Design, Manufacture, and Operation of a Core Barrel for the Iceland Deep Drilling Project (IDDP)

Abstract

The science program of the Iceland Deep Drilling Project (IDDP) requires as much core as possible in the transition zone to supercritical and inside the supercritical zone (>374°C), in the depth interval 2400-4500 m. The spot coring system selected has a 7 ¼ " (184.15 mm) OD at 10 m length and collects a 4 " (101.6 mm) diameter core using an 8 ½ " (215.9 mm) OD core bit. It incorporates design characteristics, materials, clearances and bearings compatible with operation of the core barrel at temperatures as high as 600°C. Special attention was given to the volume of flushing which could be applied to the core barrel and through the bit while running in and out of the borehole and while coring. In November 2008 a successful spot coring test using the new core barrel was performed at 2800 m depth in the production well RN-17 B at Reykjanes, Iceland, where the formation temperature is 322°C. A 9.3-m hydrothermally altered hyaloclastite breccia was cored with 100% core recovery, in spite of it being highly fractured. A core tube data logger was also designed and placed inside the inner barrel to monitor the effectiveness of cooling. The temperature could be maintained at 100°C while coring, but it reached 170°C for a very short period while tripping in. The effective cooling is attributed to the high flush design and a top drive being employed, which allows circulation while tripping in or out, except for the very short time when a new drill pipe connection is being made.

The Iceland Deep Drilling Project 4.5 km deep well, IDDP-2, in the seawater-recharged Reykjanes geothermal field in SW Iceland has successfully reached its supercritical target

“…We were using an IDDPdesigned 8 1 2 coring tool, with 9.7 m long core barrel (Skinner et al, 2010), which had yielded good core recoveries in RN-17B, an inclined 8 1 2 hole from 2800 m depth, and also from three successive core runs below a 9 RN-30 at Reykjanes from similar depth to RN-17B (Fowler et al, 2015;Fowler and Zierenberg, 2016). Table 2 gives an overview of the core recovery in 10 core runs with the IDDP 8 1 2 coring tool and 3 successive core runs with the 6 Baker Hughes tool at the bottom of IDDP-2, beneath the 7 liner.…”

Elemental changes and alteration recorded by basaltic drill core samples recovered from in situ temperatures up to 345°C in the active, seawater‐recharged Reykjanes geothermal system, Iceland

“…The core apparently jammed in the core barrel when it broke along a high‐angle chlorite‐actinolite lined fracture at the base of the recovered core [ Friðleifsson and Richter , ]. The RN‐17B and RN‐30 cores were obtained using a core‐bit and core barrels specially designed for scientific drilling into extreme high‐temperature conditions [ Skinner et al ., ].…”

The MoHole: A Crustal Journey and Mantle Quest, Workshop in Kanazawa, Japan, 3–5 June 2010

“…These were presented at the workshop by industry representatives. Conversely, some of the required technologies are very specific to scientific drilling, such as logging and coring at high temperatures (e.g., the IDDP project, Skinner et al, 2010) or drilling the hard crustal and mantle rocks. Development of such technologies will be a primary key for success, but to achieve this it may be necessary to complement IODP financial support with external funding.…”