Page 259 - Well Logging and Formation Evaluation

Solutions to Exercises 249

350 360
Width at half max = 12 ft
310
300

260 Direction (deg)
250 210
Field Strength uA/m/A 200 Width at half max = 37 ft 160 Field strength

Field direction
150

100 110
60

50
10
Closest approach at 2795 ft
0 –40
2600 2650 2700 2750 2800 2850 2900
Depth (ft)

The difference cannot be explained, although it may be a combination
of tool accuracy, noise, anisotropy, and variations in target current. Since
most of these factors will affect the two AC magnetometers equally, prob-
ably the range determined from analyzing HS dir is the more accurate of
the two.

CHAPTER 13: WELL DEVIATION, SURVEYING,
AND GEOSTEERING

Exercise 13.1: Formation Dip from Up/Down Logs

Using Equation 13.1 we see that the relative dip is:

q= arctan ( [ .8 5 12 ) ( * 1 3 .281 ) ] = .2 6 2 degrees