Dual Propagation Resistivity
3. Realtime vs. Relog Data Comparison
• A quantitative log is required for adequate evaluation. After a relog (second pass) is performed, it is important to plot the memory relog data with the "original pass" realtime data.
Plot realtime and memory gamma ray in track I and original pass realtime Rpdwith memory relog Rpdin track II. It is not necessary to plot Rat. Evaluate this data for depth shifts. If depth shifts are identified, call the office for
recommendations.
• If memory relog data is merged with "on bottom" data, a composite log that contains the realtime "on bottom" data and the memory merged relog data should be plotted and evaluated for depth discrepancies. Plot the realtime "on bottom" and the memory merged relog gamma ray together in track I. Plot the realtime "on bottom" and the merged relog Rpdin track II. It is not necessary to plot Rat. If depth discrepancies occur, call the office for recommendations.
Log Quality and Data Management Standards Dual Propagation Resistivity
Typical Log Response
Gamma Ray
The gamma ray sensor is primarily a lithology indicator. It measures the natural gamma ray radiation that is emitted from naturally occurring radioactive elements (uranium, thorium, and potassium) deposited within the surrounding formations. As it turns out, shale generally contains much higher quantities of these radioactive substances than sandstones and carbonates (limestone and dolomite). Therefore, the gamma ray sensor can, in most cases, easily distinguish between shales and non-shale formations.
• Shales are generally identified by high gamma ray readings (greater than 100 MWD-API units).
• Non-shale formations (sandstones and carbonates) are identified by relatively low gamma ray readings (lower than 60 MWD-API units).
Dual Propagation Resistivity
After borehole corrections have been applied and relatively standard borehole conditions exist, the following relationships between Rpd and Rat
should apply.
Permeable Zones
When Rmf< Rw , then Rpd< Rat
When Rmf> Rw , then Rpd> Rat
In both cases, the amount of separation will depend on the depth of invasion, the relative values of Rmf , Rw, and the filtrate and water saturations.
Impermeable Zones (Shales) When Rmf< Rw , then Rpd ≤ Rat
When Rmf> Rw, then Rpd ≥ Rat
Dielectric Formations Rpd < Rat
Dual Propagation Resistivity Log Quality and Data Management Standards Thin Beds Intersecting Borehole at High Incident Angles
(Above 80°) Rpd > Rat
Eccentricity
Typically, no effect unless a large contrast between Rmand Rtexists (either Rmmuch greater than Rt , or Rt much greater than Rm ). Under these
circumstances Rpd< Rat.
Other Requirements for This Service
Surface measurement of Rm and Rmfcorrected for bottom-hole circulating temperature required on a daily basis. This data should be supplied on the header of each daily log with BHCT (see “Main Header, Environmental Parameters” on page 3-8 for measurement procedures).
Log Quality and Data Management Standards Dual Propagation Resistivity
Log Presentation
Note: All log formats listed below assume the data is either realtime or memory data that has been processed without a P-SERIES system (or with a P-SERIES system "without averaging" selected for processing) and plotted using MPLOT. In cases where a P-SERIES system was used and the data was processed using the "averaging" option, then it is recommended not to smooth during plotting.
This will result in over smoothed logging traces. This will most frequently affect the Gamma Ray MWD API trace.
North and South America Log Presentations
1:600 AND 1:1200 ENGLISH LOG FORMATS
Track 1: Linear Track 2: Linear Track 3: Linear
Trace Track Param Ledge Redge Line Mode Smooth Pen Up Notes
1
Dual Propagation Resistivity Log Quality and Data Management Standards 1:240 ENGLISH DEFAULT LOG FORMAT (quantitative)
1. TVD: Optional trace used specifically for horizontal well applications. Scale increases from right to left.
2. TCDM: Scale increases from left to right.
3. RPIM: The output and presentation of this trace is predetermined. However, a number must be input into these parameters to prevent MPLOT from crashing. Presentation is in the depth track.
ALTERNATE 1:240 ENGLISH LOG FORMAT (quantitative)
1. RPTM: Since tracks 2 and 3 contain a logarithmic grid and time since drilled is a linear curve, plot the time since drilled trace in track 1.
2. TVD: Optional trace used specifically for horizontal well applications. Scale increases from right to left.
3. RPIM: The output and presentation of this trace is predetermined. However, a number must be input into these parameters to prevent MPLOT from crashing. Presentation is in the depth track.
Track 1: Linear Track 2: 2 Cycle Log Track 3: Linear
Trace Track Param Ledge Redge Line Mode Smooth Pen Up Notes
1
Track 1: Linear Track 2: 2 Cycle Log Track 3: 2 Cycle Log
Trace Track Param Ledge Redge Line Mode Smooth Pen Up Notes
1
Log Quality and Data Management Standards Dual Propagation Resistivity International Log Presentations
1:500 METRIC LOG FORMAT (correlation)
1:200 METRIC LOG FORMAT (quantitative)
1. TCDM: Default units are Celsius. Other default units and scales are 0 - 250° Fahrenheit.
2. TVD: Optional trace used specifically for horizontal well applications. Scale should increase from left to right.
3. ROPS: Default units are ft/hr. Other default units and scales are 100 - 0 m/hr, 60 - 0 min/ft, 60 - 0 min/m, 10 - 0 ft/min, 10 - 0 m/min. Default for averaging is also feet.
Metric equivalent is 2.0 (for 1:500 metric) and 1.0 (for 1:200 metric).
4. WBCS: Default units are K-lbs. Optional units and scales are 0 - 50 Tonnes, 0 - 500 KN.
5. RPIM: The output and presentation of this trace is predetermined. However, you must input a number in these parameters to prevent MPLOT from crashing. Presentation is in the depth track.
Note: Pen up intervals are in feet. Metric equivalent is 3 meters (for 10 feet) and 30 meters (for 100 feet).
Track 1: Linear Track 2: 2 Cycle Log Track 3: Linear
Trace Track Param Ledge Redge Line Mode Smooth Pen Up Notes
1
Track 1: Linear Track 2: 2 Cycle Log Track 3: Linear
Trace Track Param Ledge Redge Line Mode Smooth Pen Up Notes
1
Dual Propagation Resistivity Log Quality and Data Management Standards
ALTERNATE 1:200 METRIC LOG FORMAT (quantitative)
1. ROPS: Default units are ft/hr. Other default units and scales are 100 - 0 m/hr, 60 - 0 min/ft, 60 - 0 min/m, 10 - 0 ft/min, 10 - 0 m/min. Default for averaging is also feet.
Metric equivalent is 2.0 (for 1:500 metric) and 1.0 (for 1:200 metric).
2. TCDM: Default units are Celsius. Other default units and scales are 0 - 250°°F.
3. TVD: Optional trace used specifically for horizontal well applications. Scale should increase from left to right.
4. RPIM: The output and presentation of this trace are predetermined. However, you must input a number in these parameters to prevent MPLOT from crashing.
Presentation is in the depth track.
Track 1: Linear Track 2: 2 Cycle Log Track 3: 2 Cycle Log
Trace Track Param Ledge Redge Line Mode Smooth Pen Up Notes
1
Chapter