May 9-11 - Days 23-25 - Status Report

9-11 May  - Keathley Canyon 151 - Logging and Coring

Location: Keathley Canyon 151

Science Update - May 9-11:
May 9: The target depth of 459 mbsf at the the KC151#2 Logging While Drilling (LWD) hole was reached at about 2100 hrs. Logs show 85-m thick (215-300 mbsf) mudrock zone with several low resistivity or possible gas hydrate intervals. Only a small resistivity spike was noted at the depth of the seismic Bottom-Simulating Reflections(BSR) (385-393 mbsf).

Seismic line with position of BSR indicated

May 10: Drill pipe and logging tools were removed from KC151#2 LWD hole by 19:00 hrs. The sea bed frame and coring bottom hole assembly will be made up and lowered on the drill pipe to position on the sea floor for coring. Coring could begin by 19:00 hrs on 11 May at the earliest.

Additional results on the Atwater Valley pressure core degassing experiment were reported at the daily science meeting. The volume of methane obtained was 1.02L. Preliminary calculations suggest that this amount of methane would produce about 1% levels of gas hydrate saturation in the pore space, which is inadequate to explain inferred volume of low density material indicated by the core logging. Extruded sediment was sectioned and expressed pore waters analyzed. If the lower salinity pore water from the approximate location of the low density core material was due to fresh water dilution from gas hydrate decomposition, it suggests that gas hydrate saturation was on the order of 6% of pore space.

May 11: The first Fugro Hydraulic Piston Corer (FHPC) core from the KC151#3 borehole arrived on deck at 15:20 hrs. Cores 1H, 2H, 3H and 4H spanned the depth intervals 0-7.1, 9.4-17.2, 18.6-26.45, and 27.7-35.6 mbsf, respectively. Distinct H2S odors were present near the bottom of core 1H. The sulfate-methane interface appears to be at a depth of about 9 mbsf, or between cores 1H and 2H. Salinities increase from 35 ppt near the seafloor to about 40.5 ppt near the bottom of core 2H. The first temperature measurement was made at the bottom of core 3H, but the data has not yet been downloaded and interpreted.

Plans:
Reallocate planned coring intervals for KC151#3 hole to provide adequate coverage of possible gas hydrate zones.

The science party recommended a revised plan to focus coring in the intervals 0-45, 100-120, 210-295, 380-405, and 440-458 mbsf in hole KC151#3.

Continue coring down to a depth of about 45 mbsf, then wash down to a depth of 100 mbsf. Resume coring just above an unconformity capped by a 5-m thick water-bearing sand layer. Continue coring through and beneath the unconformity to a depth of about 120 mbsf, taking two pressure cores within this interval. Wash down to 200 mbsf and resume coring in the interval shown by LWD to be potentially gas hydrate-bearing.

Planning and Data Sheet for KC151 - #3   [PDF-10KB] 

Maps of drill sites - Shows Keathley Canyon and Atwater Valley locations

Special Report - core handling

Special Report - Conventional Wireline Logging Operations in the Gulf of Mexico Gas Hydrate JIP Drilling Program - Timothy Collett, USGS

Photos:
Day 16 Photo Gallery  - Photos by NETL scientist showing core analyses process and equipment
Day 13 Photo Gallery  - Photos by NETL scientist showing drilling preparation
Day 12 Photo Gallery  - Photos by NETL scientist showing core retrieval and processing
Day 10 Photo Gallery  - Pressurized core prior to transfer to lab and seabed frame preparation
Day 6 Photo Gallery - Working with push cores and ROV photos of sample collection at AT 14
Day 4 Photo Gallery - Remotely Operated Vehicle (ROV), Sampling, Core Handling
Day 3 Photo Gallery - Preparation for Drilling
Day 2 Photo Gallery Loading the Uncle John [PowerPoint]
The drill ship out to sea - Setting up the lab [PowerPoint]