Abstract: The upper head assembly includes a main body, a retractable body, a support element and a rear element. A fluid control means is provided for increasing the passage of fluid during the descent into the well are disposed on the main body and comprise a closure/opening body that selectively permits fluid to pass through a bypass chamber inside the main body, in a working position, or through an area of rapid descent that facilitates the passage by following a path, during descent. The fluid bypass chamber is formed by a central chamber with inlet ports and outlet ports that allow a connection of fluid between the central chamber and the outside of the main body. The closure/opening body blocks the flow through the area of rapid descent when the working position is reached.