Technology and Diagrams

Technology:

The basic technological components of the underground gas storage facility are:

- deposit (naturally occurring porous and permeable stone in whose pores, that is, microscopic cavities, gas is stored),
- wells (to reach deposits located at depths of over one kilometer and above ground plant),
- compressor plant (which serves to inject natural gas from the transport system into the deposit),
- pipelines (interconnect the above ground plants and wells),
- gas preparation plant (serves for the preparation of gas for transport and measuring).

The Okoli plant is technologically connected with the main gas pipeline of the Republic of Croatia, while the technology process that takes place in the underground gas facility occurs in two cycles:
a) the gas injection cycle;
b) the gas withdrawal cycle;

In the gas injection cycle, gas from the main gas pipeline passes through an input-output separator at an average pressure of 30-40 bar, and comes to the measuring reduction station of the plant, where, after passing through a filter of solid particles, gas is measured with ultrasound and turbine flow meters.

The total injection capacity amounts to 160 000 m³/h, while maximum pressure at compressor output amounts to 196 bar.

The deposits are surrounded by aquifers and lie at an average depth of 1825 to 1870 meters.

The gas withdrawal cycle from the storage facility takes place in the period from October to April. Gas withdrawal takes place on 6 drilling platforms (PF-1, PF-2, PF-3, PF-4, PF-5, PF-6) that are connected to connecting pipelines with the central plant. Each platform consists of a certain number of wells, from which gas is withdrawn from deposits in which it is injected during the injection cycle.

The complete gas operations system is automated, and it is controlled and managed from the control room in the PSP Okoli plant.

Scheme: