This document is a project report submitted by students to Reliance Industries Limited on developing techniques for subsea flow measurement in deepwater fields. It evaluates using blockage factor and virtual metering to detect blockages in subsea pipelines and estimate water-gas ratio trends. Blockage factor relates the excess pressure drop across a pipeline blockage to the blockage size. Virtual metering determines well flow rates using existing well instrumentation when direct meters are absent. The techniques were tested on the KG D6 gas and oil fields offshore India and can help optimize production and reservoir monitoring in deepwater fields.