Abstract: In connection with a method and a tool for preparing a well for the production of hydrocarbons, it is aimed at perforating a casing portion (26) and working surrounding sediment (80) in a channel-forming manner. For this purpose the tool comprises a drilling means for drilling transverse holes through the casing wall when the tool (10), which is arranged to be raised/lowered and rotated about its longitudinal axis, shared by the casing (26), is placed in a fixed position within the well, through which transverse hole (40) and into surrounding sediment a jetting hose means (42,42a) is arranged to jet/dig its way in a channel-forming manner. The drilling and jetting hose means also have inactive stand-by positions protectively retracted within the tool housing (10a), from and into which they may successively be pushed forward into active working positions and again be withdrawn, as a channel (44) is completed in the sediment (80).