Mid-Scale FLNG Production Unit for Marginal Fields

Abstract

The scale and productive life of associated gas from subsalt production and small offshore gas reservoirs in remote areas, has made economic justification difficult for dedicated onshore processing facilities with associated subsea pipelines. Floating LNG (FLNG) offer freedom from the subsea pipeline, but the biggest have been designed for specific large fields. Another approach is to build flexibility into the design of the FLNG facility, potentially increasing the initial CAPEX of the unit, instead of targeting a specific field. This approach allows the CAPEX to be amortized across multiple offshore fields, avoiding a stranded investment. This paper addresses topsides where flexibility in topsides processing units is advantageous for pursuit of multiple marginal fields over the life of the FLNG asset, focusing on the 4.5 to 9 MSm3/day (160 to 330 MMSCFD) of natural gas liquefied to 1 to 2 million tonnes per annum of LNG. Standardizing modular designs for FLNG processing units, provides opportunities to build or retrofit the FLNG facility in smaller yards and can reduce project schedule and costs associated with the design and construction of the FLNG facility. Considering future relocation of the floating unit to other fields, requires some flexibility in the initial design to reduce future changes, without negatively impacting first field performance. Using this approach, producing gas from marginal offshore fields could be a viable option by utilizing small or mid-scale FLNG to liquefy gas, using one facility to liquefy serially multiple marginal fields.