潮汕坳陷残留有巨厚的中生代沉积层, 是南海油气勘探的重要区域。已经开展了大量的多道地震反射工作, 同时也有折射地震和海底地震仪研究, 但尚未开展纵横波联合研究。纵横波联合探测, 可以获得更多的地下结构信息, 对油气勘探有重要的意义。在OBS2006-3剖面潮汕坳陷中生代沉积层纵波速度结构的基础上, 对转换横波震相进行了射线追踪和走时模拟。结果表明, 潮汕坳陷中生代沉积层厚度较大, 最大厚度达到8km, 纵波速度从顶部的4.4km·s–1增加到底部的5.3km·s–1, 相应的横波速度由2.6km·s–1增大到3.0km·s–1, 泊松比为0.24—0.26, 波速比为1.74—1.80, 其成分可能包含有砂岩、泥岩和火山岩。同时根据该区的地球物理特征, 结合前人的研究, 分析了油气勘探潜力。
As a thick residual deposition depression of the Mesozoic strata, the Chaoshan Depression is an important area for oil and gas exploration in the South China Sea (SCS). A lot of multiple-channel seismic (MCS) reflection studies have been conducted in this area, as well as refraction and ocean bottom seismometer (OBS) surveys, but joint P-wave and S-wave studies have not yet been done. Applying the joint exploration of P-wave and S-wave, the complex subsurface crustal structure can be obtained, which is helpful for oil and gas exploration. Based on the P-wave velocity structure of the Mesozoic sediments in the Chaoshan Depression of the profile OBS2006-3, we carried ray tracing and travel-time simulation of converted S-wave. The results reveal that the Mesozoic sediment in the Chaoshan Depression is remarkably thick with the maximum of 8 km, and the P-wave velocity increases downward from 4.4 km·s–1 at the top to 5.3 km·s–1 at the bottom. Accordingly, the S-wave velocity and Poisson’s ratio are 2.6?3.0km·s–1 and 0.24?0.26, respectively, which may imply the composition of Mesozoic strata are sandstone, mudstone and volcanic rocks. According to the geophysical characteristics and previous research in the Chaoshan Depression, this paper analyzes the exploration potential in the Chaoshan Depression.
[1] 刘光鼎, 陈洁. 中国前新生代残留盆地油气勘探难点分析及对策[J]. 地球物理学进展, 2005, 20(2): 273-275.
[2] 夏戡原, 黄慈流. 南海中生代特提斯期沉积盆地的发现与找寻中生代含油气盆地的前景[J]. 地学前缘, 2000, 7(3): 227-238.
[3] 王平, 夏戡原, 黄慈流. 南海东北部中生代海相地层的分布及其地质地球物理特征[J]. 热带海洋, 2000, 19(4): 28-35.
[4] 郝沪军, 张向涛. 重磁资料在潮汕坳陷中生界油气勘探中的应用[J]. 中国海上油气: 地质, 2003, 17(2): 128-132.
[5] 陈洁. 潮汕坳陷地球物理特征及油气勘探潜力[J]. 地球物理学进展, 2007, 22(1): 147-155.
[6] 邵磊, 尤洪庆, 郝沪军, 等. 南海东北部中生界岩石学特征及沉积环境[J]. 地质论评, 2007, 53(2): 164-169.
[7] 钟广见, 吴世敏, 冯常茂. 南海北部中生代沉积模式[J]. 热带海洋学报, 2011, 30(1): 43-48.
[8] 陈冰, 王家林, 钟慧智, 等. 南海潮汕坳陷前第三纪盆地结构地球物理研究[J]. 同济大学学报: 自然科学版, 2005, 33(9): 1275-1280.
[9] 郝沪军, 林鹤鸣, 杨梦雄, 等. 潮汕坳陷中生界油气勘探的新领域[J]. 中国海上油气: 地质, 2001, 15(3): 157-163.
[10] 郝沪军, 施和生, 张向涛, 等. 潮汕坳陷中生界及其石油地质条件——基于LF35-1-1探索井钻探结果的讨论[J]. 中国海上油气, 2009, 21(3): 151-156.
[11] 吴国瑄, 王汝建, 郝沪军, 等. 南海北部海相中生界发育的微体化石证据[J]. 海洋地质与第四纪地质, 2007, 27(1): 79-85.
[12] 郝沪军, 汪瑞良, 张向涛, 等. 珠江口盆地东部海相中生界识别及分布[J]. 中国海上油气: 地质, 2004, 16(2): 84-88.
[13] 吕修亚, 阎贫, 陈洁, 等. 折射方法在南海北部潮汕坳陷中生界地层研究中的应用[J]. 热带海洋学报, 2009, 28(1): 43-47.
[14] 阮爱国, 牛雄伟, 吴振利, 等. 潮汕坳陷中生代沉积的折射波2D速度结构和密度[J]. 高校地质学报, 2009, 25(4): 417-423.
[15] 罗文造, 阎贫, 温宁, 等. 南海北部潮汕坳陷海区海底地震仪调查实验[J]. 热带海洋学报, 2009, 28(4): 59-65.
[16] 卫小冬, 阮爱国, 赵明辉, 等. 穿越东沙隆起和潮汕坳陷的OBS广角地震剖面[J]. 地球物理学报, 2011, 54(12): 3325-3335.
[17] 李湘云, 吴振利, 薛彬, 等. SEDIS Ⅳ型短周期自浮式海底地震仪及应用体会[J]. 热带海洋学报, 2007, 26(5): 735-39.
[18] 吴振利, 阮爱国, 李家彪, 等. 南海中北部地壳深部结构探测新进展[J]. 华南地震, 2008, 28(1): 21-28.
[19] 卫小冬, 赵明辉, 阮爱国, 等. 南海中北部OBS2006-3地震剖面中横波的识别与应用[J]. 热带海洋学报, 2010, 29(5): 72-80.
[20] 卫小冬, 赵明辉, 阮爱国, 等. 南海中北部陆缘横波速度结构及其构造意义[J]. 地球物理学报, 2011, 54(12): 3150-3160.
[21] ZELT C, SMITH R. Seismic travel time inversion for 2-D crustal velocity structure[J]. Geophys J Int, 1992, 108: 16-34.
[22] KODAIRA S, BELLENBERG M, IWASAKI T. Vp/Vs ratio structure of the Lofoten continental margin, northern Norway, and its geological implications[J]. Geophys J Int, 1996, 124: 724-740.
[23] 赵明辉, 丘学林, 夏少红, 等. 南海东北部三分量海底地震仪记录中横波的识别与分析[J].自然科学展, 2007, 17(11): 1516-1523.
[24] ZHAO MINGHUI, QIU XUELIN, XIA SHAOHONG, et al. Seismic structure in the northeastern South China Sea: S-wave velocity and Vp/Vs ratios derived from three- component OBS data[J]. Tectonophysics, 2010, 480: 183-197.
[25] 阎贫. 海底地震仪记录中的横波[J]. 海洋地质与第四纪地质, 1998, 18(1): 115-118.
[26] TINIVELLA U, ACCAINO F. Compressional velocity structure and Poisson’s ratio in marine sediments with gas hydrate and free gas by inversion of reflected and refracted seismic data (South Shetland Islands, Antarctica)[J]. Marine Geology, 2000, 164:13-27.
[27] 黄绪德. 地震勘探直接找油气在国外的最新发展[J]. 勘探地球物理学进展, 2004, 27(3): 218-227.