CARACAS (Reuters) - Venezuela s former Oil Minister Eulogio Del Pino, in video shot before his detention and published on his Twitter account on Thursday, said he had been a  victim  of an  unjustified attack.  Del Pino, an engineer who also used to lead state oil company PDVSA [PDVSA.UL], said he would exercise his right to self-defense but did not elaborate on who ordered his arrest in the early hours of Thursday.  