Standard Wireline Data Processing


IODP logging contractor: USIO/LDEO

Hole: U1425B

Expedition: 346

Location: Yamato Rise (Japan Sea)

Latitude: 39° 29.4476' N

Longitude: 134° 26.5502' E

Logging date: August 30, 2013

Sea floor depth (driller's): 1919 m DRF

Sea floor depth (logger's): 1916.7 m WRF (FMS/DSI/GPIT/EDTC-B/HNGS Main Run)

Total penetration: 2326.2 m DRF (407.2 m DSF)

Total core recovered: 397.25 m (97.6 %)

Oldest sediment recovered: Miocene

Lithologies:  Biosiliceous clay, silty clay, diatom ooze and claystone


The logging data was recorded by Schlumberger in DLIS format. Data were processed at the Borehole Research Group of the Lamont-Doherty Earth Observatory in September 2013.


Logging Runs

Tool string
Top depth (m WMSF) Bottom depth (m WMSF) Pipe depth (m WMSF) Notes
Closed caliper; invalid HLDS
Recorded open hole
Closed caliper; invalid FMS
Recorded open hole
Depth reference



The logging operations at Hole U1425B were uneventful. Since no major incidents were encountered during drilling, the preparations for logging consisted of bottom circulation only.


The sea state was moderately high with peak-to-peak heave of ~ 0.8-2 m or less. The wireline heave compensator was used during the logging operation, but with poor compensation performance.


The depths in the table are for the processed logs (after depth shift to the sea floor and depth matching between passes). Generally, discrepancies may exist between the sea floor depths determined from the downhole logs and those determined by the drillers from the pipe length. Typical reasons for depth discrepancies are ship heave, wireline and pipe stretch, tides, and the difficulty of getting an accurate sea floor from a 'bottom felt' depth in soft sediment.




Depth shift to sea floor and depth match. The original logs were first shifted to the sea floor (- 1916.7 m). The sea floor depth was determined by the step in gamma ray values at 1916.7 m WRF. This differs by 2.3 m from the sea floor depth given by the drillers (1919 m DRF). The depth-shifted logs have then been depth-matched to the gamma ray log from the main run of the FMS/DSI/GPIT/EDTC-B tool string.


Depth matching is typically done in the following way. One log is chosen as reference (base) log (usually the total gamma ray log from the run with the greatest vertical extent and no sudden changes in cable speed), and then the features in the equivalent logs from the other runs are matched to it in turn. This matching is performed manually. The depth adjustments that were required to bring the match log in line with the base log are then applied to all the other logs from the same tool string.


Environmental corrections. The HNGS data were corrected for hole size and mud weight during the recording. The EDTC-B and HLDS data were corrected for hole size during the recording.


High-resolution data. The bulk density (HLDS) data were recorded with a sampling rate of 2.54 cm in addition to the standard sampling rate of 15.24 cm. The enhanced bulk density curve is the result of Schlumberger enhanced processing technique performed on the MAXIS system onboard. While in normal processing short-spacing data is smoothed to match the long-spacing one, in enhanced processing this is reversed. In a situation where there is good contact between the HLDS pad and the borehole wall (low-density correction) the results are improved, because the short spacing has better vertical resolution. The gamma Ray data from the EDTC-B tool were recorded at sampling rates of 5.08 and 15.24 cm. 


Acoustic data. The dipole shear sonic imager (DSI) was operated in the following modes: P&S monopole, upper and lower dipoles, and Stoneley on all three runs with standard frequency, except for the lower dipole mode during the downlog when low frequency was used, resulting in data compared unfavorably with those from the upper dipole. The lower dipole was then switched back to standard frequency for both repeat and main log recordings. Sonic waweform processing is recommended to obtain improved results.



Quality Control


The quality of the data is assessed by checking against reasonable values for the logged lithologies, by repeatability between different passes of the same tool, and by correspondence between logs affected by the same formation property (e.g. the resistivity log should show similar features to the sonic velocity log).


Gamma ray logs recorded through bottom hole assembly (BHA) and drill pipe should be used only qualitatively, because of the attenuation of the incoming signal. The thick-walled BHA attenuates the signal more than the thinner-walled drill pipe.


A wide (>12") and/or irregular borehole affects most recordings, particularly those that require eccentralization and a good contact with the borehole wall (HLDS). Hole diameter was recorded by the hydraulic caliper on the HLDS tool (LCAL) and by the FMS tool (C1 and C2). The caliper measurements show that the hole size was relatively large (12-16 ") for most of the hole interval. In addition, the heave compensator didn't perform as expected during the logging operations while the sea state was moderately high. Both of which might have detrimentally affected data recordings.


A null value of -999.25 may replace invalid log values.


Additional information about the drilling and logging operations can be found in the Operations and Downhole Measurements sections of the expedition reports, Proceedings of the Integrated Drilling Program, Expedition 346. For further questions about the logs, please contact:



Tanzhuo Liu

Phone: 845-365-8630

Fax: 845-365-3182

E-mail: Tanzhuo Liu


Cristina Broglia

Phone: 845-365-8343

Fax: 845-365-3182

E-mail: Cristina Broglia