IODP Expedition 395E

Complete South Atlantic Transect Reentry Installations

Daily Science Report for 30 April 2021

Location: Hole U1557D (30°56.4546′S, 26°37.7898′W, water depth 5010.66 mbsl, proposed Site SATL-56A)

Science Update: At the start of the day, we continued to make up the 14¾ inch drilling bottom-hole assembly (BHA). It was ready at 0230 h and we ran it down to 4980 m below sea level (mbsl) by 1100 h. We then deployed the subsea camera and conductivity-temperature-depth (CTD) instrument. From 1230 to 1430 h we slipped and cut drilling line as part of regular maintenance. We picked up the top drive and reentered Hole U1557D at 1600 h, retrieved the subsea camera and CTD instrument, and brought them back onboard at 1815 h. From 1830 to 1930 h we lowered the BHA into the cased part of the existing hole, taking weight at 60 m below sea floor (mbsf). From that depth we drilled down, making a 14¾ inch hole, and reached 135.7 mbsf at midnight.

Daily Science Report for 29 April 2021

Location: Hole U1557D (30°56.4546′S, 26°37.7898′W, water depth 5010.66 mbsl, proposed Site SATL-56A)

Science Update: The JOIDES Resolution arrived at Site U1557 (proposed Site SATL-56A) at 2130 h, after transiting the remaining 235 nmi of the total 502 nmi sea passage from Site U1560. The thrusters were lowered and the ship switched to dynamic-positioning (DP) mode at 2215 h. We then started to make up the 14¾ inch drilling bottom-hole assembly (BHA), which will be used to deepen Hole U1557D from the existing 16 inch casing depth (60 m below sea floor (mbsf)) down to 10 m into basement (~574 mbsf), in preparation for installing the next casing string.

Daily Science Report for 28 April 2021

Location: In transit to Site U1557 (proposed Site SATL-56A)

Science Update: The rig floor was secured for transit at 0045 h. We raised the thrusters and started the sea passage at 0124 h. The ship transited 267 nmi of the total 502 nmi transit to Site U1557 (proposed Site SATL-56A), which was first cored during Expedition 390C in November 2020.

COVID-19 safety protocols were lifted today because it has been 14 days since we left port.

Daily Science Report for 27 April 2021

Location: Hole U1560B (30°24.2057′S, 16°55.3702′W, water depth 3723.7 mbsl, proposed Site SATL-25A)

Science Update: We began the day disassembling the bit, underreamer, and mud motor that had been used to drill in the casing in Hole U1560B. We made up the bottom-hole assembly (BHA) for cementing, and lowered it to just above the seabed. The subsea camera was lowered to the BHA to guide reentry, and at 1445 h we reentered Hole U1560B. We positioned the base of the BHA at 3 m below seafloor (mbsf), which was deep enough for the cup packer in the BHA to seal the top of the casing. We established circulation and pumped 10 bbl of 15 ppg cement, and then pulled the BHA back out of the hole, clearing the reentry cone at 1545 h. The drill pipe was cleared of any residual cement by pumping down two pigs (pipe cleaning devices) and flushing with seawater. The subsea camera was raised back to the ship. From 1730 to 2315 h we raised the BHA back to the rig floor, ending operations at Hole U1560B. We then prepared the rig floor for transit.

The Expedition 390 and 393 (South Atlantic Transect I and II) Co-Chief Scientists, Expedition Project Managers, and Operations Superintendent met on 26 April to discuss how best to use the remaining operations time on Expedition 395E. We decided to defer operations at proposed Site SATL-33B, which was originally planned to be the second site of Expedition 395E. Instead, Site SATL-33B operations will take place during Expeditions 390/393. The next site of Expedition 395E will be Site U1557, where we will complete installation of the reentry system in Hole U1557D.

Carbonate and X-ray diffraction sample preparation and measurements on samples from Hole U1560A continue. COVID-19 safety procedures are in place.

Daily Science Report for 26 April 2021

Location: Hole U1560B (30°24.2057′S, 16°55.3702′W, water depth 3723.7 mbsl, proposed Site SATL-25A)

Science Update: We began the day by lowering the hydraulic release tool (HRT) stinger assembly through the water column, reaching 3675 m below sea level (mbsl) at 0130 h. We installed the top drive and deployed the subsea camera and conductivity-temperature-depth (CTD) instrument. We spudded Hole U1560B at 0430 h. A water depth of 3723.7 mbsl is assumed, based on the mudline depth at Hole U1560A. We drilled to the target depth of 124 m below seafloor (mbsf) and disconnected the casing using the HRT at 1025 h. We filled the cased hole with heavy mud to prevent inflow and raised the subsea camera and CTD to the ship. In the last activity of the day, we raised the stinger assembly to the ship, and the drill bit reached the rig floor at 2355 h.

Geochemical measurements on samples from Hole U1560A continue. COVID-19 safety procedures are in place.

Daily Science Report for 25 April 2021

Location: Hole U1560B (30°24.2064′S, 16°55.3718′W (preliminary), water depth 3723.7 mbsl, proposed Site SATL-25A)

Science Update: From midnight to 0700 h, we rigged up the 10¾ inch casing, picked it up with the running tool, and landed it on the base of the reentry cone in the moonpool. Then we rigged up the drill pipe stinger, including drill bit, underreamer, and motor, and tested it in the moonpool. By 1300 h we had lowered the stinger through the casing and secured it to the base. We constructed the reentry cone and welded it to the base, and at 1545 h we started lowering the whole assembly to the seafloor. Physical properties, imaging, and paleomagnetic measurements on cores from Hole U1560A are complete, and geochemical measurements continue. COVID-19 safety procedures are in place.

Daily Science Report for 24 April 2021

Location: Hole U1560A (30°24.2064′S, 16°55.3718′W, water depth 3723.7 mbsl, proposed Site SATL-25A)

Science Update: The final core from Hole U1560A, Core 16X, was brought on deck at 0505 h. Cores U1560A-15X and 16X advanced from 120.1 to 122.5 m below seafloor (mbsf) and recovered 0.44 m (18%). Upon recovery, these two cores were confirmed to be basement. The rate of penetration in this solid formation was slow (~0.6 m/h), so we stopped coring at this point. We raised the drill bit up to the ship, and it cleared the rig floor at 1520 h, ending Hole U1560A. The rest of the day was spent making up the hydraulic release running tool (HRT) bottom-hole assembly (BHA) in preparation for casing installation. Cores U1560A-1H to 13X were analyzed for physical properties on the track systems and were split. COVID-19 safety procedures continue to be followed.

Daily Science Report for 23 April 2021

Location: Hole U1560A (30°24.2064′S, 16°55.3718′W, water depth 3723.7 mbsl, proposed Site SATL-25A)

Science Update: We lowered the drill bit to 3708 mbsl and pumped two pigs (pipe cleaning devices) through the drill string to remove rust. The first advanced piston corer (APC) core was shot from 3714 mbsl but returned empty, missing the mudline. The drill bit was lowered 5 m for the next attempt. Mudline Core U1560A-1H arrived on deck at 0430 h and recovered 4.6 m, establishing a seafloor depth of 3723.7 mbsl. Cores U1560A-2H to 11H advanced from 4.6 to 99.7 m below seafloor (mbsf). Cores U1560A-1H to 11H recovered 101.55 m (102%). All APC cores were oriented with the core orientation tool (Icefield MI-5). Formation temperature measurements were taken on Cores 4H and 7H with the advanced piston corer temperature tool (APCT-3). At 1730 h we changed to the extended core barrel (XCB) coring system, because we were approaching the anticipated basement depth. Cores U1560A-12X to 14X advanced from 99.7 to 120.1 mbsf and recovered 17.09 m (84%). In total, Cores U1560A-1H to 14X recovered 118.64 m (99%). We ended the day coring Core U1560A-15X. A change of drilling rate at 120.2 mbsf indicated that the basement contact was reached at that depth.

Daily Science Report for 22 April 2021

Location: Site U1560 (30°24.2064′S, 16°55.3692′W, preliminary; proposed Site SATL-25A)

Science Update: The JOIDES Resolution arrived at Site U1560 (proposed Site SATL-25A) at 0108 h, after transiting the remaining 9 nmi of the total 1817 nmi transit from Cape Town. The thrusters were lowered and the ship switched to dynamic-positioning mode at 0215 h. The advanced piston corer/extended core barrel (APC/XCB) bottom-hole assembly was made up and deployed. By the end of the day we had lowered the drill bit to 3679 m below sea level (mbsl) and picked up the top drive, in preparation for coring at an expected seafloor depth of 3691 mbsl.

Daily Science Report for 21 April 2021

Location: In transit to Site U1560 (proposed Site SATL-25A)

Science Update: The ship transited 251 nmi, completing 1808 nmi of the total 1817 nmi transit to Site U1560 (proposed Site SATL-25A). JRSO staff and Siem Offshore crew prepared for coring and casing operations. COVID-19 safety procedures continue to be followed.

Daily Science Report for 20 April 2021

Location: In transit to Site U1560 (proposed Site SATL-25A)

Science Update: The ship transited 282 nmi, completing 1557 nmi of the total 1817 nmi transit to Site U1560 (proposed Site SATL-25A). The Co-Chief Scientists of South Atlantic Transect Expeditions 390 and 393 met with the Operations Superintendent and Expedition Project Managers to confirm operation priorities for Expedition 395E in the case of bad weather or insufficient time. The first core-on-deck is expected on the afternoon of 22 April. COVID-19 safety procedures continue to be followed.

Daily Science Report for 19 April 2021

Location: In transit to Site U1560 (proposed Site SATL-25A)

Science Update: The ship transited 274 nmi, completing 1275 nmi of the total 1817 nmi transit to Site U1560 (proposed Site SATL-25A). Estimated time of arrival at Site U1560 is early morning on 22 April. COVID-19 safety procedures continue to be followed.

Daily Science Report for 18 April 2021

Location: In transit to Site U1560 (proposed Site SATL-25A)

Science Update: The ship transited 280 nmi, completing 1001 nmi of the total 1817 nmi transit to Site U1560 (proposed Site SATL-25A). JRSO staff are finalizing sampling and measurement plans for Site U1560. COVID-19 safety procedures continue to be followed.

Daily Science Report for 17 April 2021

Location: In transit to Site U1560 (proposed Site SATL-25A)

Science Update: The ship transited 263 nmi, completing 721 nmi of the total 1817 nmi transit to Site U1560 (proposed Site SATL-25A). The ship’s clock was set back 1 h at 0200 h. COVID-19 safety procedures continue to be followed.

Daily Science Report for 16 April 2021

Location: In transit to Site U1560 (proposed Site SATL-25A)

Science Update: The ship transited 296 nmi, completing 458 nmi of the total 1817 nmi transit to Site U1560 (proposed Site SATL-25A). The ship’s clock was set back 1 h at 1400 h. COVID-19 safety procedures continue to be followed.

Daily Science Report for 15 April 2021

Location: In transit to Site SATL-25A

Science Update: In the morning, 14 Siem Offshore crew boarded the ship. The pilot boarded at 0922 h and the ship departed Cape Town, South Africa, at 1000 h. We completed 162 nmi of the total 1817 nmi transit to proposed Site SATL-25A. The transit is expected to take 7 d, arriving on 22 April. Siem Offshore and JRSO staff conducted two abandon ship drills, and continue to follow COVID-19 safety procedures.