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21.
Focused fluid flow in the Baiyun Sag, northern South China Sea: implications for the source of gas in hydrate reservoirs 总被引：1，自引：0，他引：1
The origin and migration of natural gas and the accumulation of gas hydrates within the Pearl River Mouth Basin of the northern South China Sea are poorly understood. Based on high-resolution 2D/3D seismic data, three environments of focused fluid flow: gas chimneys, mud diapirs and active faults have been identified. Widespread gas chimneys that act as important conduits for fluid flow are located below bottom simulating reflections and above basal uplifts. The occurrence and evolution of gas chimneys can be divided into a violent eruptive stage and a quiet seepage stage. For most gas chimneys, the strong eruptions are deduced to have happened during the Dongsha Movement in the latest Miocene, which are observed below Pliocene strata and few active faults develop above the top of the Miocene. The formation pressures of the Baiyun Sag currently are considered to be normal, based on these terms: 1) Borehole pressure tests with pressure coefficients of 1.043–1.047; 2) The distribution of gas chimneys is limited to strata older than the Pliocene; 3) Disseminated methane hydrates, rather than fractured hydrates, are found in the hydrate samples; 4) The gas hydrate is mainly charged with biogenic gas rather than thermogenic gas based on the chemical tests from gas hydrates cores. However, periods of quiet focused fluid flow also enable the establishment of good conduits for the migration of abundant biogenic gas and lesser volumes of thermogenic gas. A geological model governing fluid flow has been proposed to interpret the release of overpressure, the migration of fluids and the formation of gas hydrates, in an integrated manner. This model suggests that gas chimneys positioned above basal uplifts were caused by the Dongsha Movement at about 5.5 Ma. Biogenic gas occupies the strata above the base of the middle Miocene and migrates slowly into the gas chimney columns. Some of the biogenic gas and small volumes of thermogenic gas eventually contribute to the formation of the gas hydrates. 相似文献
22.
深水盆地中多边形断层的几何特征与形成机制探讨 总被引：4，自引：0，他引：4
多边形断层是指一种在平面上呈多边形具有微小断距的张性断层系。自1994年被提出以来, 已有十余年的研究历史, 并在世界50多个被动大陆边缘盆地中被识别出来。研究多边形断层需要高精度的3D地震资料。我们根据琼东南盆地3D地震资料并利用相干切片技术, 首次在琼东南盆地南部发现了多边形断层, 并对其进行了初步研究。多边形断层的成因机制是前期多边形断层研究的重点, 许多学者认为深水沉积物早期压实脱水体积收缩形成的; 也有学者认为重力扩展控制断裂的发育。岩石物性、成岩作用及构造应力是影响多边形断层发育的重要因素。多边形断层对深水盆地的油气储集体的性质和分布; 以及油气、天然气水合物的运移和聚集有着重要的意义。 相似文献
23.
The experimental apparatus for gas hydrate in porous sediments is introduced.Under different constant temperature(1.0℃,2.0℃,4.0℃,7.0℃,10.℃),the formation and dissociation of methane hydrate with three kinde of sediments granule(average diameters 0.15mm,0.06mm,0.03mm respectively) are studied. The saturation of methane hydrate in porous sediments is got by measuring the consumption of methane in vesssel. The results find that the saturation increases as formation pressure and porosity of sediments increase. It is also showed that the P-T curve in distilled water,which is accordant with the results from other papets sediments departure to left comparing to the P-T curve in distilled water, which is accordant with the results from other papers involved . 相似文献
24.
将自适应量子遗传算法引入到地震定位中,通过多种数值试验证明了算法的有效性,同时也具有较强的全局搜索能力和抗噪能力.即使用于定位的台站数目较少且分布不理想,该算法通过多次反演求取平均值仍然能得到令人满意的结果.另外,利用多次数值试验估测的自适应量子遗传算法的定位精度较高,误差较小.将自适应量子遗传算法应用于山东省及邻区的地震重定位,均方根残差由重定位前的1.162s减小到重定位后的0.621s,重定位后的地震大多位于中上地壳,震源深度小于20km.通过对各剖面震源分布的分析,发现山东省及邻区地震主要受控于区域内的深大走滑断裂,且中强震多发生在高/低速异常体周围,尤以高低速异常过渡地带频发. 相似文献
25.
南海南部陆缘构造复杂多变,海底崎岖不平,造成该区多道地震资料多次波十分发育且混杂复杂绕射波。为了识别深层有效反射信息、压制多次波,首先通过正演模拟分析深水条件下多次波的传播规律和特征,然后对复杂理论Pluto模型进行详细处理并试验了几种典型多次波压制方法,寻找到一套有效的多次波压制处理思路:通过表面相关多次波衰减(SRME)法降低多次波能量级别,运用τ-p域预测反褶积压制周期规律的近中道多次波,再在此基础上灵活运用高分辨率抛物线Radon变换对共反射点道集(CRP)进行中远道多次波压制。理论模型和礼乐盆地海区的实际资料处理结果表明,该方法能够较大程度上压制深水资料多次波并增强对深部有效信息的识别。 相似文献
26.
Based on seismic and drilling data, we calculated tectonic subsidence amounts and rates of the Wan’an Basin by backstripping. The genetic mechanism and syn-rifting process of the basin were analyzed in combination with the regional geological setting. The results reveal that the basin syn-rifted in the Eocene and early Miocene under the control of the dextral strike-slip Wan’an Fault Zone. The transtensional/extentional stresses along this fault zone may be attributed to seafloor spreading of the South China Sea (SCS) in multiple episodes. Extensive basal faults and some small initial rifts in the early Paleogene can be related to southeastward extrusion and clockwise rotation of the Indochina Block. During the Oligocene, the nearly N-S directed spreading of the SCS derived the transtensional stresses in a roughly NW-SE orientation. The basin subsided rapidly in the middle and north to form two major subsidence centers. In the early Miocene, the SCS spread again in a nearly NW-SE direction, resulting in rapid subsidence in the southern basin continuous extending until the period ～16.3 Ma. 相似文献
27.
<正>岩石圈在水平拉张力的作用下会发生伸展变形,以致形成裂陷盆地,但是在多因素的影响下,岩石圈的拉张形式会存在很大的差异,因此学者致力于提出不同模型解释不同的裂陷盆地结构。英国学者Mc Kenzie根据大陆纯剪切伸展模式建立了岩石圈伸展量与裂陷盆地的沉降量以及后裂陷阶段热沉降量之间的定量模型[1],在解释被动大陆边缘的地壳减薄、张裂和沉降方面发挥了重要作用[2-3],但它仅适用于完全对称的纯剪拉张模型,很难解释非对称共轭 相似文献
28.
为了更有效地研究伸展盆地，论述了目前伸展盆地研究中几种常用软件的方法和原理，包括用于盆地反演研究的一维Airy均衡模型、二维挠曲回剥模型、平衡剖面技术以及用于盆地正演研究的挠曲悬臂梁模型和二维粘弹塑性热-力学数值模拟模型。综合分析了这些方法的原理、优势与不足，在此基础上进一步探讨了不同方法之间的综合运用。其中平衡剖面技术恢复得到的盆地剖面可以为裂谷期构造沉降展布范围提供约束，并与挠曲悬臂梁模型结合可以得到盆地演化过程中不同时期上地壳的伸展减薄情况。数值模拟方法则在以上盆地模拟方法得到的结果约束下，模拟伸展盆地的形成过程进而得到初始地质参数与演化过程。综合利用盆地分析的方法可以对盆地演化有更准确的认识并指导油气资源的勘探与开发。 相似文献
29.
琼东南盆地第四纪块体搬运体系的地震特征 总被引：4，自引：0，他引：4
第四纪以来,琼东南盆地的陆坡区域广泛发育深水块体搬运体系。深水块体搬运体系是广泛发生在外陆架/上陆坡的一种沉积物搬运机制,包括滑动、滑塌和碎屑流等重力流作用过程。利用深水3D地震资料,提取振幅和相干数据,通过地震剖面、构造图和时间切片分析,揭示块体搬运体系具有丘状外形、波状反射结构、弱振幅和连续性差的地震特征,内部整体比较杂乱,主体发育褶皱,趾部发育逆冲断层,具有塑性流体特征。结合南海构造背景分析,认为研究区第四纪沉积速率高并位于地震多发带,构成了块体搬运体系的形成条件和触发机制。 相似文献
30.
我国南海是西太平洋最大的边缘海，其北部陆缘盆地深水区位于琼东南与珠江口盆地南侧。通过对该地区烃源条件、储层奈件、圈闭条件及成藏模式等的初步研究，认为其具有良好的石油地质条件，有效勘探面积和勘探潜力巨大，具有良好的勘探前景。坎坡斯盆地位于巴西大西洋大陆边缘，是一个中生代到古新近纪含油气盆地，其内部的Garoupa，Carapeba，Namorado，Roncador，Marlim等深水油田的地质储量十分丰富，随着各个油田开发的深入，对该地区的深水含油气系统有了更加清晰的了解。本文通过两个地区在构造演化，烃源条件，储层条件，圈闭条件以及成藏模式的对比研究，对南海北部陆缘盆地深水区有了进一步的认识。 相似文献