Method and system for sampling multi-phase fluid at a production wellsite

A method of sampling fluid from a production wellsite, the production wellsite having a tubular extending into a subsea unit for producing a fluid therefrom and a port at the wellsite for accessing the fluid, the method comprising:

• establishing fluid communication between an interface and the port;
• establishing fluid communication between a separation circuit and the interface, the separation circuit comprising at least one sample chamber and a pumping unit, the pumping unit comprising a plurality of pumping chambers, the plurality of pumping chambers each having a cylinder with a piston therein defining a fluid cavity and a buffer cavity;
• selectively flowing the fluid between the separation circuit, the interface and the port at a controlled rate by selectively manipulating the buffer fluid between the buffer cavities of the plurality of pumping chambers;
• discharging buffer fluid from a first buffer cavity to an outtake flowline in response to receiving fluid in a first fluid cavity while discharging buffer fluid from a second buffer cavity to the outtake flowline in response to receiving fluid in a second fluid cavity;
• receiving the fluid in the fluid cavity of at least one of the plurality of pumping chambers and allowing separation of the fluid into a plurality of phases therein;
• and
• collecting at least one sample of at least one of the plurality of phases of the fluid in the at least one sample chamber.