in fig1 is inserted into bore hole 3 drill string tester 1 has upper inflate packer 7 and lower inflate packer 8 disposed about zone 5 the zone which is being tested recorder carrier 9 and spacer 10 are located between upper inflate packer 7 and lower inflate packer 8 recorder carrier 9 is used to carry the instruments which record the data from the tests carried out when fluid is forced into the formation through formation flow ports 11 release device 13 is fitted above upper inflate packer 7 and is in fluid connection with upper inflate packer 7 release device 13 is also in fluid connection with lower inflate packer 8 by means of annular conduit 12 in space 10 around conduit 16 conduit 16 is the central bore through which the formation flows to the surface during the testing procedure located above release system 13 are suction screen 18 and inflate pump 19 drag spring 20 below lower inflate packer 8 engages the wall of well bore 3 and prevents the system from turning as drill stem tester 1 is rotated release system 13 is depicted in detail in fig2 release system 13 includes upper adaptor 30 flow mandrel 40 cylinder 50 piston 60 and lower adaptor 100 the upper adaptor flow mandrel and cylinder together form the first element or upper element of the invention in this embodiment lower adapter 100 is the second element and.