Abstract: A service tool string (34) is releasably attached to a bottom hole assembly (18) and forms a production string as well as a work string. The tool (35) has a mandrel (102) and a slide valve assembly (68) mounted on the mandrel for relative sliding movement. Crossover ports (114, 124) are provided in the mandrel (102) and the slide valve assembly (68). Slide valve assembly (68) moves by gravity and spring action when not contacted by the bottom hole assembly (18) to a position in which ports (114, 124) are blocked as shown in FIG. 7B. Upon contact of slidable valve assembly (68) with the bottom hole assembly (18), slide valve assembly is moved upwardly for alignment of ports (114, 124) as shown in FIGS. 5B and 6B. An equalizing valve (29) as shown in FIGS. 10-12 is effective to equalize the fluid pressure within the bottom hole assembly (18) with the fluid pressure outside the perforated casing section (23) so that in a reverse position as shown in FIG.