Analysis Of The Exxon Figures

It is important to point out that swabbing can occur while running pipe into the hole as shown at points #5 and #11 in the iZ* figure. The W

maximum swab S pressure occurred while lifting the casing to release the slips. Thixotropic gel and the inertial q force of the mud played major roles. ^ Points #5, #7, #9, and #11 occurred

Surge and Swab Pressures o

Swabbing And Surging Pictures
15.0 17.5

Time (seconds)

while breaking the casing non-uniformly and inertial forces played the major role in these swabs. The magnitude of pressures at points #4, #6, #8, #10 were primarily developed by the velocity of the casing and the attendant friction drag.

The time for running the joint of casing which was 44 feet long was 17.5 seconds. This is equivalent to an average running speed of 151 feet/minute. The equivalent pressure surge at point #8 was 4.4 ppg and the equivalent swab at point #11 was 1.8 ppg.

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