Drill stem testing apparatus

Claim 1

IN A STRING OF TOOLS FOR TESTING A WELL BORE INCLUDING A TEST VALVE FOR SELECTIVELY PERMITTING THE FLOW OF FORMATION FLUID INTO THE INTERIOR OF SAID STRING OF TOOLS, THE COMBINATION OF MEANS FOR SELECTIVELY MAINTAINING SUCH FORMATION FLUIDS ENCLOSED IN SAID STRING OF TOOLS, WHICH MEANS COMPRISES: MEANS FORMING A FIRST CHAMBER IN THE STRING OF TOOLS, INCLUDING VALVE MEANS AT ITS UPPER END, THE UPPER END OF SAID FIRST CHAMBER AND ASSOCIATED VALVE MEANS BEING ARRANGED TO BE POSITIONED BELOW THE UPPER END OF THE WALL BORE WHEN THE STRING OF TOOLS IS IN POSITION FOR TESTING THE WELL BORE; MEANS FORMING A SECOND CHAMBER IN THE STRING OF ROOLS, INCLUDING VALVE MEANS AT ITS LOWER END; VALVE MEANS POSITION INTERMEDIATE OF SAID FIRST AND SECOND CHAMBER, EACH OF SAID VALVE MEANS HAVING CONTROL PORTIONS EXPOSED TO THE EXTERIOR OF SAID STRING OF TOOLS; SELECTIVELY OPERABLE REVERSING VALVE MEANS IN SAID FIRST CHAMBER, AND MEANS OPERABLE FROM THE EXTERIOR OF SAID STRING OF TOOLS FOR SELECTIVELY OPERATING SAID LATTER VALVE MEANS.