  We perform 2-dimensional relativistic hydrodynamical simulations in the
context of collapsar model. Calculations of explosive nucleosynthesis are also
accomplished. We investigate the influence of the structure of the progenitor
and energy deposition rate on the resulting explosive nucleosynthesis, assuming
that 56Ni is mainly synthesized in the jet launched by the neutrino heating. We
show the amount of 56Ni is very sensitive to the energy deposition rate. Thus
we conclude that it is quite natural not to detect an underlying supernova in
some X-ray afterglows as in GRB 010921. We also point out the possibility that
the relative abundance of the elements with intermediate mass number such as Si
and S in the X-ray afterglow of GRB 011211 may be naturally explained if the
energy deposition rate at the central engine is relatively long because little
amount of 56Ni should be synthesized under such an environment. If this
discussion is true, there should be correlation between the line features in
the X-ray afterglow and duration of the GRB. It should be noted that the
duration of GRB 011211 is 270 seconds, making it the longest burst ever
observed by Beppo-SAX although it suffers from the effect of red-shift
(z_host=2.14), which supports our conclusion. Our results also suggest that the
type I collapsar model in which the energy deposition rate is relatively low
(\dot{E} \sim 10^{51} erg/s) might have difficulty in reproducing the observed
amount of 56Ni in a hypernova such as SN 1998bw. This means that the mechanism
of the central engine of a hypernova accompanying GRB may be constrained by the
discussion of explosive nucleosynthesis.
