Abstract: There is disclosed apparatus for use in completing a well whose well bore has a substantially horizontally extending lower end into which a casing string is to be lowered, the apparatus including a tool adapted to be connected in the casing string and having a plug therein above a back pressure valve installed in the lower end of the string to form a buoyant chamber within the casing string which is filled with a low density fluid for lowering into the substantially horizontally extending lower end of the well bore.

Abstract: There is disclosed a casing centralizer which comprises a pair of longitudinally spaced collars adapted to be assembled about the casing, and bow springs which extend longitudinally between the collars. The ends of the bow springs are secured to the collars by means of outwardly bent portions at the ends of the bow springs which are adapted to fit within openings in the collars, and a tab on one side of each collar opening which extends inwardly from the inner surface of the collar and passes through an opening in the end of the bow spring adjacent its outwardly bent portion, whereby each tab may be bent over the inner surface of the bent portion at the end of the bow spring so as to hold the outer surface of the end of the bow spring against the inner surface of the collar.

Abstract: An auto-fill flow valve for use in providing valving action in a conduit, the valve having a releasable locking mechanism which prevents the valving element from moving to seat against the valve seat until the locking mechanism is released. Also provided is a valve guide for receiving the releasable locking mechanism and holding it against the valving element.