Setting a Balanced Cement Plug
Basic procedure:
- a) Pump water spacer
- b) Pump slurry
- c) Pump water spacer
- d) Displace with mud {either (i) underdisplace or (ii) balanced)
- e) Pull stinger slowly and do not rotate string (will disturb cement)
CALCULATE
- a) Quantity of cement and mixwater required
- b) Thickening time and compressive strength
Prior to withdrawal of stinger determine:
- c) Height of cement column
- d) Height of water spacer ahead of slurry
- e) Volume of water required behind slurry to achieve a balanced condition
- f) Chase volume
CALCULATIONS
The following calculations are for setting a plug in open hole only (i.e. one size of annulus). The water spacer ahead is also considered to be in open hole/tubing stringer annulus (i.e. one size of annulus). If more than one annulus exists then the calculations will have to be adjusted.
(a) Quantity of cement and mixwater required Vc = Cap0H x Length of plug
(b) Thickening time and compressive strength See Halliburton Cementing Tables
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