초록 ▼

A method for controlling a fluid pressure applied to a cementing plug comprises disposing the cementing plug within a casing string to define a trapped volume of fluid within the casing string, isolating a portion of the trapped volume of fluid adjacent the cementing plug to define an isolated volum

A method for controlling a fluid pressure applied to a cementing plug comprises disposing the cementing plug within a casing string to define a trapped volume of fluid within the casing string, isolating a portion of the trapped volume of fluid adjacent the cementing plug to define an isolated volume of fluid, and relieving the fluid pressure within the isolated volume of fluid at a first rate sufficient to prevent damage to or inadvertent release of the cementing plug. An apparatus for relieving fluid pressure within a casing string being run into a well bore comprises at least one equalizer valve connected to a work string extending into the casing string, and a sealing device disposed above the equalizer valve to seal an annular space formed between the work string and the casing string.

대표청구항 ▼

We claim: 1. A method for controlling a fluid pressure applied to a cementing plug comprising: disposing the cementing plug within a casing string to define a trapped volume of fluid within the casing string; isolating a portion of the trapped volume of fluid adjacent the cementing plug to define a

We claim: 1. A method for controlling a fluid pressure applied to a cementing plug comprising: disposing the cementing plug within a casing string to define a trapped volume of fluid within the casing string; isolating a portion of the trapped volume of fluid adjacent the cementing plug to define an isolated volume of fluid, wherein the isolating step comprises providing a seal within the casing string above the cementing plug; relieving the fluid pressure within the isolated volume of fluid at a first rate sufficient to prevent damage to or inadvertent release of the cementing plug; and relieving another fluid pressure within the trapped volume of fluid above the seal at a second rate. 2. The method of claim 1 wherein the first rate is independent of the trapped volume of fluid. 3. The method of claim 1 further comprising varying the isolated volume of fluid based on the first rate. 4. The method of claim 1 wherein the trapped volume of fluid is defined by the position of a casing running tool with respect to the cementing plug. 5. The method of claim 1 wherein the isolated volume of fluid is defined by the position of the seal with respect to the cementing plug. 6. The method of claim 1 wherein the first rate is faster than the second rate. 7. A method for controlling a fluid pressure applied to a cementing plug comprising: disposing the cementing plug within a casing string to define a trapped volume of fluid within the casing string; isolating a portion of the trapped volume oil fluid adjacent the cementing plug to define an isolated volume of fluid, wherein the isolating step comprises providing a seal within the casing string above the cementing plug; and relieving the fluid pressure within the isolated volume of fluid at a first rate sufficient to prevent damage to or inadvertent release of the cementing plug, wherein the fluid pressure within the isolated volume of fluid is at least partially relieved through the seal into the trapped volume of fluid above the seal. 8. A method for controlling a fluid pressure applied to a cementing plug comprising: disposing the cementing plug within a casing string; defining a fixed volume of fluid within the casing string above the cementing plug regardless of the casing string size, wherein the defining step comprises providing a seal within the casing string at a distance from the cementing plug; defining a captured volume within the casing string above the seal; and relieving the fluid pressure within the fixed volume of fluid at a rate sufficient to prevent damage to or inadvertent release of the cementing plug. 9. The method of claim 8 further comprising varying the fixed volume based on the rate. 10. The method of claim 8 further comprising relieving another fluid pressure within the captured volume. 11. The method of claim 10 wherein the fluid pressure is isolated from the cementing plug by the seal. 12. The method of claim 8 wherein the fluid pressure within the fixed volume is at least partially relieved through the seal into the captured volume. 13. An apparatus for relieving fluid pressure within a casing string being run into a well bore comprising: at least one equalizer valve connected to a work string extending into the casing string; and a sealing device disposed above the equalizer valve to seal an annular space formed between the work string and the casing string, wherein the at least one equalizer valve comprises a first equalizer valve above the sealing device and a second equalizer valve below the sealing device. 14. The apparatus of claim 13 further comprising at least one cementing plug connected to the work string below the equalizer valve. 15. The apparatus of claim 13 further comprising a casing running tool connected to the upper end of the casing string. 16. The apparatus of claim 13 wherein the casing string comprises a tapered casing string. 17. The apparatus of claim 13 wherein the sealing device comprises a cup type packer. 18. The apparatus of claim 17 wherein a cup on the packer is inverted.