Standard Wireline Data Processing



Science operator: Texas A&M University

Hole: U1513A

Expedition: 369

Location: Mentelle Basin (SE Indian Ocean)

Latitude: 33° 47.6084' S

Longitude: 112° 29.1338' E

Logging date: October 23, 2017

Sea floor depth (driller's): 2800.2 m DRF

Sea floor depth (logger's): 2801.2 m WRF

Total penetration: 3092.7 m DRF 292.5 (m DSF)

Total core recovered: 170.6 m ( 58 % of cored section)

Oldest sediment recovered: Cenomanian

Lithology: calcareous ooze, nannofossil ooze with chert, nannofossil chalk, silicified limestone, and clayey nannofossil chalk. 





The logging data were recorded by Schlumberger in DLIS format. Data were processed at the Borehole Research Group of Lamont-Doherty Earth Observatory in October 2017.


Logging Runs

Tool string
Top depth (m WMSF) Bottom depth (m WMSF) Pipe depth (m WMSF) Notes
Caliper closed. Invalid HLDS.
Recorded open hole
Reference depth



The drilling and coring operations at Hole U1513A proceeded without incidents. Prior to logging, the hole was conditioned with sepiolite-seawater (10 lb/gal) mud. Like in the previous hole, the tool string was modified by removing the porosity (APS) tool and replacing it with the sonic (DSI) tool and by moving the gamma ray tool (HNGS) to the bottom in order to get a full signature in the lower part of the hole. The downlog recording was carried out with the caliper closed and proceeded without problems. A repeat pass followed with the caliper open. The main pass, also carried out with the caliper open, experienced some tension over pulls while getting into the drill pipe, which resulted in the gamma ray (HNGS) and density (HLDS) tools detecting the drill pipe at different depths (2879 and 2882 m WRF respectively). The FMS and VSI logs were cancelled due to time constraints.



The average heave was about 1 m with occasional values of 2 m just prior to logging. The motion heave compensator was used whenever the tools were in open hole.


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 match and depth shift to sea floor. The original logs were first depth-matched to the gamma ray log from the main pass of the HRLA/DSI/HLDS/EDTC-B/HNGS 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 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 depth-matched logs were then shifted to the sea floor. The sea floor depth was determined by the step in gamma ray values at 2801.2 m WRF. This differs bym from the sea floor depth given by the drillers (see above).


Environmental corrections. The HNGS, HLDS, and HRLA data were corrected for hole size during the recording.


High-resolution data. The bulk density (HLDS) data were recorded at 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 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. The HRLA was also acquired every 5.08 cm; in the database it was resampled at 15.24 cm, for ease of comparison with the other logs.


Acoustic data. The dipole shear sonic imager (DSI) was operated in the following modes: P&S monopole and upper and lower dipole in all three passses. The sonic velocities were computed from the delay times. They are generally of good 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.


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). When open, the caliper varied from 12 to 16 in, with some locally higher values. Maximum hole deviation was 4 deg.


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 report, Proceedings of the International Ocean Discovery Program, Expedition 369. For further questions about the logs, if the hole is still under moratorium please contact the staff scientist of the expedition.

After the moratorium period you may direct your questions to:


Cristina Broglia

Phone: 845-365-8343

Fax: 845-365-3182

E-mail: Cristina Broglia


Tanzhuo Liu

Phone: 845-365-8630

Fax: 845-365-3182

E-mail: Tanzhuo Liu