Method and apparatus for installing a well

A well installation preform for locating and dispensing granular materials into a bore hole around the screen of a well casing comprising:

• a cylindrical sleeve member adapted to be removable located about the casing adjacent the screen for insertion into the borehole with the casing;
• A closure member for the sleeve having one end arranged to be held secured to the casing adjacent the screen and being separable from the sleeve;
• a flexible liner arranged along an inner wall of said sleeve, said liner having one end wrapped around the end of the sleeve adjacent the closure and attached to an outer surface of said sleeve, and its other end secured for relative movement with respect to the sleeve, said sleeve and liner defining an annular space about said casing for containing the granular materials therein, said granular materials disposed in said annular space in a multilayered arrangement comprising a layer of filter material extending from the closure in a sufficient amount to bridge the screen, a layer of capping or sealing material adjacent to the filter material above the screen and a layer of filler material adjacent the capping material;
• and
• means for separating the sleeve from the closure and for extracting the cylindrical member from the bore hole and everting the sleeve such that the granular material is uniformly dispensed from the annular space in the preform to between the casing and borehole and is maintained in said multilayered arrangement by the everting action of said liner in accordance with extraction of said sleeve, said layered arrangement for establishing an isolated filtration zone in the borehole about the screen said filtration zone being isolated by said capping material.