Blow-outs happen very infrequently nowadays, thanks to strict well-control procedures and improved drilling equipment. When they do occur, control over the well can usually be regained rapidly after capping. In certain cases, it may be necessary to kill the well after a blow-out by injecting kill fluid through a relief well. The simulator described in this report predicts the sequence of events during such operations. Study of the sensitivity of simulation results to variation of input parameters provides a basis for optimal design of relief wells and optimal choice of kill procedures.