How do you design a custody transfer metering system for oil and gas?

Custody transfer metering requires highest accuracy for fiscal measurement. Design elements: meter selection (Coriolis, ultrasonic, turbine for liquid; ultrasonic for gas) with accuracy <0.15%, prover system (pipe prover, compact prover) for in-situ calibration, flow conditioning (straightening vanes, flow conditioners), temperature and pressure compensation (API 11.1 tables), sampling system for quality measurement (density, water cut, sulfur), data acquisition system (flow computer with audit trail), redundancy (duty/standby meters), and compliance with API MPMS, AGA, and contractual requirements. Implement measurement uncertainty analysis and regular proving schedules.