Velocity-Interface Structure of the Southwestern Ryukyu Subduction Zone from EW9509-1 OBS/MCS Data

A wide-angle seismic survey, combining ocean-bottom seismometers (OBS) and multi-channel seismic (MCS) profiling, was implemented in the southwestern Ryukyu subduction zone during August and September 1995. In this paper, we present the data analysis of eight OBSs and the corresponding MCS line along profile EW9509-1 from this experiment. Seismic data modeling includes identification of refracted and reflected arrivals, initial model building from velocity analysis of the MCS data, and simultaneous and layer-stripping inversions of the OBS and MCS arrivals. The velocity-interface structure constructed along profile EW9509-1 shows that the northward subduction of the Philippine Sea Plate has resulted in a northward thickening of the sediments of the Ryukyu Trench and the Yaeyama accretionary wedge north of the trench. The boundary between the subducting oceanic crust and the overriding continental crust (represented by a velocity contour of 6.75 km/s) and a sudden increase of the subducting angle (from 5 degrees to 25 degrees) are well imaged below the Nanao Basin. Furthermore, velocity undulation and interface variation are found within the upper crust of the Ryukyu Arc. Therefore, the strongest compression due to subduction and a break-off of the slab may have occurred and induced the high seismicity in the forearc region. This revised version was published online in November 2006 with corrections to the Cover Date.     

声波对海洋生物的影响与作用的研究

本文研究了声波对某些海洋生物的影响与作用。实验表明，适当的声波剂量对海洋生物的作用所产生的声学生物效应是积极的，可促使生物体向有利的方向产生变异，而强度过大的声波对海洋生物有效伤甚至致死的效应。     

井中激电地-井方式井旁球体正反演

以激发极化法中的地-井方式中的体极化球形体作为研究对象,采用解析法对地下半空间的电位场进行求解,利用提取出的井中二次场异常电位差进行反演,得出极化球体的球心离井的距离和球心的埋深。通过计算机进行正反演模拟,验证了进行正反演计算的解析式的正确性,并从物理意义上对正反演过程中出现的现象进行分析。最后给出该方法的适用条件以及注意事项。研究对激发极化法地下勘探目标的定量分析具有明确意义。     

地面核磁共振模型约束反演含水层参数

导电模型的地面核磁共振感应电动势是含水量的非线性函数.引入模型约束的迭代反演方法求解该非线性问题的反演.在反演过程中,根据理论公式计算迭代过程中灵敏度矩阵,并采用平坦模型和光滑模型两种约束.对均匀半空间、层状导电模型和实际数据进行了反演模拟,结果表明,模型约束迭代反演方法能从地面核磁共振感应电动势获得含水层较为合理的含水量及分布,且该结果可以从作为初始模型的均匀含水量分布反演得到.对无噪音数据,平坦模型和光滑模型约束对反演的含水量分布影响不大;但当数据存在一定的噪音时,平坦模型约束将比光滑模型约束获得更为精确的含水层参数.     

小波边缘分析建模波阻抗反演方法在煤层解释中的应用

受限于地震波主波长的1／4,常规地震处理难以分辨较薄煤层。基于模型的波阻抗反演虽然克服了厚、薄煤层计算问题．但因难以得到准确的高频部分,很多情况下反演结果的精度和分辨率往往不能满足地质预测的要求。小波边缘分析建模波阻抗反演方法是从地震数据中提取地震特征参数,用于建模并参与迭代反演。该方法即可以弥补反演过程中高频成分的误差,减少对钻井数据的依赖程度,得到较为合理的初始模型,又可提高反演的精度和分辨率．使反演结果更好的反映实际地下地质情况。利用该方法,对大井-将军庙及新疆红沙泉2个勘探区的侏罗系中统西山窑组含煤地层进行波阻抗反演,反演结果与钻井资料进行比较,其中大井一将军庙0802及0809号孔单煤层厚度误差分别为3％、8％．新疆红沙泉多煤层厚度及煤层之间的夹层厚度预测结果除B6煤层误差较大外,其它误差均小于7％．可见该反演方法的计算结果比较准确。     

煤层气固井声幅测井方法探讨

影响煤层气固井声幅测井的因素较多,如地层软硬变化大、套管内径或壁厚不均、仪器不居中、发射能量不足、接收灵敏度不够等,这些因素的存在将会导致首波丢失、时差曲线产生周波跳跃或波动现象。为提高煤层气固井声幅测井质量,要尽量保证所用仪器外径接近套管内径,以减少无效传播和能量损失,另外需提高仪器的发射能量及接收灵敏度;在自由套管和声波强吸收地层,必须保证自由套管首波不限幅、声波强吸收地层首波不丢失。在现场解释时,一般以＂自由套管＂处的偏转幅度值A为标准,将固井声幅曲线幅度的20%A和40%A作为分界点,评价固井效果。     

努力提高三维地震勘探精度，为西部煤炭工业做出新贡献

以国家重大产业技术开发专项“西部煤炭资源高精度三维地震勘探技术”项目的由来、意义和总体研究目标为引,概括的介绍了项目依托工程中各个专项技术研究完成情况,并对非均匀介质成像技术、高精度三维地震静校正技术、高密度采集技术、特观技术、岩性反演技术、属性体解释技术等六项重大关键技术取得的突破性进展进行了重点说明。指出随着我国煤炭生产重点的逐步西移,应加强诸如叠前、叠后深度偏移技术的研究,以解决复杂山区三维地震面元内地震反射波散射问题,提高其三维地震勘探精度,为西部煤炭工业做出新贡献!     

三维地震技术在煤层顶板稳定性研究中的应用

龙固井田为全隐蔽的华北型煤田,位于巨野煤田中部,其首采扩大区主采煤层为3号煤层。考虑3煤层顶板稳定性主要受其顶板的构造信息和岩性信息影响,因此首先依据三维地震勘探综合解释成果及波阻抗反演解释成果对二者进行定量化,然后对波阻抗数据进行归一化处理,使得波阻抗数据和量化后的构造数据具有相同的变化范围及等量贡献。在此距离范围内构造和岩性的权值各为0．5,依此生成综合因素煤层顶板稳定性隶属度。分析3煤层顶板以上10m、20m处的综合因素煤层顶板稳定性隶属度图可以发现,该区3煤层顶板稳定性比较好。且其稳定性主要是受构造因素控制,岩性因素相对影响较小。     

SOME NEW UNDERSTANDINGS OF LAND-SURFACE PROCESSES IN ARID AREA FROM THE HEIFE*

The survey for the HEIFE(Atmosphere-Land Surface Processes Experiment at Heihe River Basin,Western China) is given in the paper.The following basic subjects for land-surface processes in arid areas are studied:(1) the general characteristics of the energy budget on ground surface in arid areas;(2) the parameterization of the land surface processes;(3) the interaction between oasis and its desert circumstances,a special phenomenon in arid areas.The analysis shows that the sensible heat flux in the surface energy budget is in the majority,and the latent heat flux may be neglected.The influence of atmospheric stratification stability on the turbulent transfer of energy and substance must be considered in parameterization of land surface processes in arid areas.The "cold island effect" phenomenon in oasis and the "humidity inversion" phenomenon in desert near oasis are the result of the interaction between them.The results would improve the understanding of land surface processes in arid areas.