Final answer:
Workover rigs are the specific units designed to conduct workovers on 'killed' wells in the petroleum engineering field, where safety and control of well pressures are critical.
Step-by-step explanation:
The question "Which specific unit is designed for conducting workovers that are killed?" relates to a specialized area of engineering, specifically within the discipline of petroleum engineering. In the context of this discipline, a 'killed' well is one where control has been gained over unexpected high pressures by replacing the reservoir fluids with a heavier, more controlled fluid typically called 'kill fluid.' The specific units designed for conducting workovers on these 'killed' wells are known as workover rigs. Workover rigs are equipped to handle the complexity and safety concerns associated with maintaining well control and performing remedial work on wells that have been 'killed.' For such procedures, safety is of the utmost importance, hence specialized equipment and protocols are in place to ensure operations are conducted without incidents.