| 摘要 |
A method and apparatus for indicating the position of a cement wiper plug in a wellbore during liner or casing cementing operations. The arrival of the cement wiper plug at a shearable, temporary restriction means in a pipe string is sensed by an increase in pipe string pressure at the surface. Using the knowledge of the location of this shearable, temporary restriction means, a determination of whether or not it is desirable to displace the cement wiper plug to a landing assembly at the bottom of the pipe string can be made. A predetermined amount of displacing fluid, sufficient to either completely or partially displace the cement wiper plug to the landing assembly, can then be introduced into the pipe string. The apparatus includes a section of pipe string with an interior shearable, temporary restricting means to restrict the motion of the cement wiper plug through the section of pipe string, and a casing string wiper plug, for those casing string cementing operations where at least one casing string wiper plug may be required, designed to pass the interior shearable, temporary restricting means without shearing it from the interior of the section of pipe string.
|
