Standard Wireline Data Processing


IODP logging contractor: USIO/LDEO

Hole: U1438F

Expedition: 351

Location: Amami-Sankaku Basin (Philippine Sea)

Latitude: 27° 23.0167' N

Longitude: 134° 19.0905' E

Logging date: July 25-26, 2014

Sea floor depth (driller's): 4711 m DRF

Sea floor depth (logger's): 4711 m WRF (MSS/HRLA/HLDS/EDTC-B/HNGS uplog)

Total penetration: 5411 m DRF (700 m DSF)

Total core recovered: none, this hole was dedicated to logging

Lithologies:  Mud with ash, turbidites, conglomerates, breccia, and sandstone were drilled at hole U1438D




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 July 2014.


Logging Runs

Tool string
Top depth (m WMSF) Bottom depth (m WMSF) Pipe depth (m WMSF)

Closed caliper; invalid HLDS and APS

Reference run
Open hole
Recorded open hole
Closed caliper; invalid FMS



This is a dedicated logging hole with excellent condition. After drilling completion, only seawater was used to prepare the hole and a wiper trip was scheduled due to the bridging encountered at the depth of 300 m DSF. Ship heave was low (0.3 m from peak to peak) and the wireline heave compensator was used during the logging operations.


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 (-4711 m). The sea floor depth was determined by the step in gamma ray values on the uplog at 4711 m WRF, which is consistent with the drillers' seafloor depth of 4711 m DRF. The depth-shifted logs have then been depth-matched to the gamma ray log from the downlog.


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 and HRLA data were corrected for hole size during the recording. The APS and HLDS data were corrected for standoff and hole size respectively during the recording.


High-resolution data. Bulk density (HLDS) and neutron porosity (APS) data were recorded at 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 ones, 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.


Acoustic data. The dipole shear sonic imager (DSI) was operated in P&S monopole, Stoneley, upper and lower dipole mode during the uplog and in monopole mode during the downlog. The monopole and upper dipole were run at standard frequency and the lower dipole at low frequency. All sonic modes provided excellent data but the standard frequency upper dipole shear was generally better than the low frequency lower dipole shear. Stoneley and compressional data were excellent through most of the logging interval. Velocity has been calculated from DTCO, DT1, DT2 and DTST.




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 (APS, HLDS). Hole diameter was recorded by the hydraulic caliper on the HLDS tool (LCAL). Since this is a dedicated logging hole with excellent condition, the hole size was largely ideal for logging and the quality of the density and porosity logs was excellent.


The SP measurement was surprisingly good; historically the SP has always been very elusive in obtaining any good deflections in ODP/IODP holes.  The SP logs correlate well with resistivity and density/porosity.


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 351. 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