Depending on the type formation involved, production can cause the presure to drop to a point the wellbore loads with liquids (oil or water) and can no longer produce naturally. Based on the age of the well you’re talking about gas lift valves may have been installed so that some, or all, of the gas production is reinjected to raise the pressure enough to lift the liquids.
Once loading starts it can be a chronic problem that take a range of alternatives to manage. Soaping, by dropping soap sticks down the wellbore, doesn’t require power. It may only be a short term fix but if the soap can turn enough of the liquids into foam that is lighter to lift then production can get going again.