IODP Expedition 320, Hole U1332A - Wireline Standard Data"> IODP Expedition 320, Hole U1332A - Wireline Standard Data

Standard Wireline Data Processing


IODP logging contractor: USIO/LDEO

Hole: U1332A

Expedition: 320

Location: Equatorial Pacific Sediment Mound (Eastern Equatorial Pacific)

Latitude: 11° 54.711 ' N

Longitude: 141° 02.744 ' W

Logging date: March 24-25, 2009

Sea floor depth (driller's): 4935.1 mbrf

Sea floor depth (logger's): 4935.1 mbrf

Total penetration: 5087.5 mbrf

Total core recovered: 145.61 m (99.1 % of cored section)

Oldest sediment recovered: Middle to late Eocene

Lithologies:  Nannofossil ooze, radiolarian ooze with clay, and 10 cm of basalt at the base



The logging data was recorded by Schlumberger in DLIS format. Data was processed at the Borehole Research Group of the Lamont-Doherty Earth Observatory in March 2009.


Logging Runs



Tool string


Top depth (mbsf)

Bottom depth (mbsf)

Pipe depth (mbsf)







Caliper closed.














Logging operations started with the MSS/HLDS/HNGS string, which recorded data downlog first and then uplog (2 passes). No problems were encountered during these runs. However, when the tool string was being retrieved after pass 2, it was lost in hole. As a result, the FMS/GPIT/HNGS tool string was not run as planned. The caliper was kept open during the first and second passes, but closed during the downlog.


The WHC was not operated throughout the logging operations due to malfunction. The sea state was rough, with heave of about 2 meters.


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 (- 4935.1 m). The sea floor depth was determined by the driller's depth (- 4935.1 mbrf), rather than by the step in gamma ray values (logger's depth), for these logs didn't run through the sea floor. The depth-shifted logs were then depth-matched to the gamma ray log from pass 2 of the MSS/HLDS/HNGS tool string. Pass 2 was chosen as the reference because it was the longest among the three logs.


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


Magnetic susceptibility data. The magnetic susceptibility tool (MSS) was run for all three passes. At the time of this processing the recorded data has not been calibrated yet and therefore is not presented in ASCII file format in the online database. It will be included at a later date.


High-resolution data. Bulk density (HLDS) data was recorded at sampling rates 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. 

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).


Despite the lack of calibration of the susceptibility log, there is generally good correlation among the downlog and uplog passes for the low-resolution susceptibility logs. More processing after calibration is required to produce final results.


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.


Hole diameter was recorded by the hydraulic caliper on the HLDS tool (LCAL). The caliper was kept closed during the downlog and open during the uplogs.  It ranged from 12 to 20", with the higher values recorded above 117 mbsf. A wide (>12") and/or irregular borehole affects most recordings, particularly those that require eccentralization and a good contact with the borehole wall (HLDS). Therefore, log data from the upper portion of the hole and bulk density data from the downlog (no correction for borehole size) 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 320. 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