After the well is drilled, it can produce hydrocarbons anywhere from 5 to 50 years.
The type of the well, formation, completion as well as maintenance affect the lifespan of the well.
At some point comes a time when production rates become uneconomical and expenses for keeping the well operational become higher than what the owners get from sales of hydrocarbons.
The revenue from the sale of hydrocarbons highly depends on the oil prices and when the prices drop and stay low for long periods of time many wells can become uneconomical.
Another issue with older wells is that water cuts often increase with time and wells start to produce more water than hydrocarbons.
So when the wells stop making money for the owners they are usually abandoned or converted into injection wells.
Related: What Is Enhanced Oil Recovery?
How the Oil and Gas Wells are Abandoned?
Usually to abandon the well it needs to be plugged so that formation fluids cannot get to the surface or into groundwaters.
Often cement plugs are used for that.
After the well is plugged with cement, a wellhead portion of the well is removed, and the area around the well is reclaimed by removing any dirty soil and planting new vegetation.
The goal is to leave the spot where the well is located in a similar condition as it was before this well was drilled.
However as with anything else if the poor quality job was done during well abandonment to save money there is a potential for well fluid to eventually escape and cause damage.
Related: What is Cementing in Oil and Gas?
What is Temporary Well Abandonment?
In some cases where the company might want to reactivate the well in the future, temporary abandonments are used.
Temporary abandonments are similar to permanent ones but the wellhead is usually left intact and cement plugs are smaller.
When the well needs to be brought back on production, cement plugs can be milled out with coiled tubing to open the wellbore and allow the well fluid to flow.
What are the Orphan Wells?
There are situations when the oil company owning the well goes bankrupt and the wells are left without their owner.
These wells left by the oil and gas companies are called orphan wells.
In cases like that often government agencies have to intervene and properly abandon them.
In some countries and states the oil and gas companies are required to pay a certain amount of money upfront when the well is drilled which is later used to abandon the well.
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