地震速度资料在北黄海盆地中的应用

概述了北黄海盆地的区域地质背景和速度分析的原理,通过对北黄海盆地速度谱的解释和计算,得到了层速度、平均速度、砂岩百分含量等信息,利用这些速度资料识别多次波、辨别坳陷区和隆起区,进行时深转换、构造分析以及岩性分析,为北黄海盆地地震资料解释、沉积相分析以及资源量计算提供可靠的依据。     

Late pleistocene (Devensian) glaciofluvial outwash at Banc-y-Warren,near Cardigan (west Wales)

On the southwest-facing slopes of a bedrock ridge lying between Cardigan Bay to the north and the Afon Teifi to the south stands a group of hills in which 30-35 m of cross-laminated and parallel-laminated sands with lenticular upward-fining gravel sequences are overlain by 10-12 m of gravel in a single foreset bed. The sediments mantle a surface of till sloping gently toward the southwest, were transported toward the southwest (across one margin of the Afon Teifi valley), and were cut by a system of densely arranged conjugate normal faults striking northwest-southeast. The lenticular gravels and fault system suggest that the deposits accumulated as a glaciofluvial outwash spread, and on top of an ice-lobe that became isolated in the Teifi valley during the downwasting of a glacier which had occupied Cardigan Bay and much of the country to the south. The large gravel foresets capping the succession are the only indication at Banc-y-Warren of the former existence of a lake, but neither a large nor deep body of water need be envisaged.     

南麂列岛大沙岙沙滩贝类的时空分布

南麂列岛作为观光旅游的休闲去处正在日益升温,其中沙滩游玩是最大的活动亮点,大沙岙是南麂列岛最具代表性的沙滩,沙滩内生活着较多贝类,随大量人员的涌入和沿岸环境污染的日趋加重,大沙岙沙滩贝类的栖息地环境受到了较大程度的危害、人为活动正影响着贝类的生长发育。为探明近年来大沙岙贝类种类、数量及群落结构的变化,在南麂列岛国家海洋自然保护区建立初期(1992年)生态调查的基础上,于2003年再次对大沙岙贝类进行了采样分析,结果表明:大沙岙沙滩12种贝类的平均生物量和栖息密度分别为30.16g/m2和20个/m2,北断面开放区贝类的平均生物量和栖息密度(13.98g/m2和11个/m2)明显少于受监控的南断面核心区(46.33g/m2和30个/m2),贝类的平均生物量和栖息密度的垂直分布低潮区(48.43g/m2和31个/m2)高于中潮区(28.03g/m2和20个/m2),贝类的平均栖息密度7月高于3月,北断面贝类的季节变化、多样性和均匀度指数大于南断面。与建区初期同季调查资料比对发现,2003年北断面贝类数量下降幅度(14倍)显著大于南断面贝类下降幅度(1倍)。分析认为,自然环境变化和人为采捕是影响沙滩贝类数量下降的主要外部因子。     

高压气藏不动管柱分层压裂工艺研究与应用

川西低渗高压气藏具有多层系的特点,层间距离一般在十至百米左右。为了提高气井产量与开采经济效益,鉴于气井加砂压裂后压井会严重伤害储层,影响压裂效果,采用压裂管柱直接作为生产管柱,研究形成了以FCY211及Y241封隔器不同组合的两层不动管柱分层压裂工艺。同时,在成熟的两层分压工艺基础上,结合投球选压工艺,研究形成了以“工具分层＋投球选压”不动管柱三层分层的压裂工艺。现场应用实践表明,分层压裂极大地增加了单井的产能,取得了明显经济效益,对类似气藏的多层压裂与开采提供了有益参考。     

加蓬G4-188区块钻井技术实践认识

加蓬G4-188区块是一个新的海外勘探区块,在钻井过程中遇到了井壁垮塌、气侵、井斜控制困难等诸多难题,影响了钻井施工的速度。针对这些难题,实施了解决G4-188区块钻井施工难点的各项技术措施,为G4-188区块后续钻井施工提供了有益的技术支持。     

Effects of long-term cyclic horizontal loading on bucket foundations in saturated loose sand

A 1-g model experimental study was conducted to investigate the accumulated rotations and unloading stiffness of bucket foundations in saturated loose sand. One-way horizontal cyclic loading was applied to model bucket foundations with embedment ratios 0.5 and 1.0. Up to 10⁴ cycles of loading were applied at a frequency of 0.2 Hz varying load amplitudes. The accumulated rotation of the bucket foundations increased with the number of cycles and the load amplitudes. Empirical equations were proposed to describe the accumulated rotation of the foundations. The unloading stiffness of foundations increased with the number of cycles but decreased with an increase in load amplitude. The initial unloading stiffness of L/D = 1.0 (L is skirt length; D is foundation diameter) was approximately twice that of L/D = 0.5. Excess pore water pressure difference of 50% was observed between L/D = 0.5 and 1.0. The suction and static capacity of the bucket increased with increase of bucket embedment ratio with a difference of 69.5% and 73.6% respectively between L/D = 0.5 and 1.0.     

空间互相关方法在分析海底沙波迁移规律中的应用

海底沙波具有显著的活动性并能够对海底工程设施造成潜在威胁,因此对海底沙波活动性的评估一直以来受到广泛关注。目前大多数研究者仍利用平面剖面对比来分析海底沙波的迁移特征。然而,该方法难以全面高效地获取海底沙波二维平面迁移矢量。本文基于2007年和2009年的高分辨率多波束测深数据,详细阐述了空间互相关方法在分析北部湾东南海域海底沙波迁移规律中的应用过程。利用实测数据进行对比分析,获得了研究区海底沙波的活动特征,并进一步讨论了空间互相关算法中不同参数的选取对结果的影响。结果显示,利用空间互相关分析方法能够有效获取海底沙波二维迁移矢量,获得的海底沙波迁移速率和迁移方向与前人研究成果吻合,表明了该方法的可行性和可靠性。但在对实际DTM数据进行空间互相关分析时,需根据海底沙波形态、数据质量等因素选取合适的参数及矢量获取方法。本研究实验了一种确定海底沙波迁移规律的新方法,该方法将有效提升获得海底地形变化规律的效率和准确度,可获得更加精细的海底地形动力过程。     

A finite element approach for predicting the full resistance profile of a spudcan deeply penetrating in dense sand overlying clay

This paper presents a finite element approach to calculate the full resistance profile of a spudcan deeply penetrating in dense sand overlying clay, in which a potential for an installing spudcan to experience a sudden uncontrolled punch-through failure exists. A modified Mohr-Coulomb model characterized by incorporating a four-phase variation of the mobilized strength and dilation parameters with an equivalent accumulated plastic strain is developed and tested for the overlying dense silica sand. An extended Tresca model is used for the strain softening of the underlying clay. A series of large deformation finite-element (LDFE) analyses are carried out, varying the strength and dilation parameters as well as the spudcan geometries. A fairly good performance of the present approach is verified by validating against groups of centrifuge tests data, allowing the numerical study to be extended parametrically. The four-phase variation of the mobilized strength and dilation parameters involved in the progressive failure of the upper dense sand is parametrically studied and extended to cover the range of sand relative densities that are of practical interest. Additionally, comparisons with the typical existing LDFE analyses using both simple and sophisticated constitutive models are carried out. It shows that the present approach performs fairly well to calculate the full resistance profile of a spudcan deeply penetration in both thin and thick dense sand overlying clay, especially the peak and post-peak resistance, within around 5% of the corresponding centrifuge tests results.     

海水海砂混凝土双K断裂参数的确定

采用尺寸为515 mm×100 mm×100 mm初始缝高比从0.1变化至0.8的三点弯曲梁试件,利用试验测得起裂荷载Pini、最大荷载Pmax及对应的裂缝口张开位移CMODc等参数,研究了缝高比a0/h对海水海砂混凝土双K断裂参数的影响。并以相同配合比的淡水河砂梁作为对照组,进一步研究了海砂海水混凝土双K断裂参数与普通混凝土之间的关系。结果发现海水海砂混凝土断裂参数在a0/h=0.25～0.7范围内时可以认为是一常数;海水海砂混凝土梁断裂参数比相同配合比情况下的淡水河砂梁大且对边界影响更加敏感。     

等效沙厚度研究进展

风、沉积物和地表覆盖是控制沙丘地貌的三大要素.沉积物尤其是沙源供应对沙丘地貌的影响仍有待深入研究.沙丘体积的研究促使了等效沙厚度(equivalent sand thickness,EST)概念的提出.EST研究经历了多个沙丘和亚沙丘尺度2个研究阶段.多个沙丘EST研究发现,EST与沙丘高度之间具有较好的一致性,其与方...