The Seismic Detecting Technique on Gas Hydrates Based on Wave Impedance Inversion

Abstract

Abstract:

As specific geologic body, gas hydrate can cement effectively clastic particles and reduce porosity of deposition, so its presence changes physical property of the sedimentary strata and results in the difference of seismicwave velocity between gas hydrate and the surrounding rock, and there exists obviously wave impedance difference. In order to detect the presence of sediments with gas hydrate, seismic data of gas hydrate zone in the Shenhu area of the northern South China Sea were used in the wave impedance inversion through practice, testing and summary. Wave impedance inversion method is considered as a kind of good seismic detection technique for identification of gas hydrates, meanwhile, the wave impedance of gas hydrate zone shows high value in the study area, and the wave impedance value is about 3,850-3,960 g/cm3•m/s. All the results suggested that wave impedance inversion can be used for detection，reservoir analysis and comprehensive research of gas hydrates. The wave impedance inversion results can provide comparatively accurate area and thickness parameters of gas hydrate zone for reserves calculation.

Key words: wave impedance inversion, seismic detecting technique

CLC Number:

P631.4

SHA Zhi-Bin,ZHENG Tao, YANG Mu-Zhuang,WANG Ming-Jun,LIANG Jin-qiang. The Seismic Detecting Technique on Gas Hydrates Based on Wave Impedance Inversion[J]. Geoscience, 2010, 24(3): 481-488.

References

[1]金庆焕.天然气水合物——未来的新能源［J］.中国工程科学,2000(2):29-34.

[2]李正文,赵志超.地震勘探资料解释［M］.北京:地质出版社,1988: 1-100.

[3]张光学,黄永样,陈邦彦,等.海域天然气水合物地震学［M］.北京:海洋出版社,2003:1-254.

[4]宋海斌,张岭,江为为,等.海洋天然气水合物的地球物理研究(Ⅲ):似海底反射［J］.地球物理学进展,2003,18(2):182-187.

[5]Miller J J, Myung W L,Von Huene R.An analysis of a reflection from the base of a gas hydrate zone of Peru［J］. American Association of Petroleum Geologists Bulletin,1991,75:910-924.

[6]刘学伟，李敏锋，张聿文，等.天然气水合物地震响应研究——中国南海HD152测线应用实例［J］.现代地质,2005,19(1):33-38.

[7]Hyndman R D, Spence G D.A seismic study of methane hydrate marine bottom simulating reflectors［J］. Journal of Geophysical Research, 1992,97:6683-6698.

[8]Ecker C, Dvorkin J, Nur A M. Estimating the amount of gas hydrate and free gas from marine seismic data［J］.Geophysics，2000，65:565-573.

[9]Lee M W. Seismic character of gas hydrates on the southeastern U.S. continental margin［J］. Marine Geophysical Researches, 1993, 16:163-184.

[10]马在田,耿建华,董良国,等.海洋天然气水合物的地震识别方法研究［J］.海洋地质与第四纪地质,2002，22(1):1-8.

[11]Shiply T H. Seismic evidence for widespread possible gas hydrate horizons on continental slopes and rises［J］. AAPG Bulletin, 1979, 63:2204-2213.

[12]孙春岩,章明昱,牛滨华,等.天然气水合物地震空白带现象正演模型研究［J］.地学前缘,2003,9(1):199-204.

[13]Singh Satish C, Minshull Timothy A. Velocity structure of a gas hydrate reflector at Ocean Drilling Program Site 889 from a global seismic waveform inversion［J］. Journal of Geophysical Research: Solid Earth and Planets, 1994,99:221-233.

[14]Ewing J I, Hollister C H. Regional aspects of deep sea drilling in the western North Atlantic: Initial Reports of Deep Sea Drilling Project［M］. Washington: Government Printing Office, 1972: 951-971.

[15]Tucholke B E, Bryan G M, Ewing J I. Gashydrate horizons detected in seismicprofile data from the western North Atlantic［J］. American Association of Petroleum Geologists Bulletin, 1977, 61: 698-707.

[16]张光学.海底气体水合物BSR的AVO模拟［J］.海洋地质,2001，42(2):54-60.

[17]王淑红,宋海滨,颜文,等.天然气水合物稳定带的计算方法与参数选择探讨［J］.现代地质,2005,19(1):101-107.

[18]Andreassen K, Hart P E, Grantz A. Seismic studies of a bottom simulating reflection related to gas hydrate beneath the continental margin of the Beaufort Sea［J］. Journal of Geophysical Research: Solid Earth and Planets, 1995,100:659-673.

[19]Katzman R, Holbrook W S, Paull C K. Combined verticalincidence and wideangle seismic study of a gas hydrate zone, Blake Ridge［J］. Journal of Geophysical Research：Solid Earth and Planets, 1994,99:975-995.

[20]Schnurle K P, Liu C S, Hsiuan T H,et al. Characteristics of gas hydrate and free gas offshore southwestern Taiwan from a combined MCS/OBS data analysis［J］. Marine Geophysical Research，2004，25:157-180.

[21]Tinivella U，Accaino F，Della Vedova B. Gas hydrates and active mud volcanism on the South Shetland continental margin, Antarctic Peninsula［J］. GeoMarine Letters，2008，28:97-106.

[22]Zelt C A, Smith R B. Seismic travel time inversion for 2D crustal velocity structure［J］.Geophysical Journal International, 1992, 108:16-34.