Isolation washpipe for earth well completions and method for use in gravel packing a well

A method of isolating a production zone and subsequently placing the isolated zone on production comprising the steps of:

• running and setting first and second wellpackers each having a smooth seal bore therein above and below the production zone;
• running a production string including at least one well production screen and having seal bore subs attached to each end thereof and having a sufficient number of sections of threadedly interconnected blank pipe to space the first packer and the second packer above and below the production zone threadedly connected to one end of the well screen, the uppermost of said sections of blank pipe having releasable latching means attached thereof;
• placing a gravel pack assembly including a crossover service tool and a sleeve valve shifting tool within the flow bore of the second well bore packer, and well bore packer having a wash pipe releasably engaged with the gravel pack assembly by shearable means and depending thereform, the wash pipe having sealing means and releasable latching means mounted thereon;
• simultaneously running the gravel pack assembly, the well bore packer and the wash pipe into the hole;
• gravel packing the well bore;
• manipulating the gravel pack assembly to seal the washpipe into said first packer and to latch the wash pipe into sealing engagement therewith;
• removing the gravel pack assembly from within the bore of the production string leaving the wash pipe in sealing engagement with said first packer and the second packer;
• and,
• establishing communication between the flow bore of the wash pipe and the producing zone.