example cited by Hurst may be worked with this method and close agreement will 

 be obtained. This is coincidental because the values of 



V 4kt ) 



happen to be consistent with (D.R.) = 1. 



APPENDIX C The theory of barrier detection stated by 



Horner (1951) is based on the superposition 

 Barrier Detection of solutions of two equations, one for the well 



itself, and the second for its image reflected 

 from the linear barrier at a distance, b, from the producing well. Horner con- 

 cludes that the following equation is satisfied at the intersection of the two 

 straight lines: 



-K-^M-^) 



t 4- B 

 Let D = — °—- at the intersection of the two straight lines. 







Assuming that ~- — < .01; 



kt 



n b 2 f*c ~\ 



then - In — — + .5772 = In D ; (24) 



then b * = IM j^D > < 25 > 



which is in cgs units. 



Converting to field units, 



ht 

 b 2 = 3.622 X 10 " 5 , ° (26) 



ffxcD 



Selecting typical values for the reservoir terms, 



/ = io- 1 



jx = 1 cp 



c = 3.6 X 10 ~ 5 atm" 1 



D = 10 

 760 



