For non-vanilla blocks to be generated the mods need to be installed and working at world generation. So, if for example you were to take a vanilla world and pop it into a tekkit server none of the above would have been generated in chunks that already exist but would pop up in newly generated chunks. If you arent getting any errors on server startup try going into creative, fly over somewhere you haven't been before to generate fresh chunks and seeing if there are any oil wells kicking around.