736 



Subsurface Geologic Methods 



closed-in pressure valve and above the packer assembly. This unit permits 

 the free flow of fluids through the packer, as well as around the outside of 

 the packer element while it is run into the well. It equalizes the hydro- 

 static pressure above and below the packer after the test has been com- 

 pleted. Releasing of the mud weight above the packer permits the removal 

 of the packer from the seat without lifting the weight of the column of 

 mud retained in the annulus, leaving only the friction hold of the packer 

 against the wall to be broken loose. This tool also reduces swabbing 

 effect when it is brought out of the hole after the test. The usual packer 



Figure 395. Safety joint. 



