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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 [[azimuth]]al 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 [[azimuth]]al 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.

For the results to be geographically significant, it is necessary to define the orientation of the tool in space. This involves continuous measurements of the orientation of the electrode array relative to north, its rotation relative to the high side of the hole, and the inclination of the tool axis from vertical. Such navigation data are produced from the output of an assembly of three orthogonally mounted magnetometers and a similar array of accelerometers. [[:file:dipmeters_fig1.png|Figure 1]] is a sketch of a four-arm tool illustrating the orientation measurements. [[:file:dipmeters_fig2.png|Figure 2]] is an expanded scale recording of the raw dipmeter data showing the orientation curves, calipers, gamma ray, and correlation curves from a six-arm tool. Note that the curves are responding to apparent bedding features less than [[length::1 in.]] thick.

For the results to be geographically significant, it is necessary to define the orientation of the tool in space. This involves continuous measurements of the orientation of the electrode array relative to north, its rotation relative to the high side of the hole, and the inclination of the tool axis from vertical. Such navigation data are produced from the output of an assembly of three orthogonally mounted magnetometers and a similar array of accelerometers. [[:file:dipmeters_fig1.png|Figure 1]] is a sketch of a four-arm tool illustrating the orientation measurements. [[:file:dipmeters_fig2.png|Figure 2]] is an expanded scale recording of the raw dipmeter data showing the orientation curves, calipers, gamma ray, and correlation curves from a six-arm tool. Note that the curves are responding to apparent bedding features less than [[length::1 in.]] thick.