EVALUATION OF TEMPERATURE AND PRESSURE CONDITIONS EFFECT ON LOW-TEMPERATURE ABSORPTION EFFECTIVENESS AT GAS TREATMENT ON THE FAR NORTH FIELD

Abstract

Relevance. Gas condensate is a valuable raw material for oil refining and petrochemical production, therefore an increase in the degree of its extraction from gas of the gas condensate fields at field installations is an important scientific and technical problem. The aim of the study is to substantiate the possibility of increasing the yield of unstable condensate – C3 + fraction from the gas stream at operating complex gas and condensate treatment plant of one of the oil and gas condensate fields in the Far North by changing the operating parameters of the low-temperature absorption. The object: field plant of low-temperature absorption. Method: simulations of separation and low-temperature absorption in the software package «PetroSim». Results. The authors have studied the influence of pressure and temperature, gas flow, specific flow rate and composition of the absorbent – unstable condensate, on the efficiency of the gas and condensate preparation at complex gas and condensate treatment plant computer model of low-temperature absorption and low-temperature separation. It is shown that the low-temperature absorption application at the last stage of separation for the considered raw gas composition provides an output of the target C3+ fraction approximately two times greater in a wide range of pressures and temperatures compared to the low-temperature separation. The possibility of increasing the degree of the C3+ fraction extraction into commercial unstable condensate at the last stage of separation in the low-temperature absorption by 21 % is justified only by optimizing the operating parameters of the unit without changing the technological scheme. At the raw gas flow rate of 225 m3/hour the C3+ fraction extraction into unstable commercial condensate increases to 6,6 g/m3 of raw gas without modernization of the technological scheme of the unit, and this is an additional over 35 MT/day C3+ fraction with a corresponding reduction in its entrainment with the product gas, by optimization of low-temperature absorption thermobaric parameters (change of pressure from 3,75 to 5,0 MPa and temperature from minus 30 to minus 35 °C). When «weighting» the component composition of the absorbent by reducing the pressure in the unstable condensate separator of the first stage separation the degree of extraction of C3+ fraction in the product unstable condensate in the low-temperature absorber increases by 25 %, i. e. 6,6 g/m3, and this is 7 MT/day in addition with a corresponding further reduction of its content in the product gas. However, the implementation of such a regime already requires minimal modernization of the low-temperature absorption unit by inserting a pump into the process pipeline for supplying unstable irrigation condensate from the R-1 separator to a low-temperature absorber, which is repaid in a short time.

Keywords

• gas and condensate field
• gas field treatment
• low-temperature absorption
• computer simulation
• temperature and pressure conditions
• separation gas
• unstable condensate output
• selective absorbent
• pump