JA Daily Science Report for Expedition 309, 12 August 2005
LOCATION: Site 1256
SCIENCE UPDATE: The pipe was tripped to inspect the BHA for possible cracks after the driller identified a 350 psi pump pressure loss following recovery of Core 146R. The BHA was at the rotary table at 2300 on 11 August and the drill collars were inspected using the magnaflux until 0415 12 August but no cracks were found. A crossover sub, tapered drill collar, and one stand of 5-1/2 transition pipe were laid out and replaced due to wear. A new CC-9 bit (#8) was made up and a core barrel was dropped so that drill-stand pressures could be checked as the pipe was lowered. The drill string was filled with seawater every 25 stands and the pressure checked. Pump pressure increases were noted at 25 and 50 stands but because there was no further pressure increases with 75 and 100 stands deployed, a crack in the drill string was suspected. The VIT sled was lowered and a high-viscosity mud pill displaced to try to locate any breaches in the drill string. As the VIT was lowered towards the BHA, a vigorous jet of drilling mud was observed streaming from the 5 pipe one stand above the 5-1/2 transition pipe. The drill string was pulled back up to the rig floor. This time the bottom two stands of 5 drill pipe were replaced. Hole 1256D was successfully reentered for the ninth time at 0230 13 August and coring was resumed.
Once again, careful monitoring of drilling conditions and exhaustive diagnosis work by the JOIDES Resolution operations team has averted a major drill string failure and loss of equipment in Hole 1256D.