Metal pad for downhole formation testing

This invention relates to downhole tools used to acquire and test a sample of fluid from a formation. More particularly, this invention relates to a sealing arrangement that creates a seal between a sample probe and a formation in order to isolate the probe from wellbore fluids. Methods and apparatus for isolator pad assemblies used in formation testing equipment. The pad comprises a primarily metallic pad member and a retractable resilient sealing member. The resilient sealing member is maintained in a retracted, protected position until extended to seal against the wellbore. When extended the metallic pad pushes into the mudcake until a raised ring of material on the surface of the pad contacts the formation. Once the pad is in place, the resilient sealing member, which is molded to an extending metal sleeve, is extended and contacts the mudcake to form a primary seal. With the primary and secondary seals energized, a fluid sample can be collected from the formation without contamination from wellbore fluids.