WellogRevive

Handling Complex Historical Well Logs

Recovering Data from Complex Historical Well Logs

Historical well logs rarely follow a single format. Curve scales, track geometry, depth layouts, and presentation styles can vary significantly between wells, operators, and recording periods. Effective digitization therefore requires more than simple curve tracing. It requires careful calibration of scales, depth references, and track geometry to preserve the original measurements.

The digitization workflow supports a variety of historical log configurations, including multi-section logs, dual-scale curve presentations, reverse scales, and distorted track geometries. Each log is calibrated according to its original structure to ensure that depth relationships and numerical values are retained throughout the digitization process.

Capabilities include:

• Multi-section logs

• Multi-curve digitization

• Dual-scale Gamma Ray recovery

• Reverse scale handling

• Trapezoidal track correction

• Variable track-width calibration

• CSV, LAS, ASCII and Excel outputs

• High-resolution digital reconstruction

Excel outputs, same depths different curves, GR, Conductivity and SP

Trapezoidal Track Correction

Calibrating Historical Logs with Variable Track Geometry
Historical well logs frequently contain non-rectangular track geometries caused by original printing techniques, paper distortion, scan skew, or aging records. Assuming fixed track boundaries can introduce measurement errors where track width and position vary with depth.
To preserve scale accuracy, track boundaries are calibrated independently at the top and bottom of each section. These boundaries are then continuously interpolated throughout the depth interval, allowing the digitization process to follow the actualgeometry of the historical log rather than an idealized rectangular track.
This approach improves scale consistency and supports reliable data recovery from distorted or irregular historical records.

Multi-Curve Historical Log Recovery

Historical well logs frequently contain several measurements presented within the same record. Each curve may use a different scale, response range, and presentation style while still sharing a common depth reference. Accurate digitization requires each measurement to be calibrated independently while preserving depth alignment throughout the log. This process transforms multiple graphical measurements into structured digital datasets while maintaining the original relationships between curves and recorded observations.

Some historical records also contain measurements that extend beyond the visible limits of their assigned track. In these cases, the recorded curve continues beyond the track boundary and reappears elsewhere on the log. Accurate reconstruction requires identifying and preserving these curve continuations while maintaining the original measurement scale, depth relationships, and geological meaning of the original record.

Curve continuation beyond track boundaries. Historical records may contain measurements that extend outside their assigned track, requiring careful interpretation and reconstruction during digitization.

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