'nears completion' is correct and usable in written English.
You can use it when something is nearing completion, such as a task, process, etc. For example: The new school building project nears completion.
Princeton's new Lewis Science Library nears completion.
30 May 2011: The police investigation nears completion.
The price will rise as the house nears completion.
The second stage comes as the dissertation nears completion.
Even as the project nears completion, the future of solar thermal power plants is in doubt.
The building blocks slip into place as a Chinese filmmaker's grand opera nears completion.
As the vessel nears completion a number of tests are made.
Today, the land that Mavee once owned costs six times that sale price, as the arterial highway nears completion.
But history shows that the power of an infrastructural technology to transform industries always diminishes as its buildout nears completion.
He declined to note which ones, saying they are to be announced in tranches as the project nears completion.
The north side is not likely to open for at least two years, as 3 World Trade Center nears completion.
