Tips for the successful placement of cement plugs

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(1) Set the plug on a firm foundation, if one is not available set the plug on an polymer retaining spacer with the same weight as the mud.

(2) Always use a polymer spacer weighted to midway between the mud and the cement slurry. Use a volume of spacer sufficient to give at least a 250 ft separation between the mud and cement.

(3) In order to maximise hole clean up the spacer should leave the stinger at a rate of at least 8 bbls/min. However as the spacer/cement interface approaches the end of the stinger the displacement rate should be slowed so that the cement is displaced at a rate of 2 - 3 bbls/min giving a  annular velocity of < 90 ft /min.

(4) A batch tank should be used to mix cement plugs.

(5) Prior to mixwater make up the drillwater should be tested to ensure that it is free of salt and solids contamination.

(6) Always underdisplace the cement slurry (4-5 bbls at 10,000 ft).

(7) Unless hole stability is a problem use a stinger fitted with a diverter tool.

(8) Good centralisation, rotation, and reciprocation of the stinger will increase the probability of a successful cement plug.

(9) Once the slurry is in place minimise the risk of contamination by pulling the stinger slowly out of the cement (30 ft /min max.).

(10) Pull the stinger well back above the cement before reverse circulating (200 - 300 ft above ttoc)

Comments  

#1 umoh idongesit Akpan 2015-08-26 10:28
just to know more about plug calculation.
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