Structural-stratigraphic control on the Umitaka Spur gas hydrates of Joetsu Basin in the eastern margin of Japan Sea

Integrated geological, geochemical, and geophysical exploration since 2004 has identified massive accumulation of gas hydrate associated with active methane seeps on the Umitaka Spur, located in the Joetsu Basin on the eastern margin of Japan Sea. Umitaka Spur is an asymmetric anticline formed along an incipient subduction zone that extends throughout the western side of the Japanese island-arc system. Seismic surveys recognized chimney structures that seem strongly controlled by a complex anticlinal axial fault system, and exhibit high seismic amplitudes with apparent pull-up structures, probably due to massive and dense accumulation of gas hydrate. Bottom simulating reflectors are widely developed, in particular within gas chimneys and in the gently dipping eastern flank of the anticline, where debris can store gas hydrates that may represent a potential natural gas resource. The axial fault system, the shape of the anticline, and the carrier beds induce thermogenic gas migration to the top of the structure, and supply gas to the gas hydrate stability zone. Gas reaching the seafloor produces strong seepages and giant plumes in the sea water column.     

倾角导向体控制的气烟囱识别技术及其在海拉尔盆地贝尔凹陷中的应用

在调研了国内外气烟囱研究成果与思路的基础上,通过全新的地震解决方案——OpendTect平台提供的基于属性多层感知器(MLP)的人工神经网络(ANN)的方法预测气烟囱的发生概率体,并利用倾角导向体对算法进行改进,提出倾角控制下的地震气烟囱识别技术,很好地补充并发展了模式识别技术在地震勘探领域的应用。通常该技术一方面可以解释运移通道和浅层气成藏的原因;另一方面,形成的气烟囱地震数据体还可以预测源岩的发育情况;此外,对于判别断层封闭性也非常适用。最后应用这一技术对海拉尔盆地贝尔凹陷一含油区块的运移通道和成藏规律进行研究,分析该研究区的断裂发育特征和运移通道类型,总结了油源、通道、储层和盖层的空间配置关系,并建立相应的成藏模式。     

南海南部陆缘地质流体类型及其油气成藏意义

南海南部陆缘蕴藏着非常丰富的油气资源。为了解南海南部陆缘流体活动系统以及与油气藏之间的关系,以高精度2D地震资料为基础,对南海南部陆缘流体活动系统的类型、地震反射特征、以及对油气成藏的意义开展了研究。在南海南部陆缘发现了多种流体活动系统,包括:泥底辟/泥火山、气烟囱、管状通道、与构造断层相关的流体活动系统。这些流体活动系统具有不同的地震反射特征,常常出现含气强振幅异常带、弱振幅杂乱反射带以及"下拉"或者"上拱"地震反射形态等流体活动系统的标志特征。流体活动系统受到构造运动和沉积因素的影响,并且与深部高温高压塑性流体密切相关,流体活动系统优先发育在地层薄弱部位。流体活动系统及所伴生的断裂和裂隙常常作为油气富集区的运输通道;并且流体活动系统所运移的强溶蚀性流体和深部热液流体有利于油气储层的形成,特别是对于碳酸盐岩储层的改造尤为明显。因此,流体活动系统不仅能作为油气运移通道,也可以改善储层,对油气成藏具有重要意义。     

新疆哈密坡子泉地区首次发现隐爆角砾岩筒

新疆哈密坡子泉地区首次发现的隐爆角砾岩筒处在塔里木板块北缘活动带卡瓦布拉克微板块之上,基底地层为前寒武系,盖层主要为石炭系,受ＮＥ向断裂带控制。隐爆角砾岩特征及产出环境相似于金伯利岩。     

570矿床控制因素及富矿形成条件

570矿床地质背景是破火山旋回边缘活动带;矿床定位要素是受破火山断裂系统构造结控制的隐爆角砾岩筒;隐爆加断陷组成的聚矿结构,是富矿形成的主要条件;隐爆角砾岩筒与次火山花岗岩浆侵位组成的热泵汲取效应,是矿床基本成因模式。矿床扩大方向是在探索隐爆角砾岩筒深部的同时,沿边缘活动带,在破火山断裂系统构造结处寻找新的隐爆角砾岩筒。     

Myojin Rift, Izu–Bonin Arc as the Modern Analog of Hokuroku Basin, Northeast Japan: Geotectonic Significance of the New Hydrothermal Deposit in the Back-Arc Rift

A huge hydrothermal field, named the "Hakurei Sulfide Deposit" (HSD) was discovered in the North Myojin Rift (NMR), Izu–Bonin Back-Arc Rift (BAR) during the 2003 survey cruise of R/V Hakurei-maru No.2 . This paper investigates the geotectonic features and the tectonic setting of ore deposits between the NMR and the Hokuroku Basin, which is representative of kuroko fields in Japan. The topographic features of the NMR and the Hokuroku Basin are similar. Both have a clear ring structure surrounded by faults and the east–west width is almost the same. Many kuroko deposits were formed on the extrusion centers of the five pre-mineral acidic volcanic complexes, located in a loop inside the Hokuroku Basin. In the case of the NMR, seven submarine volcanoes are also located in a loop, and the HSD formed inside the summit caldera of Bayonnaise Knoll, which is one of the seven volcanoes. These topographic similarities highlight that the NMR is a modern analog of the Hokuroku Basin. Identifying such similarities is extremely useful when prospecting kuroko deposits on land equivalents as well as on the other segments of the Izu–Bonin BAR. The probability of finding kuroko deposits on land is expected to increase when the following are identified: (i) location of back-arc rift and the volcanic front; (ii) direction of the arc–trench system and intra-rift faults (and/or fracture zone); (iii) position of submarine volcanoes surrounding a back-arc rift; and (iv) intersections of a caldera fault and intra-rift fault (and/or fracture zone) inside the summit caldera of submarine volcanoes. Within these aforementioned points a ring structure, acidic volcanic complexes that circle the circuit and submarine calderas along the volcanic front, are an important indication of submarine hydrothermal deposits.     

台湾岛东北部龟山岛附近海域自然硫烟囱体的基本特征研究

龟山岛热液活动区位于冲绳海槽向西延伸的部位，菲律宾海板块向欧亚板块下方俯冲在此隐没，热液活动的出现为研究该地区进一步的发展提供了契机．龟山岛热液活动产生的烟囱体高度富集自然硫，几乎没有其它矿物结晶形成，烟囱体本身呈现分层现象，自然硫的含量也是从烟囱体的外层到内层依次增高，与烟囱体颜色上表观的分层呈现良好的对应关系．我们根据这种分层现象探讨了烟囱体的成因机制和热液流体随时间的变化特征，同时根据等离子质谱（ICP-MS）和X射线衍射仪（XRF）的实验数据分析了自然硫烟囱体存在两种物质来源：热液活动区基底的安山岩和地幔，但是对于地幔物质以何种形式加入到热液流体中还需进一步研究．     

用图像处理技术研究油气田的航磁航放异常

用图像处理技术对下述与油气田异常有关的问题进行了研究：快速提取高频弱磁异常，估算高频磁异常源的埋深，放射性异常性质的归一化处理，典型异常剖面的分析，以及油气远景评价，提出了４个有希望含油气的异常．经验证，这４个异常中有３个见到油气显示，其中１个为工业气流．     

地下开采对电厂烟囱的影响预测分析

结合具体工程项目,分析了各种因素对大型高耸烟囱的影响,介绍了烟囱允许倾斜值的理论和经验计算方法,为评价和预测烟囱的稳定性提供了理论依据和实用的计算方法。     

The formation mechanism of mud diapirs and gas chimneys and their relationship with natural gas hydrates: insights from the deep-water area of Qiongdongnan Basin,northern South China Sea

ABSTRACT

Mud diapirs and gas chimneys are widely developed in continental slope areas, which can provide sufficient gas for hydrate formation, and they are important for finding natural gas hydrates. Based on the interpretation and analysis of high-resolution 2D and 3D seismic data covering the deep-water area in the Qiongdongnan Basin (QDNB), northern South China Sea, we studied the formation mechanism of mud diapirs and gas chimneys and their relationship with natural gas hydrates. Mud diapirs and gas chimneys are columnar and domelike in shape and the internal regions of these bodies have abnormal reflections characterized by fuzzy, chaotic, and blanking zones. The reflection events terminate at the rims of mud diapirs and gas chimneys with pull-up reflections and pull-down reflections, respectively. In addition, ‘bright spots’ and diapiric-associated faults occur adjacent to mud diapirs and gas chimneys. The rapidly deposited and deeply buried fine sediments filling in the Tertiary in deep-water areas of the QDNB and overpressure potential derived from undercompacted mudstones, as well as from the pressurization of organic matter and hydrocarbon generation, provide abundant materials and intensive driving forces for the formation of mud diapirs and gas chimneys. Bottom simulating reflectors (BSRs) with strong amplitude and high or poor continuity were recognized atop the mud diapirs and gas chimneys and in the structural highs within the same region, indicating that they have a close relationship with each other. The mud diapirs and gas chimneys and associated high-angle faults provide favourable vertical pathways for the hydrocarbons migrating from deep strata to shallow natural gas hydrate stability zones where natural gas hydrates accumulate; however, some BSRs are characterized by weak amplitude and poor continuity, which can be affected by high temperature and overpressure in the process of the mud diapir and gas chimney activities. This mutually restricting relationship must be taken into consideration in the process of gas hydrate exploration in QDNB.