Borehole Seismic Data

 

Science operator: Texas A&M University

Hole: U1500B

Expedition: 367

Location: China Sea Rifted Margin (South China Sea)

Latitude: 18° 18.2707' N

Longitude: 116° 13.1951' E

Logging date: April 6-7, 2017

Sea floor depth (driller's): 3812.8 m DRF

Sea floor depth (logger's): 3812.8 m WRF

Total penetration: 5341.8 m DRF (1529m DSF)

Total core recovered: 278.79 m ( 40.8 % of cored section)

Oldest sediment recovered: 16 Ma (Lower-mid Miocene)

Lithology: Sediments: clay, silt and sand; claystone/siltstone/sandstone. Igneous rocks: basalts.

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 367. 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 few stations were attempted in open hole but none of them yielded usable shots. One station was successful through the 10 3/4 in casing at 4596 m WRF (783.2 m WSF), where a compressional sonic curve recorded good coherency through the casing, thus indicating good conncetion with the formation. The 13 shots recorded were somehow noisy but at least 6 with similar transit times were stacked. They delivered a corrected transit time of 2.9386 sec, corresponding to the value expected by the shipboard party.

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 367.

For any question about the data or about the LogDB database, please contact LogDB support: logdb@ldeo.columbia.edu.