Drilling-induced and logging-related features illustrated from IODP–ICDP Expedition 364 downhole logs and borehole imaging tools

Abstract

Expedition 364 was a joint IODP and ICDP mission-specific platform (MSP) expedition to explore the Chicxulub impact crater buried below the surface of the Yucatán continental shelf seafloor. In April and May 2016, this expedition drilled a single borehole at Site M0077 into the crater's peak ring. Excellent quality cores were recovered from ∼ 505 to ∼ 1335 m below seafloor (m b.s.f.), and high-resolution open hole logs were acquired between the surface and total drill depth. Downhole logs are used to image the borehole wall, measure the physical properties of rocks that surround the borehole, and assess borehole quality during drilling and coring operations. When making geological interpretations of downhole logs, it is essential to be able to distinguish between features that are geological and those that are operation-related. During Expedition 364 some drilling-induced and logging-related features were observed and include the following: effects caused by the presence of casing and metal debris in the hole, logging-tool eccentering, drilling-induced corkscrew shape of the hole, possible re-magnetization of low-coercivity grains within sedimentary rocks, markings on the borehole wall, and drilling-induced changes in the borehole diameter and trajectory.Published by Copernicus Publications on behalf of the IODP and the ICDP. J. Lofi et al.: Expedition 364 downhole logging 375 m DSF: artesian water flow up pipe when pipe unhooked from drill head 15.5 m DSF 503.6 m DSF 701.7 m DSF 1334.69 m DSF Cased 9 5/8" (24.45 cm)

Multiscale Geoelectrical Properties of the Rochechouart Impact Structure, France

“…On the other hand, the IMR from the M0077 drilling site of the IODP-ICDP Exp 364 within the peak ring of the Chicxulub impact structure (Mexico; Morgan et al, 2016) show extremely low electrical resistivity values considering either multiscanner core logging data (0.4-3.4 Ohm.m) or downhole logging data using EM51 induction tool (3-6 Ohm.m; Gulick et al, 2017;Lofi et al, 2018;Morgan et al, 2017). The large porosities (about 20%) of the Chicxulub IMR units and their saturation in saline water largely decrease their initial electrical resistivity.…”

Borehole Seismic Observations From the Chicxulub Impact Drilling: Implications for Seismic Reflectivity and Impact Damage

“…Site M0077 (Figure 1c) was drilled during the joint IODP/ICDP Expedition 364 campaign in 2016 at a location estimated to be ∼46 km from the center of the impact structure. Summaries of the technical details of the project may be found in (Gulick et al., 2017a), of the geophysical logging in (Lofi et al., 2018), and of the combined log/core property interpretation in (Christeson et al., 2018; See Table S1 in Supporting Information ). The borehole was drilled in three stages, dependent upon engineering and key target considerations, with cores obtained between 505.7 and the total depth of the hole at 1334.7 m below sea floor (mbsf; Morgan et al., 2017).…”