. Deep borehole surveys and problems. Boring. 274 DEEP BOREHOLE SURVEYS AND PROBLEMS angle CFCi = 8, the full dip of the stratum. The angles ^1 and a also the lengths ACi and CCi are known. and or tan 5 = FCi = ACi sin di cc. CC, tan a FCi ACi sin di sin di tan 8 = tan a cosec di (62) Given Three Deviated Boreholes to Determine the Dip and Strike of the Stratum.—Having surveyed three bore-. FiG. 183. holes A, B and C and found their net horizontal displace- ments and depths a line may be drawn in a direction connecting the source and end of each. This line will usually be the shortest line bet
. Deep borehole surveys and problems. Boring. 274 DEEP BOREHOLE SURVEYS AND PROBLEMS angle CFCi = 8, the full dip of the stratum. The angles ^1 and a also the lengths ACi and CCi are known. and or tan 5 = FCi = ACi sin di cc. CC, tan a FCi ACi sin di sin di tan 8 = tan a cosec di (62) Given Three Deviated Boreholes to Determine the Dip and Strike of the Stratum.—Having surveyed three bore-. FiG. 183. holes A, B and C and found their net horizontal displace- ments and depths a line may be drawn in a direction connecting the source and end of each. This line will usually be the shortest line between these points and will have the average deflection of the hole throughout. Let us consider a concrete case of three holes set vertically but now deviated until when reduced as above we get their bases data also. Let the surface and borehole data be: Coordinates Net bearing of hole Length of hole, feet Dip from horizontal (90 — off vertical), degrees X Y A B C 1, °E. °E. °E. 1,200 300 400 60 75 80 These points are set out in ABC (Fig. 184),. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Haddock, M. H. (Marshall Henry). New York, McGraw-Hill
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