Abstract
The case study applies to an Indian offshore production field which consists of 4 unmanned well head platforms (A1, A2, A3 and AB) and a chartered hired FPSO connected via PLEM to the hub platform AB. The producing wells use gas lift supplied from gas compressors located on the FPSO. Liquid produced is evacuated by tankers and excess gas is exported to an adjacent field via a 16" × 46 km pipeline. New discoveries with total oil in-place volume of 75.55 MMt and associated gas with greater than 30% CO2 have posed a challenge to bring into production. The gas compressors on the FPSO were designed to for gas with maximum 12% of CO2 and as the FPSO is a leased asset, the increased CO2 in the feed was considered "a strict no-no". Also, excess gas is exported via and must have less than 6% CO2 to meet the export pipeline specification.
A concept study was done to identify a feasible method to produce the higher CO2 gas without major changes in FPSO handling facilities. In the technology selection: Solvent adsorption, Absorption beds and Membrane system were evaluated for their usage at an unmanned platform. The selection criteria included: required foot-print & weight, moving parts and minimum intervention. The study recommended a membrane system be used.
This project has many firsts for Offshore India such as: Membrane based CO2 removal, a low BTU hot flare for reject stream disposal and Micro-turbines for meeting basic power requirement. All this will be discussed with fabrication pictures and implementation details. Scheduled offshore platform commissioning is in January 2021.
