ServicENERGAS carried out a technical audit of the vacuum compressor stations at the three facilities of JSC Gazpromneft-Noyabrskneftegaz

14 December 2019

As part of contract with JSC Gazpromneft-Noyabrskneftegaz, the experts of the service company belonging to the ENERGAS Group carried out a technical audit of the four vacuum compressor stations (VCS) operating at the BPS-1, BPS-2, and BPS-3 of Vyngapur field.

At these facilities, the VCSs form the basis of a system for recovery of APG coming from low separation stages. Process units perform compressing low-pressure (0.001 MPa) associated gas; compressed APG is injected into the gas transportation system under the pressure 0.7 MPa.

As a result of the inspection there were compiled defect sheets, prepared recommendations on replacement of defective and exhausted assemblies and components, drawn up plan for local restoration works and major repair of the stations.

Vacuum CSs are made on the basis of oil-filled screw compressors. The rated capacity of the units is from 1,500 m3 / h to 4,000 m3 / h; gas flow is controlled by a special two-level regulation system. VCSs operate in an automatic mode; local ACSs are integrated with the upper level of APCS.

There are several main issues that make low-pressure APG compression process complicated: need for additional associated gas purification; risk of condensate dropout inside the gas system; negative impact of very low inlet pressure close to the vacuum; changes of the gas composition; severe operating conditions. Therefore, this technological task is solved by special projects – on the basis of a set of consistent engineering solutions.

In particular, the gas final purification at the compressor inlet is performed by a highly efficient two-stage filter-scrubber (with a system of automatic drainage) integrated in the process unit's block-module.

At the design stage, there were carried out a detailed analysis of the gas composition and calculations in special software that creates a theoretical model of the behavior of a gas under certain conditions (temperature and pressure). This made it possible to determine the optimal parameters of operating temperature of oil and gas, which allow compression processes runs out of the condensation zone.

In unit's oil system are used special lubricants with higher viscosity and high resistance to saturation from the heavy hydrocarbons. Suction line is equipped with quick-acting valves with electric actuators and spring failsafe closing devices, that allows to cut off the compressor station gas circuit from the gas inlet pipeline.

VCSs were designed taking into account extreme operating conditions (minimum air temperature – minus 59°C, average temperature of the coldest five-day period – minus 50.5°C). Special alloys and anti-corrosion materials were used in the production. It was performed redundancy of some components and subassemblies of equipment.

Vacuum CSs are housed in its own all-weather enclosures; they are equipped with all necessary life support systems (heating, ventilation, and lighting) and safety systems (fire detection, gas detection, alarm, and fire fighting).

REFERENCE. Vyngapur oil and gas condensate field is located in the Purovsky District of the Yamal-Nenets Autonomous Area. It was discovered in 1968 and has been in commercial development since 1982. It has a well-developed infrastructure. It is one of the largest fields of JSC Gazpromneft-Noyabrskneftegaz and along with Sporyshevskoye, Kholmogorskoye and Chatylkinskoye fields provides the bulk of the company's production.

Gazpromneft-NNG is engaged in oil and gas production activities in the Yamal-Nenets and Khanty-Mansi Autonomous Areas. Taking into account the branch of Gazpromneft-Muravlenko, the company develops more than 30 fields. The main part of the fields is located in the Yamal and territorially related to the Purovsky, Krasnoselkupsky and Nadym Districts of the Area.

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