wells in these areas provide satisfactory levels for dip determinations at almost 

 any position in a well. 



FIELD PROCEDURE Dipmeter surveys are made with the same 



cable and, as noted above, surface-recording 

 equipment used for electric logging. Common practice is to make the dipmeter 

 run immediately after the electric logging. 



The dipmeter levels must be chosen from the electric log. The assembly — 

 electrodes, photoclinometer, and spring guides — is lowered to the base of the 

 shallowest level and a photoclinometer picture taken. This picture determines 

 the orientation of the electrodes and the curves, as well as the drift and azimuth 

 of the well bore at the base of the level. The curves are recorded to the top of 

 the level, and a second photoclinometer picture is taken. The latter gives the 

 orientation of the electrodes and the curves, as well as the drift and azimuth of 

 the well bore at the top of the level. After this step, the assembly is lowered to 

 the base of the second-shallowest level, and the procedure given above is repeated. 

 Other levels are recorded in the same manner. 



After the deepest level has been recorded, it is resurveyed with a photo- 

 clinometer picture taken in the middle of the level as well as at the top and base. 

 Each of the higher levels, similarly, is repeated as the equipment is withdrawn 

 from the hole, 



INTERPRETATION All dipmeter surveys are analyzed by a staff 



specializing in such work, and two independ- 

 ent interpretations are made for each operation. Likewise, the data from the 

 original and check runs on each level, generally recorded with different electrode 

 orientations, must agree, or the results are discarded. After the orientation of 

 the curves, their displacement, and the drift and azimuth of the well bore have 

 been determined over the interval of a level, the magnitude and direction of the 

 dip are obtained quickly by mechanical means. 



A typical computation sheet is shown in Figure 19-2. The first column 

 designates the level; AA1, for example, is the original run, AA2, the check 

 run, etc. The second column gives the depth interval of the level. The third 

 column shows the azimuth of the well in degrees from magnetic north ; the fourth 

 column the drift angle. The fifth column is the position of the No. 1 recording 

 electrode in degrees from magnetic north. The sixth and seventh columns indi- 

 cate the displacement in inches of curves recorded on electrodes two and three 

 with respect to the No. 1 curve. The last three columns give the amount and 

 direction of the dip computed from the previous data. 



391 



