| 摘要 |
<p>In a well logging truck computer which produces an induction log, a Dip correction Algorithm stored in a memory therein corrects an error introduced in the induction log by dip effect the correction involving multiplying or convolving inverse filters "h" as a function of dip angle "a" with a plurality of the previously incorrect formation parameter data "sigma (j-n) to thereby produce a corresponding plurality of corrected formation parameter data "sigmaF", the corrected formation parameter data being reproduced on a record output medium. The inverse filters "h" are computed using log response functions derived from simple dipping formation models. The dip effect results by disposing an array induction tool in a deviated borehole at an apparent dip angle with respect to a formation having a plurality of bedding planes. In a preferred embodiment, the explicit algorithm for doing dip correction with filters derived from step-profiles involves the following steps: step (1): Determine an apparent dip angle from dip and deviation and identify the two nearest defined dip angles (a1 and a2) which provide a bound around the apparent dip angle; step (2): Convert the ran, calibrated induction channel data to True Bed Thickness (TBT) format and resample the converted data on a six-inch interval in TBT mode; step (3): Process the converted, resampled induction channel data in TBT format using a predefined phasor algorithm to produce induction deep phasor (IDPH) and induction medium phasor (IMPH) signals sigma CDPHTBT and sigma CMPHTBT, respectively; step (4): Using equation 13, process each of the resulting signals sigma CDPHTBT and sigma CMPHTBT with two filters h(a1) and h(a2), where filter h(a1) and h(a2) are a function of the two nearest defined dip angles a1 and a2 to thereby produce two values "sigmaF" for each of the signals sigma CDPH<TBT> and sigma CMPH<TBT>, the two values "sigmaF" being formation parameters (such as conductivity) associated with a formation traversed by a borehole at the two nearest defined dip angles; step (5): given the two values "sigmaF" of step (4) and the two corresponding respective nearest defined dip angles a1 and a2 of step (1), and given the apparent dip angle determined in step (1), interpolate to determine a new value "sigmaF" corresponding to the apparent dip angle; step (6): Do a "akin effect" correction on the new value "sigmaF" of step (6); and step (7): If required, convert back from TBT format to borehole depth for comparison to field log data. <IMAGE></p> |
