beyond the casing 21 in order to allow for side track drilling at different depths the surface is indicated at s the rock at r a drill string is shown at 52 fig9 shows the application of a smaller drill 51 u2032 and drill string 52 u2032 during drilling of one of the lower production holes 34 the larger drill 51 and drill string 52 shown in fig8 have been retracted a whip stock 29 u2032 and anchor 6 u2032 has been placed in the lowermost part of the return hole to allow sidetracking at different positions in the figure it is shown that the drill 51 u2032 can be guided to the side and downwards by the geometry of the whip stock a casing is shown at pos 21 fig1 shows the drill 51 u2032 and drill string 52 u2032 during drilling one of the upper holes 34 u2032 the drill and string and also the whip stock shown in fig9 have been retracted following this a whip stock 29 that represent an assembly with a larger vertical extension than that shown in fig9 is installed this allows sidetrack drilling at a given vertical position by this arrangement an uppermost hole 34 u2032 can be drilled towards a lowermost hole 34 using one of several existing techniques for guided drilling a completed circulation path or production hole u2018 p u2019 is shown with an upper hole 33 u2032 and a lower hole 33 at the connection point 11 local fracturing.