Determination of Regional Dip And Formation Properties From Log Data In a High Angle Well1

An efficient method for determining regional dip angles and formation properties in high angle wells is presented. As a first step, logs are processed to detect similar features. The feature extraction process is speeded up by observing that variation in the formation properties of a high angle well is typically far less than that of a vertical well. Consequently, log data can be appropriately filtered and considerably down-sampled while preserving the essential features of the log. A wavelet-based method is used for multilevel decomposition of log data. Once similar features are recognized, tool trajectory and other information may be combined to select a few features that satisfy certain operating and geological constraints. These features, in conjunction with the logs and tool trajectory, provide an initial set of dip angles and formation parameters. Estimates of dip angles and formation parameters may be improved by an iterative procedure that minimizes the error between computed and measured logs.