Twelve holes were drilled at this site (Table T1), under good weather conditions. Wind speed was 0-8 kt, gusting to 12 kt; seas were 0-4 ft; swell was 4-7 ft; and the prevailing sea-surface current was from the north at ~0.5 kt. LWD data were collected from Hole 1249A on 21 July 2002. We returned to this site on 24-26 July for LWD operations in Hole 1249B using the new RAB-8 coring system and to core Hole 1249C to 89.5 mbsf with the APC. We returned to this site again on 4-6 August to core Holes 1249D-1249F. Near the end of the leg, we occupied this site one last time on 27-29 August to core Holes 1249G-1249L with the APC/XCB for a shore-based hydrate geriatrics study. During this last visit, wind speed had increased to 14-19 kt, gusting to 23 kt; seas were 6-7 ft; and swell was 8-10 ft.
All pressure coring systems available were used at Site 1249. The ODP pressure core sampler (PCS) was deployed a total of six times, and the Fugro Pressure Corer (FPC) and HYACINTH Hydrate Autoclave Coring Equipment (HYACE) Rotary Corer (HRC) were each deployed three times at this site. Eleven in situ temperature runs were made at this site: nine using the APC temperature (APCT) tool and two using the Davis-Villinger Temperature-Pressure Probe (DVTPP). Pressure data were measured using the DVTPP.
The Mauna Loa came alongside on 25 July and was secured on the starboard side at 0605 hr to transfer freight and personnel to the Joides Resolution. Personnel included HYACINTH FPC engineers Floris Tuynder and Roeland Baas, logging scientist Gilles Guérin, Dallas Morning News journalist Alexandra Witze, paleontologist Mahito Watanabe, and HRC engineer Felix Weise. A linear X-ray scanner (LXS) from Lawrence Berkley National Laboratory (Freifeld et al., in press, 2002) was installed in the core laboratory, and training of personnel was conducted. In addition, the TAMU logistics coordinator, a LXS scientist, and a LXS student technician/programmer came on board for the day. Off-going personnel included logging scientists Nathan Bangs and David Goldberg, LWD engineers Stefan Mrozewski and Khaled Moudjeber, and geophysisist Marteen Vanneste. LWD tools were loaded, and the Mauna Loa departed for Coos Bay, Oregon, at 1715 hr.
On 6 August, a helicopter arrived on deck at 1227 hr with passengers Bill Gwilliam from Department of Energy (DOE)/National Energy Technology Laboratory (NETL), Dean Ferrell, electrical technician from the Ocean Drilling Program (ODP)/Texas A&M University (TAMU), and Transocean 3rd engineer Yorn Verschoor. The helicopter departed at 1243 hr carrying passengers Alexandra Witze, a journalist from the Dallas Morning News, and John Beck, ODP/TAMU photographer.
The final rendevous of the leg took place on 27 August, when the Mauna Loa tied up along port side at 0650 hr. We loaded crates for packing the off-going Vertical Seismic Imager (VSI)/Schlumberger equipment, DOE pressure vessels/sample dewars, liquid nitrogen dewars, and equipment for the German film crew (CONTEXT-TV). Schlumberger downhole tools/pallets and off-going samples were off-loaded. Passengers joining the JOIDES Resolution included Jan Hartmann and Stephan Braun from German CONTEXT-TV and Randy Showstack, Eos journalist. The Mauna Loa released at 0900 hr to transfer personnel and equipment to and from the Ewing. The Mauna Loa returned alongside the JOIDES Resolution at 1100 hr and off-loaded the remaining Schlumberger VSI surface equipment. Passengers departing the JOIDES Resolution included Alexei Milkov, sedimentologist, and Herbert Leyton, Schlumberger VSP engineer. The Mauna Loa departed at 1130 hr.
Hole 1249A was spudded at 0900 hr on 21 July to conduct LWD measurements using the same tools as were used at the other sites during this leg. Drilling proceeded at reduced rates of penetration (ROPs) of 15 m/hr and 15 strokes per minute (spm) circulation to moderate formation washout at shallow depths below seafloor. No real-time measurement-while-drilling (MWD) or nuclear magnetic resonance (NMR) data were recorded over this interval. The ROP was increased to 25 m/hr from a bit depth of 30 mbsf to a total depth (TD) of 90 mbsf, and real-time MWD and NMR data were recorded (see "Downhole Tools and Pressure Coring"). The LWD tools were pulled to ~60 m above the seafloor at 1600 hr on 21 July. Total bit run took ~7 hr.
Hole 1249B was drilled using the new LWD RAB-8 and coring system, which permits simultaneous acquisition of core and logging data. LWD operations began with initialization of the RAB-8 at 1315 hr on 24 July. Although exercised fully in Houston, Texas, the inner mandrel in the RAB-8 BHA was too high to make up with the 65/8-in pin above. The inner diameter of the pin was ground down, and the motor-driven core barrel (MDCB) was tested until it passed through. Hole 1249B was finally spudded at 2000 hr. Drilling proceeded ahead to 30 mbsf, and coring operations began with sequential 4.5- and 9-m cores recovered through hydrate-bearing clays to a TD of 74.9 mbsf. Bit rotation varied from 15 to 45 rpm, increasing with depth, and the average ROP using this system was ~8 m/hr. The RAB-8 was recovered at the rig floor at 1200 hr on 25 July, and the data recorded in computer memory were downloaded. Total testing time was ~22 hr.
The recorded RAB data from Hole 1249B are of good quality over the drilled interval and correlate well with the log curves in Hole 1249A (see "Downhole Logging"). The eight rotary cores recovered from Hole 1249B had an average of 32.9% recovery. These test cores were normally processed and archived and will be correlated to the RAB logs over the same depth interval. RAB-8 images and logs are of high quality but require additional depth correction to account for the coring process (see "Downhole Logging"). With harder formations and faster rotary coring, both core recovery and log data quality are expected to improve using the RAB-8 coring system.
This successful test marks the first ever logging-while-coring experiment, a new technology that allows for precise core-log depth calibration and core orientation within a single borehole and without a pipe trip. It represents an outstanding example of a successful cooperative effort between Lamont-Doherty Earth Observatory (LDEO) and TAMU to develop and validate the logging-while-coring concept.
Holes 1249C-1249F recovered a 90-m sediment sequence with the APC (Table T1). Core recoveries were <30% in the uppermost 20 mbsf and increased to 70% deeper in the holes. All pressure coring devices were used to sample this sediment sequence in an effort to capture massive hydrate samples under pressure and to compare the capabilities of each of these tools in sampling gas hydrates (see Table T2 in the "Leg 204 Summary" chapter). The PCS was deployed six times in these holes, but only three cores were recovered under pressure. Two deployments of the FPC at 8 mbsf did not recover core at in situ pressures. A deployment of the HRC at 8 mbsf in Hole 1249F resulted in successful recovery of core under full pressure, which was rapidly cooled in the ice bath to maintain stability, successfully sheared, and transferred into the HYACINTH logging chamber. It was subsequently logged repeatedly in the Geotek Vertical Multi Sensor Core Logger (V-MSCL) while being degassed over the following 2 days (see "Downhole Tools and Pressure Coring").
Temperature measurements were collected during six runs of the APCT tool (one in Hole 1249C and five in Hole 1249F) and two runs of the DVTPP (one in each of Holes 1249C and 1249F). Whirl-Paks and perfluorocarbon tracer (PFT) were used for microbiology cores in Holes 1249D-1249F (see Table T3 in the "Leg 204 Summary" chapter), and the Drill String Acceleration (DSA) tool was run in Holes 1249C (once) and 1249F (twice).
Holes 1249G-1249L were APC/XCB cored for a special shore-based geriatrics experiment in which several means of preserving gas hydrates for future study will be compared. Of the 40 steel pressure vessels that were taken on board, 34 were repressurized with core samples. The total quantity of core preserved in pressure vessels is ~50 m of sediment. The pressure being maintained in each of these vessels is nominally 550-600 psi at 4°-6°C. The remaining ~35 m of core recovered was placed into labeled cloth bags and is preserved in liquid nitrogen cryofreezers. Both the pressure vessels and the cryofreezers were stored in a refrigerated container van aft of the drill floor on the core tech shop roof. We conducted systematic periodic monitoring of the ambient air inside the container van by taking samples and running them through the shipboard gas chromatograph. We also monitored the gas pressures in each of the pressure vessels, the levels of the liquid nitrogen in the cryofreezers, and the temperature in the containers.
Two pressure vessels originally filled and repressurized with sediment containing significant quantities of hydrogen sulfide were taken out of service because of the risk of steel metal fatigue as a result of contact with hydrogen sulfide. In addition, two pressure vessels failed to maintain pressure because of leaks in valve or gauge connections; some of the hardware from these vessels was used to replace faulty gauges on other pressure vessels. Two additional pressure vessels were not used because of the termination of coring. These are available for future studies and for use as "standards" to make gamma ray attentuation (GRA) density measurements.
The Transocean drillers, core technicians, and rig crew did a superb job of handing the cores recovered on deck and transferring them to the ODP Marine Laboratory Technicians and ODP Shipboard Curator for processing on the catwalk. All the personnel involved were extremely fast, efficient, and professional in their handling of these hydrated cores in a way to maximize core preservation and ensure core quality. The safe handling of the pressure vessels, their repressurization, and the resulting preservation of the cores contained inside was successfully carried out in a short space of time immediately following the arrival of a large amount of equipment transported to the JOIDES Resolution by supply boat.
In addition to the APC/XCB cores for the geriatrics study, there were three deployments of pressure coring devices in these holes (Table T17). The HRC deployment at 13.5 mbsf in Hole 1249G successfully recovered a 75-cm core with massive hydrate layers at full pressure and transferred this material into a HYACINTH storage chamber (see "Downhole Logging"). It was subsequently frozen in He under pressure and successfully transferred into liquid nitrogen for preservation. It is probably the most pristine sample of natural gas hydrate ever recovered and preserved.
The FPC was also deployed at 13.5 mbsf in Hole 1249G and recovered 75 cm of core at full pressure. A good GRA density log was obtained from the core in the storage chamber showing massive hydrate layers (see "Downhole Logging"). This core was designated as a "reference core" and companion to the APC and XCB cores that were taken and repressurized under methane. It was kept in the refrigerator ready for transportation to Texas A&M University for further study.
The HRC was deployed again, deeper in the sediments in Hole 1249L (37.5 mbsf), in an attempt to recover pristine material under pressure from a region where the hydrate is more disseminated. Some pressure was lost during disassembly, but it was rapidly repressurized to in situ pressures before being transferred to the logging chamber.
Temperature measurements were collected with one APCT tool run in each of Holes 1249G, 1249I, and 1249L (Table T15).