The natural decline in reservoir pressure and hydrocarbon withdrawal from productive horizons has led to a decrease in pressure at the wellheads of the Sakhalin field. This process makes it virtually impossible to simultaneously meet the quality and production targets for gas treatment using the existing low-temperature separation method.

To ensure stable production performance, as well as high-quality gas treatment in accordance with the requirements of the Gas Transmission System Code, UNB reconstructed the gas treatment system with the introduction of artificial cold. In September 2020, a new propane refrigeration unit (PRU) was put into operation. Its purpose is to treat gas by low-temperature separation using artificial cold produced with R290 refrigerant (99.95% propane). The throughput capacity of this process line allows to treat gas from the Sakhalin field in the amount of up to 2 million m3/day.

The unit consists of two process circuits: a refrigerant circuit (propane circuit) and a low-temperature gas separation circuit. The refrigerant circuit provides a continuous process of artificial cold production. The low-temperature gas treatment circuit ensures high-quality gas treatment in accordance with the requirements of regulatory documents. To ensure hydrate-free operation of the low-temperature gas treatment circuit, monoethylene glycol is supplied with its subsequent collection, regeneration and reuse.

In the process of PCU installation, advanced technological solutions of Ukrainian and foreign equipment manufacturers were implemented.

Manufacturing of the PCU process units with heat exchange and separation equipment was performed by QB Johnson Manufacturing, Inc (USA). GEA screw compressors (Germany) were used in the compressor units. In addition, the latest (latest generation) frequency converters manufactured by ABB (Switzerland/Sweden) were introduced. Electric drives manufactured by ABB are also used in the air-cooling unit of the gas apparatus, and pumps manufactured by Kimray (USA) are used to supply monoethylene glycol.

A 0.4 kV diesel generator station with a nominal capacity of 780 kVA manufactured by Wilson (UK) is provided as a backup power supply to ensure uninterrupted and trouble-free gas treatment at the PCU.

The modern automated process control system of the CCF ensures a continuous gas treatment process, optimizes the product gathering and treatment system and well operation modes. As a result, the unit stabilizes gas production at the Sakhalin field and increases production efficiency by applying advanced and sometimes unique technological solutions for Ukraine

- said Bogdan Kukura, Technical Director of PrJSC MC Ukrnaftoburinnya.