27. Data Report: Nuclear Magnetic Resonance Logging while Drilling ODP Leg 204Timothy S. Collett, Myung W. Lee, David S. Goldberg, Frank R. Rack, and Trevor WilliamsABSTRACTINTRODUCTIONLeg 204 OperationsLWD ProgramMETHODSNuclear Magnetic Resonance LoggingNMR Logging FundamentalsNMR Log QualityLWD Data ProcessingDATA AND RESULTSLeg 204 Well Logging Data AccessNMR Properties of Gas HydrateNMR Log-Derived PorositiesNMR Logging-Derived Gas Hydrate SaturationsSUMMARYACKNOWLEDGMENTSREFERENCESFIGURES: ThumbnailF1. Map of Hydrate Ridge, p. 11.F2. LWD drill configuration on Leg 204, p. 12.F3. Schlumberger proVision tool, p. 13.F4. NMR T2 for a typical sediment, p. 14.F5. ProVision- and core-derived porosity, p. 15.F6. Porosities and derived gas hydrate saturations, p. 17.FIGURES: Full pageFigure F1. Map of sites cored and logged during Leg 204 on Hydrate Ridge.Figure F2. Configuration of the drill string used for LWD operations on ODP Leg 204. VDN = Vision Density Neutron tool. MWD = measurement-while-drilling tool. GVR = GeoVision resistivity-at-the-bit tool.Figure F3. Schematic illustration of the Schlumberger proVision NMR-While-Drilling tool.Figure F4. NMR transverse magnetization relaxation times (T2) for a typical sediment containing gas hydrate and/or water (depicted as a fluid induction decay signal). FFI = free-fluid index.Figure F5. A. ProVision- and core-derived porosity from four of nine holes drilled on Hydrate Ridge during Leg 204 (Holes 1244D, 1245A, 1246A, and 1247A). NMR = nuclear magnetic resonance. (Continued on next page.)Figure F5 (continued). B. ProVision- and core-derived porosity from five of nine holes drilled on Hydrate Ridge during Leg 204 (Holes 1248A, 1249A, 1250A, 1250B, and 1251A). NMR = nuclear magnetic resonance.Figures F6. A-I. ProVision- and density log-derived porosities and derived gas hydrate (GH) saturations (shown as concentrations...TABLE: ThumbnailT1. Leg 204 holes surveyed with LWD and MWD tools, p. 22.TABLE: Full pageTable T1. List of ODP Leg 204 sites and holes surveyed with logging-while-drilling and measurement-while-drilling tools.Tréhu, A.M., Bohrmann, G., Torres, M.E., and Colwell, F.S. (Eds.)Proceedings of the Ocean Drilling Program, Scientific Results Volume 20427. DATA REPORT: NUCLEAR MAGNETIC RESONANCE LOGGING WHILE DRILLING, ODP LEG 2041Timothy S. Collett,2 Myung W. Lee,2 David S. Goldberg,3 Frank R. Rack,4 and Trevor Williams3ABSTRACTMost published gas hydrate volumetric estimates have of necessitybeen made by broad extrapolation based on only general knowledge oflocal geologic conditions. The amount of gas that might be stored in agas hydrate accumulation is dependent on a number of reservoir pa-rameters, including the areal extent and thickness of the gas hydrate oc-currence, sediment porosities, and the degree of gas hydrate saturation.Downhole logs often serve as a source of critical gas hydrate reservoirdata. Before Ocean Drilling Program (ODP) Leg 204, however, onlyabout seven gas hydrate occurrences had been sampled and surveyedwith open hole well logging devices. From 16 July through 25 July2002, a complex logging-while-drilling (LWD) and measurement-while-drilling program was conducted on Hydrate Ridge during ODP Leg 204.During the cruise, and for the first time during ODP, the LWD toolstring included Schlumberger’s Nuclear Magnetic Resonance WhileDrilling tool (proVision).Postcruise research with the proVision data has consisted of estimat-ing bound fluid volumes and total fluid porosities, along with compar-ing nuclear magnetic resonance (NMR)-derived porosities with thosederived from downhole measured neutron and density logs and coremeasurements. These efforts have focused on calculating gas hydrateconcentrations by indirect methods using NMR data. It has been shownthat it is possible to obtain gas hydrate saturations (percent of porespace occupied by gas hydrate) from downhole logging–measured NMRporosities. In this study, porosities derived from the NMR proVision1Collett, T.S., Lee, M.W., Goldberg, D.S., Rack, F.R., and Williams, T., 2006. Data report: nuclear magnetic resonance logging while drilling, ODP Leg 204. In Tréhu, A.M., Bohrmann, G., Torres, M.E., and Colwell, F.S. (Eds.), Proc. ODP, Sci. Results, 204: College Station, TX (Ocean Drilling Program), 1–22. doi:10.2973/odp.proc.sr.204.106.20062U.S. Geological Survey, Denver Federal Center, Denver CO 80225, USA. [email protected] Research Group, Lamont-Doherty Earth Observatory of Columbia University, Palisades NY 10964, USA.4Joint Oceanographic Institutions, Inc., 1755 Massachusetts Avenue Northwest, Suite 700, Washington DC 20036, USA. Present address: ANDRILL Science Management Office, University of Nebraska-Lincoln, 126 Bessey Hall, Lincoln NE 68588-0341, USA.Initial receipt: 14 January 2005Acceptance: 24 July 2005Web publication: 17 October 2006Ms 204SR-106T.S. COLLETT ET AL.DATA REPORT: NMR LOGGING WHILE DRILLING 2tool were used along with porosity data from the Azimuthal VisionDensity Neutron tool to calculate gas hydrate saturations at all nineLWD logging sites on Hydrate Ridge. The NMR-density-porosity rela-tion yielded gas hydrate saturations ranging from high values near thecrest of the ridge of ~50% and higher in Hole 1249A to much lower val-ues along the flanks of the ridge.INTRODUCTIONLeg 204 OperationsOne of the primary goals of Ocean Drilling Program (ODP) Leg 204was to determine the distribution and concentration of gas hydrates be-neath Hydrate Ridge, which is located ~90 km off the coast of Oregon(USA). After coring the first site (Site 1244), logging-while-drilling(LWD) data were acquired from an additional 10 holes at 8 respectivesites (Table T1). The LWD data confirmed the general position of keyseismic stratigraphic horizons and yielded estimates of gas hydrate con-centrations through various downhole logging proxies. These recordsproved to be of great value in planning subsequent coring. After com-pleting the 10-day LWD program, the LWD tools were removed fromthe ship by an open-ocean small boat transfer. The remaining portionof the cruise dealt with coring more than 45 holes at 9 sites on HydrateRidge. Eight of these sites were the same sites that were already drilledand logged during the LWD program. The Hydrate Ridge coring pro-gram also included acquisition of conventional wireline logs from anadditional six holes.LWD ProgramThe downhole logging program during Leg 204 was specifically de-signed to obtain the data