Unlike drilling, in WO situation you have the well cased and perforated. In most cases, you have one formation to work with one pressure gradient. If the well is killed and static you will not have gas migration uphole.
If you have losses into formation, then you have to take action. Depending on well configuration and the objective of WO, this might include use of LCM, temporarily isolating the zone with plug, cementing, or in some severe cases working with total losses (you give the well whatever it can drink to maintain the fluid column).