Combining 2D-basin and structural modelling to constrain heat transport along the Muroto Transect,Nankai Trough,Japan

The Nankai Trough located southeast of Shikoku Island, Japan, exhibits a zone of exceptionally high heat flow. In the central part of the Nankai Trough the fossil spreading centre of the Shikoku Basin is subducted beneath the southwest Japan arc. We have modelled the temperature and maturation history along the Muroto Transect reaching from the tip of the thrust zone out into nearly undeformed Quaternary and Tertiary sediments seawards of Nankai Trough. We used two balanced cross-sections defining the sections before and after overthrusting as input for 2D-basin modelling. We can show that rapid burial and overthrusting during the Quaternary in combination with a heat flow history following the cooling curve of a 15 Ma old oceanic plate is not sufficient to explain the measured maturity of organic material in the sediments. Several heat flow scenarios derived from theoretical concepts [Yamano, M., Kinoshita, M., Goto, S., Matsubayashi, O., 2003. Extremely high heat flow anomaly in the middle part of the Nankai Trough. Physics and Chemistry of the Earth, Parts A/B/C 28, 487–497.] and previous modelling approaches [e.g. Brown, K.M., Saffer, D.M., Bekins, B.A., 2001. Smectite diagenesis, pore water freshening, and fluid flow at the toe of the Nankai wedge. Earth and Planetary Science Letters 194, 97–109; Spinelli, G.A., Underwood, M.B., 2005. Modeling thermal history of subducting crust in Nankai Trough: constraints from in situ sediment temperature and diagenetic reaction progress. Geophysical Research Letters 32(L09301): doi:10.1029/2005GL022793; Steurer, J., Underwood, M.B., 2003. Clay mineralogy of mudstones from the Nankai Trough reference sites 1173 and 1177 and frontal accretionary prism site 1174. In: H. Mikada et al. (Eds.), pp. 1–37. Available from: <http://www-odp.tamu.edu/publications/190196SR/VOLUME/CHAPTERS/211.PDF>] were tested. The best match between observed maturity levels, temperature and heat flow measurements is reached for a heat flow history which initially assumes the cooling of a 15 Ma old oceanic lithosphere but is reheated to 170–180 mW/m² during the phase of rapid burial in the Quaternary. This can be achieved either by assuming the onset of hydrothermal circulation in the cooling crust or by reheating caused by off-axis volcanism at about 6 Ma [Yamano, M., Kinoshita, M., Goto, S., Matsubayashi, O., 2003. Extremely high heat flow anomaly in the middle part of the Nankai Trough. Physics and Chemistry of the Earth, Parts A/B/C 28, 487–497.].     

Marine genetic resources: A review of scientific and commercial interest

Marine genetic resources both within and beyond national jurisdiction have been the focus of international negotiations in a range of forums in recent years. One recurrent theme throughout these discussions has been the absence of detailed information upon which policy responses to the emerging issue of the conservation and sustainable use of marine genetic resources (especially in areas beyond national jurisdiction) could be based. In an effort to address some of these knowledge gaps, this article examines the level and nature of scientific and commercial interest in marine genetic resources, including in areas beyond national jurisdiction. It also examines the changing perspectives of the scientific community in relation to the potential of marine genetic resources.     

高平4水平井组双保钻井液技术

高平4井组水平井主要用于开发安塞长10组油藏。针对该井组上部直罗组和富县组易坍塌、下部地层钻速相对较慢、地层易造浆的特点,研究应用了环保型聚硅酸盐-黄胞胶钻井液体系。该体系具有抑制性强、润滑和剪切稀释性好的特点,有利于安全快速钻井,对环境污染极小。通过小型配浆实验确定钻井液施工方案,中测后稀释钻井液,降低钻井液滤失量和密度,加强固相控制,使用保护油层的酸溶性暂堵剂和降滤失剂,可最大限度地保护油层。     

南堡1—5海上导管架批量优快钻井技术

为加快南堡1号构造的开发速度,冀东油田在南堡1—5海上导管架尝试实施了批量钻井技术。针对南堡1—5海上导管架井口间距小的特点,对井口布置、优选及轨迹设计进行了深入研究和论证,并对施工顺序、工艺作了精细安排,保证了钻井施工的顺利,提高了钻井速度。南堡1～5井组5口井平均钻井周期为16．72d,较未实施批量钻井单井钻井周期缩短30％以上。该项技术为缓解海上钻井平台紧张被动局面提供了一个行之有效的解决方案,同时为人工岛模块钻机高效利用提供了新思路。     

我国海岸工程技术展望

从海岸动力监测体系、河口海岸侵蚀及防护、海岸工程深水和离岸趋势、极端条件下海岸工程结构安全、岛礁工程开发技术、海岸管理与数字海岸、亲水工程、海洋能技术利用开发和海岸工程研究等九个方面对我国海岸工程中面临的问题,以及国外相关工程技术进展情况进行了分析,并指出我国未来海岸工程领域需要加以关注的重点问题和发展趋势。     

深部地质钻探孔内钻杆动力响应特性研究

深部地质钻探时,钻杆受力条件复杂,振动形式多变且剧烈.为认识钻杆的动力学特征,减少钻杆失效风险,提高钻进效率,建立了仅考虑纵向振动和扭转振动耦合作用下的深部地质钻杆动力学分析模型,并推导了钻杆固有振动频率公式,在此基础上,借助ANSYS软件进行仿真分析.研究成果表明:在纵向(扭转)振动下,随着模态阶数的增加,钻杆的轴向...     

综合物探方法在广西罗城县活动断裂鉴定中的应用

城市活动断层探测在城市发展建设过程中和保障人民生命财产安全方面起到重要作用.本文以鉴定罗城断裂和上天桥—寺门断裂活动性为目的,在地震地质调查确定其断裂的几何学、运动学和年代学的基础上,选择第四系覆盖断裂最有可能活动的地段,重点采用高密度电法和地震映像方法来探测断裂在隐伏地段的具体位置,通过排钻验证,以及揭露其断裂与第四...     

平台运动下深水钻井隔水管非线性动力响应研究

建立深水钻井隔水管在波、流和平台运动的联合作用下的运动方程,模拟1 000 m深水钻井隔水管的非线性动力响应.分析在波、流作用下钻井液密度和顶部张力比等因素对隔水管振动频率的影响,研究平台的静偏移和动态运动对隔水管最大弯矩分布的影响.结果表明,平台运动对深水钻井隔水管的动力响应有较大影响,使隔水管上部最大弯矩峰值增加了1倍多.     

Research on Horizontal Vibration of Heavy-Weight Drill Pipes in Directional Drilling

The mode of load and deformation of directional drilling string and the expression of trigonometric series of deflection equation are established by means of elastic deformation energy and of the vertical and horizontal bending. A calculation formula for natural frequency of horizontal resonance and rotational speed is derived based on the calculation method by Ritz, with which analysis is made for the cause and affecting factors of the excessive abrasion of heavy-weight drill pipe in high-angle holes so as to provide reference and basis for rational selection of drilling parameters and drilling tools in the future high-angle directional drilling.     

第八次南极考察随船海洋气象考察报告

本文介绍了第八次随船海洋气象考察工作情况,用天气学的方法分析了夏季影响考察航线及大洋调查海区的主要天气系统及其特点,通过实例总结了随船天气预报工作的体会和经验。