1. Well Log Data
Processing
Prepared By:
SHOAIB AAMIR FAHIM

2. Well log Processing.
Integrated interpretation of any geological model requires
cautious grounding and judicious use of petrophysical logs and
other well-derived data.
The main purpose of well log processing is to prepare the well
data for interpretation.
Processing steps varies according to Company/Client and
availability/Quality of data.

3. Well Log Data Processing Steps
 Data Check.
 Depth Shifting.
 Removal of End Effects.
 SP baseline shift.
 Rescaling.
 Patching
 Block editing.
 Splicing /Construct composite curve.
 Value Edit
 Tabular Edit.
 Fill Gaps.
 Data Quality check.
 Final Report.

4. Data Check
Review how many Logs and its digital are provided by client.
If digital is missing then these logs/curves need to be digitize.
Read header information.
Data Loading
 Load digital data in provided software for processing.
Depth Shifting
 Depth shifting enables to shift curve data relative to a reference
curve (GR or Deep Resistivity e.g. LLD, LN).
 The measurements from each tool are aligned to a common depth.
 Two ways to depth shift curve data.
1.Bulk Depth Shift.
2.Multiple tie line Depth Shift.

5. 1. Bulk Depth Shift.
 Single shift to an off-depth curve and graphically tie it to your reference
curve.
 This single shift is applied to all curve depths.
2. Multiple Tie Line Depth Shifting.
 Multiple points on an off-depth curve and graphically tie them to points
on your reference curve.
 Stretch or compress a portion of an off-depth curve using this method.

6. Bulk depth shifting procedure.

7. Multiple Tie Line Depth Shifting Procedure.

8. Removal of End Effect.
The curve response other then the response of lithology.
Such as response of curve in casing or tool response at the start
and at the end of logging.
End effect
Curve before end Curve After end
effect removal effect removal

9. Baseline Shifting.
Baseline shift is primarily designed for correcting SP curve drift.
Removal of SP baseline drift aids the automatic computation of
water resistivity and shale volume over long depth interval.
-ve SP.
When ions of NaCl moves from formation water to mud filtrates
then generated SP called –ve SP.
+ve SP.
When ions of NaCl moves from mud filtrates to formation water
then generated SP called +ve SP.

10. GR
SN
-ve SP
Deflection
SP
LN
+ve SP
Deflection

11. Baseline shift Procedure(-ve & +ve SP)
SP baseline Shift
for –ve SP
SP baseline Shift
for +ve SP

12. SP curve before SP curve After
baseline shift baseline shift
Baseline
-ve SP
+ve SP

13. Rescaling
Rescale allows for correction of improper calibration and missed
scale changes of digitized logs.
It also allows for convertion of linear scale to logarithmic scale (and
vise versa).
SP curve before SP curve After
Rescaling Rescaling

14. Patching curves.
Patching curves allows you to interactively digitize points on the
screen using Mouse Button 1.
Patch curves use to remove unwanted data points, such as
noise spikes, and to reshape curves.
Editing of sonic for cycle skipping and density for any borehole
washout.

15. Patching Curve Procedure.

16. Block Editing
Block editing enables to “square” or visually average curve intervals.
It is typically used to block sonic and density logs for generating
synthetic seismograms and determining acoustic impedence.

17. Splicing or Construct composite
Splicing curves merges segments together at one time.
This is useful for merging curves from different logging runs into a
single composite curve.

18. Value Editing
Value editing enables you to change the value at a data point on the
selected curves by typing a new value.

19. Tabular Editing
Tabular editing provides a graphical interface for digitally changing
individual curve value at selected depth.
This is useful when only a limited number of values need adjusting.

20. Tabular editing procedure.

21. Fill Gaps.
Fill Gap is used to replace nulls with values interpolated
between valid data points.

22. Data Quality Check.
QC job perform To ensure the quality of processing.
QC person check the processed data thoroughly before
delivering to client.
If there is any flaw in processed data then need to be
reprocessed.
Final Report
After the data quality assurance, write the final report.
Final report express or define all processing steps, curve
details & comments regarding data.

23. Thank You