Given: 10,000' casing in 10.7 ppg mud.
Pump into casing, up annulus:
100' 8.5 ppg mud = 44 psi hydrostatic.
1,550' 12.9 ppg cement = 1,040 psi hydrostatic.
1,500' 15.4 ppg cement = 1,201 psi hydrostatic.
9.1 ppg brine until cement is displaced.
Pump pressure required to displace?
Annulus (remaining):
6,850' 10.7 ppg mud = 3,811 psi hydrostatic.
Total hydrostatic pressure in annulus: 6,096 psi.
Hydrostatic pressure in casing: 9.1 ppg brine = 4,732 psi
Pump pressure required to displace?
6,096 psi - 4,732 psi = 1,364 psi (A).
This is a simple displacement problem. It's common in industry and
textbooks both (good examples are in TS2, TS12, Mian, etc...and if you have a chance to take Wines' class, Bing has the best examples of this problem type I've seen). I
referenced this problem using TS12 but as mentioned there are a dozen just like it. All
you need is the basic hydrostatic equation (0.052(D)MW) and to understand how cement
is generally pumped:
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