Earth Institute News
Contact: Mary Tobin
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Reports From the Field
IODP Expedition 301: Drilling for Clues in the Juan de Fuca Ridge
While the volume of water flow through the mid-ocean ridge is believed to be the same magnitude as the water entering the oceans from all the world's rivers, virtually nothing is known about the chemicals and bacteria it contains, or how this system works. Many scientists believe that Earth’s first organisms may have originated at locations like the Juan de Fuca Ridge. The scientific drillship JOIDES Resolution left Astoria, Oregon on June 27, 2004 for a two-month drilling expedition on the east ridge of the Juan de Fuca Ridge (known as IODP Expedition 301) to capture sample fluids that may contain new microbes and sediment that will help scientists better understand this system. This expedition marks the beginning of the Integrated Ocean Drilling Program (IODP), a joint drilling project between the U.S. National Science Foundation (NSF) and the Alliance of the Joint Oceanographic Institutions, Inc., Texas A&M University, and Lamont-Doherty Earth Observatory of Columbia University.
IODP traces its origin back to the late 1960’s when it was named the Deep Sea Drilling Project (DSDP) and later becoming the Ocean Drilling Program (ODP). (read more background on the project. )
Dr. Gerardo J. Iturrino, a research scientist at the Lamont-Doherty Earth Observatory, is working on IODP Expedition 301 as the Logging Staff Scientist in charge of wireline logging operations. He is also serving as a mentor to the first IODP Teacher at Sea, Jonathan Rice, Ph.D., an 8th grade teacher from Green Mountain Union High School in Vermont. Rice writes a daily journal about his experiences at sea during this expedition and laboratory briefs that will be used as educational materials for students and other teachers.
During this expedition, two new holes will be drilled and long-term observatories will be installed. Each long-term observatory, also known as Circulation Obviation Retrofit Kit, or CORK, will be able to measure permeability, temperature and pressure conditions for up to five years and will sample formation fluids for geochemistry and microbiology studies. Scientists will also replace two CORK installations. The new CORK instrumentation will allow for more diverse studies of hydrothermal environments and will be one of the primary objectives for subsequent cross-hole experiments.
July 11, 2004
We began drilling operations at the second ridge with the intentions of drilling two holes and installing a CORK in each of the boreholes. The operational plans began with a jet-in test to determine the hardness of the sediment cover and the length of the 20” casing that would be attached to the re-entry cone. The installation of the reentry cone and 20” casing to about 39 mbsf (meters below sea floor) went well and we quickly started assembling a 18.5” pilot bit and underreamer that was going to be used for opening the hole for the next casing string. We only drilled down with the underreamer and pilot bit until the sediments got too hard this system is not designed for hard formations. At this point, we tripped the pipe to replace the underreamer with a bicenter bit that was better suited for the task of drilling through hard formations. The entire opening of the hole (with both the underreamer and bicenter bit) took approximately 3 days.
The bicenter bit worked well, and we reached the target depth of about 271 mbsf. After circulating a mud pill (about 20 barrels of mud) to help clean cuttings out of the hole, a wiper trip was conducted (raising the bit up and down in the newly drilled portion of the hole to make sure the walls of the hole are stable). Then a 16” casing string was assembled and deployed followed by similar procedures to install 10-3/4” casing in a newly drilled 14-3/4” section of the hole. The 14-3/4” hole reached 107.1 m into basement or 369.5 mbsf; however, a wiper trip before pulling out of the hole indicated the presence of an interval of rapid drilling penetration rate that would be the cause of some trouble ahead of us.
We reentered one of the holes (Hole 1301A) with a 360.4 m-long string of 10-3/4 inch casing (about 98.4 m into basement) until about 4m above where the casing hanger would land in the reentry cone. After we halted circulating to install the cementing manifold before landing the casing, we could not lower the casing. We suspected that rocks falling out of the fast drilling interval were causing the problems and after several attempts to lower the casing, we decided to recover the casing string. An attempt to deploy a shorter casing string (273.3 m-long) was then successful and we therefore made Hole 1301A the shallow basement-monitoring hole.
We are currently drilling and casing Hole 1301B (47° 45.2276‘ N, 127° 45.8269’ W; water depth: 2666.5 mbrf (meters below rig floor)) with the intentions of making this location the deep basement monitoring hole. We have successfully deployed 20” and 16” casing strings to 268.5 mbsf (2 m into basement) and we will continue drilling until the 10-3/4” casing is in place. Coring and logging operations will then follow prior to the CORK installations.