Gas lift fields

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Problem


Associated petroleum gas production continues to grow every year, surpassing the oil production by the factor of 3.5 in terms of growth rate. At the same time, the quality of the mineral resources base is getting worse, the reserves become difficult to recover, and high-viscosity oil fields are being developed. Therefore, growing is the number of fields where the best way to maintain the formation pressure is to inject the gas back into the formation. This reduces the viscosity and density of oil and slightly presses the productive formation with the gas cap. However, this technology is associated with complexities in gas treatment and metering.


Alternatives


Gas lift fields can be operated using either a compressor or compressorless type of technology. Compressor type requires more thorough gas treatment. Compressorless type requires to maintain high pressure of gas; this imposes constraints upon its gathering and treatment infrastructure. The complexity of the injected gas metering is caused by the number of wells to be metered, while the flow rate, both total and for individual wells, may vary subject to the required formation conditions and the formation pressure maintenance technology. In such an environment, a distributed gas supply control and metering system would be too bulky and expensive.


Solution

OZNA developed an injected gas treatment unit bases on low-temperature separation. This will allow for splitting and conditioning the gas streams. For efficient gas metering, we offer a single unit with a backup metering line, a gas line to a pilot, and a system for emergency discharge to a horizontal gas flare unit. The switchboard room is integrated with the process unit due to the positive pressure being created therein by the air pressurization system.


Results


The gas treatment unit provides for efficient and long operation of expensive compressor equipment. The single block box of the metering unit reduces the construction area and capital investments for foundations. The air pressurization system provides for price-efficiency of the explosion protection system. Automated flowrate control allows for provision of the required injection volumes individually for each well. The backup line makes the process flow more flexible.



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