[HiTech RedNeck]

This assumes the pressure in the oil pocket never changes and can be exactly matched with mud pressure due to mud weight. If there’s a little too much mud, and/or something decreases the pressure of the oil in the pocket (geothermal variation?) the mud-oil interface would go sliding down the shaft.

[screaminsunshine]

Right you must adjust the amount of mud as it equalizes in the hole. It does it on its ownThen you put the cement .

[Wonder Warthog]

"This assumes the pressure in the oil pocket never changes and can be exactly matched with mud pressure due to mud weight. If there’s a little too much mud, and/or something decreases the pressure of the oil in the pocket (geothermal variation?) the mud-oil interface would go sliding down the shaft."

Since this is a procedure routinely used in virtually all oil wells, I think we can assume that the guys who formulate the "mud" know how to handle it, even if we don't.

And we already know from measurements taken after the BOP was successfully shut in with the pressure cap that the reservoir pressure is remaining very constant.