Six holes were drilled at Site 1250 (Table T1), under good weather conditions. Wind speed was 0-11 kt, gusting to 16 kt; seas were 0-4 ft; swell was 4-8 ft and the prevailing sea-surface current was from the north at ~0.5 kt. Holes 1245A and 1250B were drilled without coring on 21-22 July 2002 to obtain the initial LWD data for this site. We returned to this site on 2-4 August to core Holes 1250B through 1250E and again on 24-27 August to core Hole 1250F (Table T1).
Hole 1250A was spudded at 1830 hr on 21 July to obtain the initial LWD data for this site (see "Downhole Tools and Pressure Coring"). Drilling proceeded at reduced rates of penetration (ROPs) of 15 m/hr and 15 strokes per minute (spm) circulation to moderate formation washout below seafloor. No real-time measurement-while-drilling (MWD) or nuclear magnetic resonance (NMR) data were recorded over this interval. The penetration rate was increased to 25 m/hr at a bit depth of 30 mbsf to a total depth (TD) of 210 mbsf, and real-time MWD and NMR data were acquired. The LWD tools were pulled to the rig floor at 1415 hr on 22 July for a total bit run of ~21 hr, at which time we noted that recording of the RAB tool had failed because of depleted batteries; the LWD operation was repeated in Hole 1250B.
Hole 1250B was spudded at 1400 hr on 23 July, after waiting for the Sonne to finish instrument deployment at this site. Drilling proceeded at a moderate ROP of 25 m/hr and 15 spm circulation to 20 mbsf. No real-time MWD or NMR data were recorded over this interval. The ROP was increased to 50 m/hr and maintained to a TD of 180 mbsf. The pipe was pulled up from the bottom of the hole (BOH) to ~160 mbsf without rotating to evaluate the effect of drilling motion on the NMR log (see "Downhole Tools and Pressure Coring"). The tools were recovered at the rig floor at 0600 hr on 23 July.
Holes 1250C and 1250D were APC/XCB cored down to 148 and 147 mbsf, respectively, with average core recoveries of 82% of the total penetration. Because of the high levels of higher hydrocarbons encountered near Horizon A at Site 1248, we decided to terminate drilling in Holes 1250C and 1250C at depths shallower than 150 mbsf. Further penetration was delayed until a better understanding of potential hazards associated with drilling through this horizon were evaluated by drilling further downdip.
Special tools were used for temperature measurements in Hole 1250C, including five APCT tool and two DVTPP runs. Temperature measurements in Hole 1250D included four APCT tool and two DVTPP runs (Table T15).
The PCS was deployed two times in Hole 1250C and three times in Hole 1250D (Table T16). Two deployments of HYACINTH tools were made, one with the FPC in Hole 1249C and one with the HRC in Hole 1249D. A good core was recovered with the FPC, but full retraction into the autoclave was prevented as a result of inadvertent line tension during the coring operation. The HRC, on the other hand, recovered a short core at full in situ pressure, which was then transferred under full pressure and logged in the Vertical Multi Sensor Core Logger (V-MSCL) before being depressurized. Unfortunately, the Drill String Acceleration (DSA) tool was still plagued by technical difficulties and failed to provide any useful downhole data (see "Downhole Tools and Pressure Coring")
Hole 1250E, which comprises two cores with 92% core recovery, was drilled to 16 mbsf for special biogeochemistry sampling. No special tools were run in this hole, but Whirl-Paks and perfluorocarbon tracer (PFT) were used for each of these cores (see Table T3 in the "Leg 204 Summary" chapter).
Hole 1250F was APC/XCB cored from 100 to 182 mbsf on 24-27 August to extend the depth of sampling after coring Horizon A at Sites 1245 and 1247. The PCS was deployed three times in Hole 1250F (Table T16). There were no deployments of the HYACINTH tools, nor were temperature measurements conducted in this hole.
Wireline logging was performed in Hole 1250F using separate runs of the triple combination (triple combo) (Temperature/Acceleration/Pressure [TAP] tool/Dual Induction Tool [DIT]/Hostile Environment Litho-Density Tool [HLDT]/Accelerator Porosity Sonde [APS]/Hostile Environment Gamma Ray Sonde [HNGS]/Inline Checkshot Tool [QSST]) and the Formation MicroScanner (FMS)-sonic (FMS/Dipole Sonic Imager [DSI]/Scintillation Gamma Ray Tool [SGT]) tool strings down to 180 mbsf (see "Downhole Logging"). Vertical and offset vertical seismic profiles (VSPs) were acquired with the JOIDES Resolution and the Ewing (located at an offset of ~700 m) alternating shots. This was followed by walkaway VSPs shot by the Ewing to downhole seismometers clamped at 91, 138, and 172 mbsf.