Method and apparatus for the multiple stage cementing of a casing string in a well

A system for cementing multiple stages within a well, comprising:

• a cementing valve assembly, comprising,
• a housing assembly, said housing assembly defining at least one radial port;
• a first sleeve assembly, said first sleeve assembly slightly retained within said housing for longitudinal movement relative thereto, said sleeve moveable from a first position substantially covering said port to a second position substantially opening said port;
• a second sleeve assembly retained within said housing for longitudinal movement relative thereto, said second sleeve assembly comprising a sealing sleeve and an actuation sleeve, said sealing sleeve releasably coupled to said actuation sleeve, said second sleeve assembly movable from a first position wherein said sealing sleeve is longitudinally above said port, to a second position wherein said sealing sleeve is substantially adjacent to and covering said port;
• said housing defining a generally radially extending engagement surface, and said first sleeve including a tapered wedging surfaces, said surfaces cooperatively configured to establish a wedging engagement between said first sleeve and said housing assembly when said first sleeve is moved to said second position;
• and
• a first plug member selectively engageable with said first sleeve and adapted to block the flow fluid relative to said first sleeve such that the application of pressure above said first sleeve will cause movement of said first sleeve from said first position to said second position.