LEG 174B
CORK Hole 395A/Offset Drilling Engineering
CORK Leg Section Modified from Proposal 424 Submitted By
K. Becker and E. Davis
Engineering Leg Section Proposed by Tom Pettigrew
Staff Scientist: Mitch Malone
Co-Chief Scientist: Keir Becker
Abstract
Leg 174B is a two-part leg. The first half of the leg will perform downhole experiments and then CORK Hole 395A located in the Mid-Atlantic Ocean. The second half of the leg will perform field tests on the hammer drill-in casing system at the Mid-Atlantic Ridge at the Kane Transform. The primary purpose of the CORK experiments at Hole 395A is to monitor how the hydrologic system varies with time as natural hydrogeological conditions are re established after sealing the hole. Returning to the natural thermal regime will allow us to determine if the downhole flow observed at this site is dynamically maintained due to active circulation occurring in the basement, with or without the presence of a borehole, or due to flow induced by the geothermal gradient. The downhole experiements will provide essential information about the formation pressure and permeability structure to understand the crustal hydrogeology of the active off-axis hydrologic system at Hole 395A. The purpose of testing the hammer drill-in casing system is to determine the viability of the hammer drill, as well as the complete casing system, and determine the maximum slope that can be spudded by the tool.