pipe hole from flowing back into the annular space of the casing during the casing gas recovery process.
7. Gas gathering pipeline recovery technology
For oil wells with concentrated well clusters, abundant associated gas resources, and close proximity to oil transfer stations and light hydrocarbon plants, the method of directly laying pipelines is adopted to recover casing gas. This method is simple, direct, and easy to operate and manage.
In summary, there are various technologies for the recovery and utilization of wellhead gas, and suitable technologies should be selected according to the actual situation to improve energy utilization efficiency, reduce environmental pollution, and achieve sustainable development.
