Abstract: A bridge plug assembly having a nickel titanium alloy flexible member that can be selectively radially expanded so its outer surface sealingly engages a surrounding tubular. The flexible member can comprise an annular membrane like member having coaxial rings on the opposing ends of the flexible member. The percentage of weight of nickel can range up to about 40 to about 58%, 55% or to about 60%.

Abstract: A bridge plug assembly that can be set in a wellbore tubular using wellbore pressure to form a pressure differential on a piston that actuates sliding members. A resilient member, such as a spring, is compressed from a downhole pressure differential. The bridge plug assembly can be removed by equalizing pressure across the piston and the spring. The spring can expand and re-stow the expanded plug. The plug can be formed from a nickel titanium alloy flexible member that can be selectively radially expanded so its outer surface sealingly engages a surrounding tubular. The percentage of weight of nickel can range up to about 40 to about 58%, 55% or to about 60%.

Abstract: A bridge plug assembly having a mandrel and an annular flexible member that is selectively fashioned into a volute that extends radially outward from the mandrel for isolating a portion of a tubular. In an example, a web member is provided that runs between the flexible member and the mandrel, and exits an end of the flexible member. Pulling the web member inverts an end of the flexible member rolling the sidewall of the flexible member into a volute. In another embodiment, upper and lower series of collars circumscribe the mandrel that when pushed towards one another axially squeeze the flexible member therebetween to outwardly bulge the flexible member into contact with a tubular. Continued force applied to the collars causes the flexible member to roll into a volute.

Abstract: A method for determining depth in a wellbore uses inertial navigation in conjunction with a database having one or more measured parameters correlated with depth. The measured parameter may be the lengths of stands forming a drill string, prior survey data relating to a naturally occurring feature such as formation lithology, or data relating to a human made feature such as collars in a casing string. The downhole processor may use accelerometer measurements to calculate a measured depth of a BHA and access the database to retrieve a predicted depth that corresponds with one or more sensor measurements (e.g., motion indicating the addition of a stand to a drill string). Thereafter, if the downhole processor determines that the predicted depth is in agreement with the calculated depth, the processor stores the predicted depth and/or associates the predicted depth with directional surveys taken along the wellbore.