Standard Wireline Data Processing



Science operator: Texas A&M University

Hole: U1467E

Expedition: 359

Location: Maldives (Central Equatorial N Indian Ocean)

Latitude: 4° 51.0362' N

Longitude: 73°17.0197' E

Logging date: November 5-6, 2015

Sea floor depth (driller's): 499.5 m DRF

Sea floor depth (logger's): 499.5 m WRF (MSS/HRLA/APS/HLDS/EDTC-B/HNGS main run)

Total penetration: 1212.4 m DRF (712.9 m DSF)

Total core recovered: dedicated logging hole, no core recovered

Oldest sediment recovered: see Hole U1467C

Lithology: see Hole U1467C





The logging data were recorded by Schlumberger in DLIS format. Data were processed at the Borehole Research Group of the Lamont-Doherty Earth Observatory in November 2015.


Logging Runs

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

Closed caliper. Invalid HLDS and APS data.

recorded open hole
APS nuclear source off. Invalid APS.
recorded open hole
13 stations, 94 shots.
Calipers closed. Invalid FMS data.
Pass 1
recorded open hole
Pass 2



Hole U1467E was a logging-dedicated hole, therefore no coring was carried out. Hole conditions were expected to be good, therefore the first tool string, consisting of the MSS/HRLA/APS/HLDS/EDTC-B/HNGS tools, was rigged up with nuclear sources. The downlog proceeded without any incident to total depth. Repeat and main passes were carried out from total depth to 1085 and 490 m WRF respectively main pass was conducted from total depth to 485 m WRF. During the main pass the caliper was closed at about 630 m WRF in order to facilitate the re-entry into the drill pipe. Likewise the minitron source was switched off just after entering the drill pipe in order to ensure that no GR scattering would mask the sea floor signature on the main uplog. The second logging run consisted of a VSP experiment, which acquired 98 shots at 13 depths (stations).


The sea state was calm with an average peak-to-peak heave of 0.1 m. No Wireline Heave Compensator (WHC) was used.


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 (- 499.5 m). The sea floor depth was determined by the step in gamma ray values at 499.5 m WRF on the MSS/HRLA/APS/HLDS/EDTC-B/HNGS main pass. This corresponds to the sea floor depth given by the drillers (see above). The depth-shifted logs have then been 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 (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 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 P&S monopole, upper dipole, and Stoneley standard-frequency mode and in lower dipole low-frequency mode. The compressional and shear velocities were computed from the delay time and are generally of good quality. Processing of the sonic waveforms is recommended in order to get more accurate 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). In Hole U1467E repeatability among the three passes was good.


The gamma ray logs recorded through bottom hole assembly (BHA) and drill pipe should be used only qualitatively due to 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 caliper on the HLDS tool (LCAL) and the FMS tool (C1 and C2). Both calipers indicate a hole in good conditions for logging. They also show some evenly-spaced "artifacts" (washouts) in the 120-540 m WMSF interval. Because these mini washouts occur approximately every 9 m and only in the narrow part of the hole where the caliper possibly made good contact with the borehole wall, it is believed that they correspond to incisions made in the formation by the rotating thick drill pipe joints during the drilling. Furthermore, the fact that these washouts are visible on the calipers from two different tool strings would indicate that this is the most likely explanation.


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 359. 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