Standard Wireline Data Processing


IODP logging contractor: USIO/LDEO

Hole: U1417E

Expedition: 341

Location: Gulf of Alaska (NE Pacific Ocean)

Latitude: 56° 57.5888' N

Longitude: 147° 6.5983' W

Logging date: June 20-21, 2013

Sea floor depth (driller's): 4199.5 m DRF

Sea floor depth (logger's): 4200 m WRF

Total penetration: 4909 m DRF (709.5 m DSF)

Total core recovered: 146.92 m (42.1 % of 348.7 m; several drilled-down intervals)

Oldest sediment recovered: ~5 Ma at 400 m DSF

Lithologies:  Mud, iceberg-rafted diamict, coarse-grained interval dominated by gravity flows alternate with mud, siltstone and sandstone.




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 June 2013.


Logging Runs

Tool string

Top depth (m WMSF)

Bottom depth (m WMSF) Pipe depth (m WMSF) Notes
Downlog 1

Invalid APS/HLDS. Caliper closed.

Downlog 2
recorded open hole
Invalid APS/HLDS. Caliper closed.
Depth reference
Calipers closed.
Pass 1
Pass 2
Pass 1
Pass 2
4. VSI
2 good stations at 211.3 and 211.9 m WSF



Logging operations in Hole U1417E started with conditioning of the hole without wiper trip and used seawater as logging fluid. The first "triple-combo" tool string (MSS/HLDS/APS/EDTC-B/HNGS) acquired data downlog to a depth of 4824 m WRF (624 m WSF), with problems of loss of tension occurred at several tight spots or bridges. Both repeat and main logs were then recorded without problems. The second tool string (FMS/DSI/GPIT/EDTB-B/HNGS) acquired data downlog to a depth of 4778.5 m (578.5 m WSF), where an obstruction was encountered; two uplog passes were then recorded. During the third deployment, the full MSS-B tool string was used for the first time. It reached a total depth of 4404 m WRF (204 m WSF) and acquired one downlog and two uplogs. The VSI tool string was run last. It reached a total depth of 4395 m WRF (195 m WSF) and acquired only two good shots (at 1411.3 and 1411.9 m WRF) though 50 shots were fired.


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.


The sea state was calm, with peak-to-peak heave of 0.5-1 m. The wireline heave compensator was used during all of the logging runs.




Depth shift to sea floor and depth match. The original logs were first shifted to the sea floor (- 4200 m). The sea floor depth was determined by the step in gamma ray values at 4200 m WRF. This differs by 0.5 m from the sea floor depth given by the drillers (see above). The depth-shifted logs were then depth-matched to the gamma ray log from the main pass of the MSS/HRLA/APS/HLDS/EDTC-B/HNGS tool string.


Depth matching is typically done in the following way. One log is chosen as reference or 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 are 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.


The drill pipe depth between the triple-combo main pass and passes from the other logging runs differs about 2-4 m, likely due to the poor hole conditions and related stick-slip motion of the tool strings.



Environmental corrections. The HNGS data were corrected for hole size and mud weight after the recording. The APS and HLDS data were corrected for standoff and hole size respectively after the recording.


High-resolution data. Bulk density (HLDS) and neutron porosity (APS) data were recorded with sampling rates of 2.54 and 5.08 cm, respectively, 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 are 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. 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 (downlog and 2 passes) and cross-dipole (pass 1) in standard (high) frequency, upper and lower dipole (downlog and 2 passes) in high and low frequency, respectively, and Stoneley (downlog and 2 passes). Low frequency dipole had the best slowness projection mostly below 4500 m WRF (or 300 m WSF). There were some missed picks in the compressional velocity in the upper part of the hole, as the auto picking could not distinguish between the compressional and fluid velocity. The velocities were computed from the delay times. Waveform processing is recommended to improve quality.


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.


The data from the MSS/HRLA/APS/HLDS/EDTC-B/HNGS tool string are of variable quality. The density, resistivity, and gamma ray logs are very noisy in the uppermost 300 m of the hole section due to poor hole conditions, with some improvement below that depth. The MSS acquired good data show a clear downhole drift, possibly attributed to increase in tool temperature downhole.


A wide (>12") and/or irregular borehole affects most recordings, particularly those that require eccentralization and a good contact with the borehole wall (APS, HLDS). Hole diameter was recorded by the hydraulic caliper on the HLDS tool (LCAL) and by the FMS tool (C1 and C2). The caliper shows a very irregular borehole (4 to 18 inches), with variations of up to 13 inches in just a few meters of vertical depth. Accordingly, log data from such wash-out intervals should be used with caution.


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 341. 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