Survey information shows annular gas flow associated with cementing defects to be a major problem in shallow casing strings offshore as well as in other cemented strings in oil and gas wells. The gas flow hazard to safety, environment, and economics could be reduced by an aggressive program keyed to prevent gas migration. The program components are: (1) historical data base; (2) training; (3) research of cement hydration in a long, thin column; and (4) development of logging-surveillance devices.