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The present invention provides a cementing system and method for wellbores by cementing an annulus between a wellbore casing and a wellbore. In at least one embodiment, the invention includes a landing collar defining a restricted passage, a wellbore casing defining a passage coupled to the landing

The present invention provides a cementing system and method for wellbores by cementing an annulus between a wellbore casing and a wellbore. In at least one embodiment, the invention includes a landing collar defining a restricted passage, a wellbore casing defining a passage coupled to the landing collar, a top cementing plug for sealingly engaging the wellbore casing, a bottom cementing plug for sealingly engaging the wellbore casing, and a fluid injection assembly coupled to the wellbore casing for injecting fluidic materials into the wellbore casing and controllably releasing the top cementing plug and the bottom cementing plug into the wellbore casing. The bottom cementing plug includes a plug body defining a plug passage, a frangible membrane for sealing the plug passage, and a one-way valve for controlling the flow of fluidic materials through the plug passage. The invention also includes the bottom cementing plug and methods for operation.

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1. An apparatus for cementing an annulus between a wellbore casing and a wellbore, comprising:a landing collar defining a restricted passage;a wellbore casing defining a passage coupled to the landing collar;a top cementing plug for sealingly engaging the wellbore casing;a bottom cementing plug for

1. An apparatus for cementing an annulus between a wellbore casing and a wellbore, comprising:a landing collar defining a restricted passage;a wellbore casing defining a passage coupled to the landing collar;a top cementing plug for sealingly engaging the wellbore casing;a bottom cementing plug for sealingly engaging the wellbore casing comprising:a plug body defining a plug passage;a frangible membrane for sealing the plug passage; anda one-way valve adapted to control the back flow of fluidic materials through the plug passage; anda fluid injection assembly coupled to the wellbore casing for injecting fluidic materials into the wellbore casing and controllably releasing the top cementing plug and the bottom cementing plug into the wellbore casing. 2. The apparatus of claim 1, wherein the one-way valve comprises:a flapper valve. 3. The apparatus of claim 1, wherein the one-way valve comprises:a ball valve. 4. The apparatus of claim 1, wherein the one-way valve comprises:a spring biased dart valve. 5. A method of cementing an annulus between a wellbore casing and a wellbore, comprising:positioning a wellbore casing defining a passage and including a landing collar at one end defining a restricted passage into the wellbore;injecting a non-hardenable fluidic material into the other end of the wellbore casing;injecting a bottom cementing plug into the other end of the wellbore casing, the bottom cementing plug comprising:a plug body defining a plug passage;a frangible membrane for sealing the plug passage; anda one-way valve adapted to control the back flow of fluidic materials through the plug passage;injecting a hardenable fluidic sealing material into the other end of the wellbore casing;injecting a top cementing plug into the other end of the wellbore casing;injecting a non-hardenable fluidic material into the other end of the wellbore casing;breaking the frangible membrane of the bottom cementing plug to permit the hardenable fluidic sealing material to pass through the plug passage, the one-way valve, and the restricted passage into the annulus between the tubular member and the wellbore; andthe one-way valve preventing the hardenable fluidic sealing material from passing from the annulus back into the wellbore casing. 6. The method of claim 5, wherein the one-way valve comprises:a flapper valve. 7. The method of claim 5, wherein the one-way valve comprises:a ball valve. 8. The method of claim 5, wherein the one-way valve comprises:a spring biased dart valve. 9. A system for cementing an annulus between a wellbore casing and a wellbore, comprising:means for positioning the wellbore casing into the wellbore;means for injecting a non-hardenable fluidic material into the wellbore casing;means for injecting a hardenable fluidic sealing material into the wellbore casing;means far separating the non-hardenable fiddle material and the hardenable fluidic scaling material within the wellbore casing;means for pressurizing the hardenable fluidic sealing material within the wellbore casing;means for controllably releasing the hardenable fluidic sealing material into the annulus between to wellbore casing and the wellbore; andmeans for preventing the hardenable fluidic sealing material from flowing from the annulus into the wellbore casing. 10. A bottom cementing plug for use in a system for cementing an annulus between a wellbore casing and a wellbore, comprising:a plug body defining a plug passage;a sealing element coupled to the plug body for sealingly engaging the wellbore casing;a frangible membrane for sealing the plug passage; anda one-way valve adapted to control the back flow of fluidic materials through the plug passage. 11. The bottom cementing plug of claim 10, wherein the one-way valve comprises:a flapper valve. 12. The bottom cementing plug of claim 10, wherein the one-way valve comprises:a ball valve. 13. The bottom cementing plug of claim 10, wherein the one-way valve comprises:a spring biased dart valve. 14. A system f or cementing an annulus between a tubular liner and a wellbore, comprising:means for injecting a non-hardenable fluidic material into the tabular liner;means for injecting a hardenable fluidic sealing material into the tubular liner;means for separating the non-hardenable fluidic material and the hardenable fluidic sealing material within to tubular liner;means for pressurizing the hardenable fluidic sealing material within the tubular liner;means for controllably releasing the hardenable fluidic scaling material into the annulus between the tubular inner and the wellbore; andmeans for preventing the hardenable fluidic sealing material from flowing from to annulus into the tubular liner. 15. The system of claim 14, further comprising:means for coupling the tubular liner to the preexisting wellbore casing.