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→Dipmeter data acquisition
==Dipmeter data acquisition==
==Dipmeter data acquisition==
<gallery mode=packed heights=300px widths=300px>
[[file:dipmeters_fig1.png|left|thumb|{{figure number|1}}Sketch of a four-arm dipmeter tool illustrating pertinent orientation measurements.]]
[[file:dipmeters_fig1.png|{{figure number|1}}Sketch of a four-arm dipmeter tool illustrating pertinent orientation measurements.
[[file:dipmeters_fig2.png|{{figure number|2}}Expanded scale recording of raw dipmeter data from a six-arm tool.
[[file:dipmeters_fig2.png|thumb|{{figure number|2}}Expanded scale recording of raw dipmeter data from a six-arm tool.]]
</gallery>
The determination of dip angle and direction of a planar surface requires the elevation and geographical position of at least three points. Dipmeter tools achieve this result by measuring some sensitive formation parameter by means of three or more identical sensors mounted on caliper arms so as to scan in detail different sides of the borehole wall. A bedding plane crossing the borehole at an angle would generate anomalies at each sensor, and these anomalies would be recorded at slightly different depths on the surface recording. The relative displacements and the radial and azimuthal positions of each sensor are then used to compute dip relative to the tool. Microresistivity has been the traditional formation parameter logged. Modern dipmeter tools usually carry more than three sensor arms, the latest version being a device with six arms. More measure points provide the advantage of systematic redundancy, which allows the application of statistical error minimization techniques.
The determination of dip angle and direction of a planar surface requires the elevation and geographical position of at least three points. Dipmeter tools achieve this result by measuring some sensitive formation parameter by means of three or more identical sensors mounted on caliper arms so as to scan in detail different sides of the borehole wall. A bedding plane crossing the borehole at an angle would generate anomalies at each sensor, and these anomalies would be recorded at slightly different depths on the surface recording. The relative displacements and the radial and azimuthal positions of each sensor are then used to compute dip relative to the tool. Microresistivity has been the traditional formation parameter logged. Modern dipmeter tools usually carry more than three sensor arms, the latest version being a device with six arms. More measure points provide the advantage of systematic redundancy, which allows the application of statistical error minimization techniques.