Annulus pressure operated downhole choke and associated methods

Abstract

A downhole choke and associated methods provide enhanced efficiency and accuracy in well sampling and testing operations due to its capability for substantially minimizing the amount of time needed to establish steady state flow conditions in a well, and the ability to sample fluids downhole at varying downhole flow restrictions. In a described embodiment, a downhole choke is operable to restrict fluid flow therethrough by applying a predetermined fluid pressure to an annulus formed between the choke and the wellbore. The downhole choke has an axial flow passage formed therethrough, a portion of which has interchangeable flow areas. The flow areas are interchanged upon application of the predetermined fluid pressure, and again interchanged upon expiration of a time delay. One of the flow areas permits substantially unrestricted fluid flow therethrough, and another of the flow areas permits restricted flow therethrough.

Dependencies are inferred from the claim text.