Transporting oil and gas mixture in gathering system at White Tiger oil field

摘要

Transport of oil and gas from producing wells to separationunits in two-phase flow by one pipeline could significantlyreduce the budget for building the product gathering system.However, practice and studies showed that it would beeffective only if the gas flow rate ratio β≤ 0.7.JV Vietsovpetro crude oil, mainly being produced from thebasement of southern part of the White Tiger field, istransported in form of two-phase flow from Satellite Platforms(SP) to Central Processing Platform (CPP) for gas separationthrough submarine pipeline (without thermal insulation). Thecrude has high wax content (up to 27% by weight), high pourpoint temperature 33-34℃, and average GOR of 166 m~3/m~3 @20℃ & 100 kPa(a). The transport and gas separation processesencountered many difficulties due to pressure and flow ratefluctuations. Increasing pressure in the pipelines to 2200-2500kPa(g) improved the situation, but not enough. A consequencewas also that the well flow rates were decreased.This paper describes the results from a full-scale field teston transportation of 5848 m3/day (@ 20℃ & 100 kPa(a)) wellproduct from SP to CPP as an oil and gas mixture. Studieswere carried out on subsea un-insulated pipeline with OD0.324m and length around 2000m, with gas flow rate ratios,varying from 0.623 to 0.868. Developed on the above basis thetechnology of preliminary gas separation on the SP and thentransport of the gas and oil by two separate pipelines hasassisted JV Vietsovpetro in elimination of a/m difficulties.Application of this technology would gain significant benefitswhen most of the wells on the SP moved to gaslift production.