Grain Size Constraint on Gas Hydrate Occurrence: Evidence from Sediment Size during IODP 311
Received date: 2007-05-22
Revised date: 2007-06-18
Online published: 2007-07-10
A total of 614 sediment samples at an interval of about 1.5 m from all 5 sites of the Integrated Ocean Drilling Program (IODP) Expedition 311 on Cascadia Margin, northwestern Pacific were analyzed using a Beckman Coulter LS-230 Particle Analyzer. The grain-size data were then plotted against depth and compared with other potential proxies of gas hydrate-occurrence such as soupy/mousse-like fabrics in sedimentary textures, gas hydrate concentration (Sh) derived from LWD data using Archie’s relation, IR core images (infrared image) and the recovered samples of gas hydrate-bearing sediments. A good relationship was found between the distribution of coarse grains (sizes 31~63 μm and 63~125 μm) and the potential occurrence of gas hydrate across the entire gas hydrate stability zone (see the yellow zones in following 5 diagrams).
For example, the depth distribution of grain size from the Site U1326 shows clear excursions at depths of 5~8, 21~26, 50~123, 132~140, 167~180, 195~206 and 220~240 mbsf. They coincide with the potential occurrence of gas hydrate indicated by soupy/mousse-like structures, logging-derived gas hydrate concentrations (Sh) and the recovered samples of the gas hydrate bearing sand layers.
Therefore, sediment-size may have played a role in the concentration of gas hydrate. Gas hydrate occurs preferentially in relatively coarse-grained sediments (>31 μm in grain size).
Key words： Constraint; IODP 311.; Grain size of sediments; Gas hydrate
WANG Jia-sheng, GAO Yu-ya, LI Qing, YANG Cui-ping, CHEN Qi, WEI Qing, et al . Grain Size Constraint on Gas Hydrate Occurrence: Evidence from Sediment Size during IODP 311[J]. Advances in Earth Science, 2007 , 22(7) : 659 -665 . DOI: 10.11867/j.issn.1001-8166.2007.07.0659
[1]Kvenvolden K A, Lorenson T D. The global occurrence of natural gas hydrate[C]//Paull C K, Dillon W P, eds. Natural Gas Hydrate: Occurrence, Distribution and Detection. Washington DC: American Geophysical Union, 2001:3-18.
[2]Ginsburg G, Soloviev V, Matveeva T, et al. Sediment grain-size control on hydrate presence, sites 994, 995 and 997[C]//Paull C K, Matsumotor R, Wallace P J, eds. Proceeding of ODP Inital Reports 164.College Station TX: Ocean Drilling Program, 2000: 237-245.
[3]Kraemer L M, Owen R M, Dickens G R. Lithology of the upper gas hydrate zone, Blake outer ridge, a link between diatoms, porosity, and gas hydrate[C]//Paull C K, Matsumotor R, Wallace P J,eds. Proceeding of ODP Inital Reports 164. College Station TX: Ocean Drilling Program, 2000: 229-236.
[4]Su Xin, Song Chengbing, Fang Nianqiao. Vairation in grain size of sediments above BSR and correlation with the occurrence of gas hydrates on Hydrate Ridge, East Pacific[J].Earth Science Frontiers,2005,12(1):234-242.[苏新，宋成兵，方念乔. 东太平洋水合物海岭BSR以上沉积物粒度变化与气体水合物分布[J].地学前缘, 2005, 12 (1): 234-242.]
[5]Pinero E, Gracia E, Martinez-Ruiz F, et al.Gas hydrate disturbance fabrics of southern hydrate ridge sediments (ODP Leg 204): Relationship with texture and physical properties[J].Geo-Marine Letters, 2007,DOI: 10.1007/s00367-007-0077-z.
[6]Riedel M, Collett T S, Malone M J, et al.Methods[C]//Riedal M, Collett T S, Malone M J,eds. Proceedings of the Intergrated Ocean Drilling Program, 311 Expert Reports, Cacadia Margin Gas Hydrates.IODPMI/USIO, Texas A & M University, 2006:1-76.
[7]Archie G E. The electrical resistivity log as an aid in determining some reservoir characteristics[J].American Insititute of Mining, Metallurgica and Petroleum Engineers,1942,146:54-67.
[8]Collett T S. Well log evaluation of gas hydrate saturations[C]//SPWLA 39th Annual Logging Symposium. Houston (SPWLA), 1998.
[9]Collett T S, Ladd J. Detection of gas hydrate with downhole logs and assessment of gas hydrate concentrations (saturations) and gas volumes on the Blake Ridge with electrical resistivity log data[C]//Paull C K, Matsumoto R, Wallace P J, eds. Proceeding of ODP, Science Results, 164. College Station, TX (Ocean Drilling Program), 2000:179-191.
[10]Tréhu A M, Long P E, Torres M,et al.Three-dimensional distribution of gas hydrate beneath Southern Hydrate Ridge: Constraints from ODP Leg 204[J].Earth Planet Science Letters,2004,222:845-862.
/
| 〈 |
|
〉 |
