I have used the repair kit from these guys. Similar damage but to non-driveside chainstay, bike is still going strong 3 years later.
http://www.carbonology.com/repair-moulding-kits-c-130.html?sesid=hn4jh7r0mm4cvldiivflqquaa6%5D
I cut a triangular piece of carbon big enough to go round the chainstay 4 or 5 times. Start wrapping the narrow end round the break, wetting with resin each wrap and covering more of the chainstay, this spreads the stresses. Finally, wrap cling film tightly around the repair to try and squeeze any air out. Once dry remove the clingfilm. You can leave as is, or sand to produce a smooth surface, I didn’t bother becasuse it was going to be covered by chaninstay protection tape anyway.