The word “annulus” is correct and can be used in written English.
It is used to describe a ring-shaped structure or a figure with a hollow center. An example sentence would be: “The annulus of Saturn is visible from Earth with the help of a telescope.”.
It is not clear how much oil there is in the annulus, or how it might or might not be able to get from the annulus into the production casing.From what BP is saying it seems likely that its surface cementing will put a solid plug into the production casing, but quite possibly not into the annulus, which means there might be a way for the wolf to wiggle out.
It will be end[ed] with the relief wells being drilled, and the annulus and the casing being filled with mud and cement being poured".
In a properly-functioning well all the fluids involved, be they mud going down or oil coming up, should be inside the production casing while the space between the casing and the outside of the well (the annulus) is sealed off.
This is one of the reasons that the relief well is still going ahead: it will pierce the annulus and allow the engineers to flush it with mud and close it definitively with more cement.
Not only are they sparsely cratered, compared with the interior plains of Caloris, indicating a protracted period of plains formation in the annulus, but they show other traits more clearly associated with volcanism than could be seen on Mariner 10 images.
The origin of these plains, which form a broad annulus surrounding the basin, has been controversial.
Usually, the gas is injected down the annulus between the casing and production tubing and through a special valve at the bottom of the tubing.
Available evidence suggests that in a strong tornado, most of the rising air surges upward in a cylindrical annulus around the central axis.
A longitudinal groove, the sulcus, extends from the annulus posteriorly to the point at which a second flagellum is attached.
A return to the original bottom-blown Bessemer concept was developed in Canada and Germany in the mid-1960s; this process used two concentric tuyeres with a hydrocarbon gas in the outer annulus and oxygen in the centre.
