Dual piston, single phase sampling mechanism and procedure

A method for maintaining a phase integrity of a deep well formation sample comprising:

• dividing a cylinder into at least three, variable volume chambers including an intermediate chamber and first and second end chambers;
• charging said intermediate chamber with high pressure gas;
• providing substantially free transfer of wellbore fluid into and from said first end chamber;
• and
• channeling a formation fluid flow into said second end chamber.

An apparatus for sampling a formation fluid, comprising:

• a fluid receiving vessel;
• a first piston in the vessel associated with a first end chamber;
• a second piston in the chamber associated with a second end chamber;
• a first conduit configured to provide uncontrolled fluid communication between a wellbore annulus and the first end chamber;
• an intermediate chamber formed in the vessel by the first piston and the second piston;
• a high pressure gas in the intermediate chamber;
• and
• a pump configured to pump the formation fluid into the second end chamber, wherein the pump is configured to compress the intermediate chamber by pumping the formation fluid into the second end chamber.

An apparatus for sampling a formation fluid, comprising:

• a fluid receiving vessel;
• a first piston in the vessel associated with a first end chamber;
• a second piston in the chamber associated with a second end chamber;
• a first conduit configured to provide uncontrolled fluid communication between a wellbore annulus and the first end chamber;
• an intermediate chamber formed in the vessel by the first piston and the second piston;
• a high pressure gas in the intermediate chamber;
• and
• a pump configured to pump the formation fluid into the second end chamber, wherein the pump is configured to displace a wellbore fluid from the first end chamber by pumping the formation fluid into the second end chamber.