EFFECT OF ASSOCIATED PETROLEUM GAS ON THE RATE OF HYDROCARBON С3+ RECOVERY IN CO-TREATMENT WITH GAS CONDENSATE FEEDSTOCK

Abstract

Relevance. In Tomsk region there are favorable conditions for implementing such efficient way to use associated petroleum gas, as its co-treatment with natural gas applying the technique of low-temperature separation. This direction is supposed to be developed. The сompany «Gazpromneft-Vostok» is implementing a large-scale investment project aimed at achieving a 95 % level of beneficial use of associated petroleum gas from the cluster of the fields. The gas produced at this cluster will be directed to the gas and condensate treatment plant at Myldzhinskiy oil and gas condensate field. On the other hand, for treatment of gas from gas-condensate fields, the crucial task is to increase the yield of the stabilized hydrocarbon condensate. To solve this problem, it is necessary to optimize the process schemes of low-temperature separation based on the component gas compositions. Therefore, the relevant topic is to study the effect of petroleum gas on the rate of recovery of condensing components in the treatment of a mixture of gases of different origins. The main aim of the research is to determine the effect of associated petroleum gas on the rate of hydrocarbon recovery C3-4 and C5+ in gas co-treatment of gas-condensate and oil fields based on low-temperature separation. The object of the research is an integrated gas and condensate treatment plant. Method: modeling with a software package Aspen HYSYS. Results. Dry gas from the natural gas field has the maximum expander effect: 11–22 °C/MPa. Decrease in methane content of gases in the gas condensate and oil fields leads to reduction of the expander effect. When lowering gas temperature before the expander from minus 5°C to minus 20°C the expander effect value decreases for the gases of the gas and gas condensate fields, but increases for the gases of oil fields. Co-treatment of associated petroleum and natural gases allows eliminating the retrograde condensate evaporation. Co-treatment of the studied gas condensate and associated petroleum gases at a pressure of 6 MPa before the expander increases the recovery rate of C5+ hydrocarbons into unstable condensate by 1.9%, but decreases the recovery rate of C3-4 hydrocarbons by 7.9% relative to the expected values.

Keywords

• natural gas
• associated petroleum gas
• low-temperature separation
• composition
• recovery rate
• condensate