Subsea test adaptor for calibration of subsea multi-phase flow meter during initial clean-up and test and methods of using same

A riser assembly comprising:

• an emergency disconnect package, the emergency disconnect package comprising an emergency disconnect package production bore and an emergency disconnect package annulus bore and includes a production bore isolation valve and an annulus bore isolation valve;
• a lower riser package, the lower riser package comprising a lower riser package production bore and a lower riser package annulus bore and includes a first and a second production bore isolation valve, a first and a second annulus bore isolation valve, and a cross-over valve disposed between the first and second production bore isolation valves and between the first and second annulus bore isolation valves, the lower riser package production bore being in fluid communication with the emergency disconnect package production bore and the lower riser package annulus bore being in fluid communication with the emergency disconnect package annulus bore;
• an adapter for securing on a vertical subsea Christmas tree having a production wing valve, the adapter comprising a flow loop and an adapter production bore and an adapter annulus bore, the adapter production bore being in fluid communication with the lower riser package production bore and the adapter annulus bore being in fluid communication with the lower riser package annulus bore,
• wherein, the flow loop is in fluid communication with the adapter production bore and releasably connectable to a production line and the production wing valve of the vertical subsea Christmas tree, with a multi-phase flow meter in fluid communication with the production wing valve and the flow loop, to verify operation and calibration of the multi-phase flow meter with a fluid from the production wing valve.