tubing 29 and one to the annulus space is then established with the workover vessel prior to removing tubing 29 the well ordinarily must be killed during this procedure the well production fluid is replaced with a heavier fluid the operator can kill the well by opening the downhole safety valve and pumping down the recovery string and production tubing 29 the fluid flows out a port at the lower end of the production tubing 29 back up the tubing annulus upper tubing hanger annulus bore 67 and up one of the choke and kill lines after the well is killed the operator can retrieve production tubing 29 with the recovery string by pulling upper tubing hanger 57 then pulling tubing hanger 27 along with tubing 29 after the workover operation tubing 29 and lower tubing hanger 27 are lowered through tree 41 and re installed lower tubing hanger 27 will orient by engagement of key 58 with orientation sleeve 56 fig2 during the installation alternately the operator may remove tree 41 without pulling tubing 29 in this instance preferably another wireline plug not shown will be installed in a grooved profile in lower tubing hanger 27 before removing tree 41 when tree 41 is pulled upward upper tubing hanger 57 and isolation sleeve 77 will be pulled with tree 41 while tubing hanger 27 and tubing 29 remain in place further the.