Borehole Seismic Data



Science operator: Texas A&M University

Hole: U1502B

Expedition: 368

Location: China Sea Rifted Margin (South China Sea)

Latitude: 18° 27.8798' N

Longitude: 116° 13.8409' E

Logging date: May 13, 2017

Sea floor depth (driller's): 3774.7 m DRF

Sea floor depth (logger's): 3774.7 m WRF

Total penetration: 4695.5 m DRF (920.8 m DSF)

Total core recovered: 303.75 m (52.7 % of cored section)

Oldest sediment recovered: Late Oligocene

Lithology:  Claystone, sand, clay


SEISMIC TOOL USED: VSI (Versatile Seismic Imager)


The logging data was recorded by Schlumberger in LDF/DLIS format. All processing, including first arrival picking and stacking, was performed by Schlumberger during Expedition . The data was then converted into SEGY format at LDEO, using code developed in house. Images of the VSP data in GIF format were created as well.

The tool string included the VSI and the EDTC-B, which was used for depth correlation with the other logging runs: a distinct peak at 4413 m WRF in the GR curve was used.A few stations were attempted in open hole but the tool appeared to be hanging up on a ledge and was unable to pass into the open-hole section. Eight stations were attempted through the 10 3/4 in casing but only six were successful (629, 589, 549, 450, 359, and 290). They delivered a corrected transit time of 2.9386 sec, corresponding to the value expected by the shipboard party.


The heave compensator was not required for any portion of the logging as the total heave was approximately 2 inches throughout the entire operating time.


Stacks are generally calculated with at least nine good traces.


All the data in the SEGY files are sorted shot by shot (i.e. chronologically).


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 368. 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


Gilles Guerin

phone: 845-365-8671

fax: 845-365-3182

E-mail: Gilles Guerin