Miscellaneous Subsurface Methods 



745 



comes from the expansion and contraction of a Spiral Bourdon tube from 

 which it gets its name. (fig. 398) . Although delicate in construction, by 

 using certain precautions it is possible to obtain very accurate recordings 

 without destruction. Because it is highly sensitive to reaction, slight varia- 

 tion of pressure changes are recorded which to a certain degree have im- 



FiGURE 399. Chart from standard pressure-recording device: (a) test started; {b) 

 reached packer seat; (c) packer seated; (d) tester opened; (e) flowing pres- 

 sure; (/) tested closed; (g) closed-in formation pressure; (h) packer unseated; 

 (i) started out of hole; (y) reached surface. 



