Abstract: The present invention provides improved primary well cementing methods and apparatus. The methods basically comprise the steps of releasing a displacement plug into the casing to be cemented and pumping a first displacement fluid behind the displacement plug while measuring the quantity of the first displacement fluid required to land the displacement plug on a float collar or the like connected near the bottom of the casing, releasing a bottom cementing plug into the casing and pumping a cement slurry behind the bottom cementing plug in a predetermined quantity and then releasing a top cementing plug into the casing and pumping a second displacement fluid behind the top cementing plug in a quantity substantially equal to the measured quantity of the first displacement fluid thereby ensuring that the cement slurry is not under or over displaced in the annulus between the casing and the well bore.

Abstract: A cased suspended sub-sea well is secured for abandonment by setting a packer in the casing thereof, the packer having a perforating gun suspended therefrom firing the gun to perforate the casing and then injecting cement into the annulus behind the casing.