Journal of Tropical Oceanography >
Velocity features of gas-hydrate stratigraphy based on OBS and MCS data
Received date: 2019-04-21
Request revised date: 2019-09-24
Online published: 2020-03-10
Supported by
National Key Research and Development Program of China(2018YFC0309801、2017YFC0307401)
National Natural Science Foundation of China(41674092、41730532)
Copyright
Natural gas-hydrate is a new clean energy resource. The geological conditions in Shenhu area in the northern South China Sea (SCS) are conducive to the formation and storage of gas-hydrate. It is difficult to obtain accurate velocity information from traditional multi-channel seismic (MCS) data, and we can only judge the vertical distribution of geological bodies from the time domain. Ocean bottom seismometer (OBS) is a widely used active-source seismic instrument, which can receive clearer air gun signals. Compared with MCS data, refraction seismic data of OBS profiles can reveal velocity information from deeper layers. In this paper, combining the advantages of MCS and OBS, we determine the reflection interfaces on MCS profile, and then obtain the initial model. The OBS and MCS stacking profiles are merged to determine the reflection interface in the OBS profile. The reflection and refraction phases of OBS stations were picked up, and the two-dimensional velocity model of hydrate region was obtained by forward modeling using RayInvr, which solved the difficult time-depth conversion problem in MCS. The final model shows the depth, thickness and velocity of hydrate and free gas regions; it also shows the depth and velocity characteristics of the deeper interface below BSR.
LI Zizheng , QIU Xuelin , XING Lei . Velocity features of gas-hydrate stratigraphy based on OBS and MCS data[J]. Journal of Tropical Oceanography, 2020 , 39(2) : 25 -34 . DOI: 10.11978/2019040
图1 南海北部水合物勘探和研究区位置[据Xing等(2018)修改]本文选取的SH000测线位于橙色方框内 Fig. 1 Location map of exploration and study area in the northern South China Sea. Modified from Xing et al (2018) |
图6 OBS05台站的射线追踪(a)和走时拟合(b)红: 直达水波路径及震相; 绿: 来自BSR的反射波路径及震相; 黄: 游离气底界的反射波路径及震相; 蓝、青: 深部地层的折射波路径及震相 Fig. 6 Ray tracing (a) and travel time fits (b) of OBS05. Red: direct water wave, Green: Reflection from BSR, Yellow: Reflection from bottom of the free gas layer, Blue and Cyan: Refraction waves from deeper layers |
图7 全部OBS台站的射线追踪(a)和走时拟合(b)图b中黑线为理论到时, 彩线为拾取的实际震相(4906个); 红: 直达水波震相; 橙: 浅部沉积层的反射波; 绿: 来自BSR的反射波; 黄: 游离气底界的反射波; 蓝、青: 深部地层的折射波震相; χ2值为1.079; RMS值为0.024s Fig. 7 Ray tracing (a) and travel time fits (b) of all OBS stations. The black line in (b) represents calculated arrival times, and the colored line indicates observed arrival times (4096). Red: direct water wave; Orange: Reflection from shallow sediment layers; Green: Reflection from BSR; Yellow: Reflection from bottom of the free gas layer; Blue and Cyan: Refraction waves from deeper layers; χ2 =1.079; RMS=0.024s |
图8 最终模型射线覆盖次数黑色实线代表模型界面(有震相约束), 黑色虚线代表水合物顶界(无震相约束); 黑色箭头表示游离气运移方向; 红色虚线表示折射波在地层顶部传播路径; 6个OBS台站用黄色圆圈表示 Fig. 8 Ray coverage of the final model. Black solid line indicates the interface of the model (constrained by seismic waves); Black dashed line indicates the top of gas-hydrate (without seismic waves); Black arrow indicates the migration of free gas; Red dashed line indicates the ray-path of refraction waves on the top of layer; Positions of 6 OBS stations are indicated by yellow circles |
图9 最终速度模型(a)和SH3测井曲线(黑线)和模型曲线(红线) (b)黑色实线代表模型界面(有震相约束), 黑色虚线代表水合物定界(无震相约束); 黑色箭头表示游离气运移方向; 蓝色虚线表示折射波约束的顶层速度; 6个OBS台站用黄色圆圈表示 Fig. 9 Final velocity model (a), well logging (black) and 1-D velocity values (red) beneath SH3 (b).Black solid line indicates the interface of the model (constrained by seismic waves); Black dashed line indicates the top of gas-hydrate (without seismic waves); Black arrow indicates the migration of free gas; Blue dashed line indicates the velocity constrained by the refraction waves on the top of layer; Positions of 6 OBS stations are indicated by yellow circles |
1 |
敖威, 赵明辉, 丘学林 , 等, 2010. 西南印度洋中脊三维地震探测中炮点与海底地震仪的位置校正[J]. 地球物理学报, 53(12):2982-2991.
AO WEI, ZHAO MINGHUI, QIU XUELIN, et al, 2010. The correction of shot and OBS position in the 3D seismic experiment of the SW Indian Ocean Ridge[J]. Chinese Journal of Geophysics, 53(12):2982-2991 (in Chinese with English abstract).
|
2 |
梁劲, 王明君, 陆敬安 , 等, 2013. 南海北部神狐海域含天然气水合物沉积层的速度特征[J]. 天然气工业, 33(7):29-35.
LIANG JIN, WANG MINGJUN, LU JING’AN, et al, 2013. Characteristics of sonic and seismic velocities of gas hydrate bearing sediments in the Shenhu area, northern South China Sea[J]. Natural Gas Industry, 33(7):29-35 (in Chinese with English abstract).
|
3 |
马在田, 宋海斌, 孙建国 , 2000. 海洋天然气水合物的地球物理探测高新技术[J]. 地球物理学进展, 15(3):1-6 .
MA ZAITIAN, SONG HAIBIN, SUN JIANGUO, 2000. Geophysical prospecting high technologies of marine gas hydrates[J]. Progress in Geophysics, 15(3):1-6 (in Chinese with English abstract).
|
4 |
丘学林, 赵明辉, 敖威 , 等, 2011. 南海西南次海盆与南沙地块的OBS探测和地壳结构[J]. 地球物理学报, 54(12):3117-3128.
QIU XUELIN, ZHAO MINGHUI, AO WEI, et al, 2011. OBS survey and crustal structure of the Southwest Sub-basin and Nansha Block, South China Sea[J]. Chinese Journal of Geophysics, 54(12):3117-3128 (in Chinese with English abstract).
|
5 |
宋海斌, 耿建华 ,
SONG HAIBIN, GENG JIANHUA, WANG H-K, et al, 2001a. A preliminary study of gas hydrates in Dongsha region north of South China Sea[J]. Chinese Journal of Geophysics, 44(5):687-695 (in Chinese with English abstract).
|
6 |
宋海斌, 松林修, 杨胜雄 , 等, 2001 b. 海洋天然气水合物的地球物理研究(Ⅱ): 地震方法[J]. 地球物理学进展, 16(3):110-118.
SONG HAIBIN, OSAMU M, YANG SHENGXIONG, et al, 2001b. Geophysical researches on marine gashydrates(Ⅱ): seismic methods[J]. Progress in Geophysics, 16(3):110-118 (in Chinese with English abstract).
|
7 |
苏正, 曹运诚, 杨睿 , 等, 2014. 南海北部神狐海域天然气水合物成藏模式研究[J]. 地球物理学报, 57(5):1664-1674.
SU ZHENG, CAO YUNCHENG, YANG RUI, et al, 2014. Research on the formation model of gas hydrate deposits in the Shenhu Area, Northern South China Sea[J]. Chinese Journal of Geophysics, 57(5):1664-1674 (in Chinese with English abstract).
|
8 |
王祥春, 王延峰, 夏常亮 , 等, 2012. Kirchhoff积分法OBS数据地震波场延拓[J]. 现代地质, 26(6):1231-1236.
WANG XIANGCHUN, WANG YANFENG, XIA CHANGLIANG, et al, 2012. Extrapolating the OBS data using the Kirchhoff integral method[J]. Geoscience, 26(6):1231-1236 (in Chinese with English abstract).
|
9 |
魏伟, 张金华, 孙爱 , 等, 2009. 天然气水合物勘查识别与实验技术[J]. 天然气工业, 29(9):123-125.
WEI WEI, ZHANG JINHUA, SUN AI, et al, 2009. Exploratory identification of and modeling experiments on natural gas hydrate[J]. Natural Gas Industry, 29(9):123-125 (in Chinese with English abstract).
|
10 |
吴时国, 姚根顺, 董冬冬 , 等, 2008. 南海北部陆坡大型气田区天然气水合物的成藏地质构造特征[J]. 石油学报, 29(3):324-328.
WU SHIGUO, YAO GENSHUN, DONG DONGDONG, et al, 2008. Geological structures for forming gas hydrate reservoir in the huge deepwater gas field of the northern South China Sea[J]. Acta Petrolei Sinica, 29(3):324-328 (in Chinese with English abstract).
|
11 |
徐云霞, 文鹏飞, 张宝金 , 等, 2018. 琼东南海域OBS纵波资料成像处理关键技术[J]. 海洋地质与第四纪地质, 38(5):185-192.
XU YUNXIA, WEN PENGFEI, ZHANG BAOJIN, et al, 2018. The key technique of OBS p-wave imaging processing in Qiongdongnan area[J]. Marine Geology & Quaternary Geology, 38(5):185-192 (in Chinese with English abstract).
|
12 |
于德福, 陈惠玲, 朱夏 , 2017. 我国海域天然气水合物试采成功[J]. 国土资源通讯, ( 10):4 (in Chinese).
|
13 |
于兴河, 王建忠, 梁金强 , 等, 2014. 南海北部陆坡天然气水合物沉积成藏特征[J]. 石油学报, 35(2):253-264.
YU XINGHE, WANG JIANZHONG, LIANG JINQIANG, et al, 2014. Depositional accumulation characteristics of gas hydrate in the northern continental slope of South China Sea[J]. Acta Petrolei Sinica, 35(2):253-264 (in Chinese with English abstract).
|
14 |
张光学, 徐华宁, 刘学伟 , 等, 2014 a. 三维地震与OBS联合勘探揭示的神狐海域含水合物地层声波速度特征[J]. 地球物理学报, 57(4):1169-1176.
ZHANG GUANGXUE, XU HUANING, LIU XUEWEI, et al, 2014a. The acoustic velocity characteristics of sediment with gas hydrate revealed by integrated exploration of 3D seismic and OBS data in Shenhu area[J]. Chinese Journal of Geophysics, 57(4):1169-1176 (in Chinese with English abstract).
|
15 |
张光学, 梁金强, 陆敬安 , 等, 2014 b. 南海东北部陆坡天然气水合物藏特征[J]. 天然气工业, 34(11):1-10 .
ZHANG GUANGXUE, LIANG JINQIANG, LU JING’AN, et al, 2014b. Characteristics of natural gas hydrate reservoirs on the northeastern slope of the South China Sea[J]. Natural Gas Industry, 34(11):1-10 (in Chinese with English abstract).
|
16 |
张光学, 梁金强, 张明 , 等, 2014c. 海洋天然气水合物地震联合探测[M]. 北京: 地质出版社(in Chinese).
|
17 |
张莉, 赵明辉, 王建 , 等, 2013. 南海中央次海盆OBS位置校正及三维地震探测新进展[J]. 地球科学——中国地质大学学报, 38(1):33-42.
ZHANG LI, ZHAO MINGHUI, WANG JIAN, et al, 2013. Correction of OBS position and recent advances of 3D seismic exploration in the central sub-basin of South China Sea[J]. Earth Science—Journal of China University of Geosciences, 38(1):33-42 (in Chinese with English abstract).
|
18 |
|
19 |
|
20 |
|
21 |
|
22 |
|
23 |
|
24 |
|
25 |
|
26 |
|
27 |
|
28 |
|
/
〈 |
|
〉 |