柴西北缘花土沟地区新近系油砂山组沉积特征及铀源分析

柴北缘花土沟地区新近系油砂山组含铀岩系为绿灰色碎屑岩沉积建造。区域内主要发育扇三角洲、滨浅湖相。含铀岩系受滨浅湖相沉积体系控制。研究区内铀源具有多源性特点,基底和盖层铀丰度较高。通过野外调查实测剖面和编录铀矿调查钻孔发现油砂山组具有泥-砂-泥结构特征,砂层厚度适宜,倾角较缓,属于宽缓的山前斜坡带,有利于含矿砂体及富氧流体进入层间,形成层间氧化带及铀的富集。     

临夏盆地新近纪郭泥沟剖面磁组构特征及其环境意义

临夏盆地在东亚新生代地层、古气候、古生物研究方面占有举足轻重的地位.本文对盆地东部的郭泥沟剖面进行了详细的岩石磁学和磁组构研究，以揭示从早中新世到早上新世临夏盆地的沉积演化过程.郭泥沟剖面沉积物中的磁性矿物有磁铁矿、磁赤铁矿、赤铁矿和针铁矿，但剩磁载体以磁铁矿和赤铁矿为主.从上庄组和东乡组的褐红色粉砂质粘土到柳树组和何王家组的褐黄色粘土，赤铁矿含量呈现降低的趋势，与沉积物颜色变化一致.郭泥沟剖面沉积物磁组构类型为正常沉积磁组构.结合岩石磁学结果和磁组构参数特征可揭示临夏盆地早中新世-早上新世沉积的演化过程：早中新世上庄组为稳定湖相沉积，古水流方向为NNW，与南北向的大夏河方向一致；中中新世气候发生较明显的干湿波动，形成了东乡组的褐红色湖相粉砂质粘土夹粉砂、砂和青灰色泥灰质粘土条带，古水流方向主要为NNW，沉积过程主要受大夏河控制；中中新世晚期，受青藏高原构造运动影响，沉积相由湖相细粒沉积物转变为虎家梁组河流相砂砾层；同时，盆地的水动力条件也发生改变，晚中新世柳树组湖相沉积过程同时受南北向大夏河和东西向洮河控制，两个方向近垂直的河流共同作用导致柳树组内沉积各向异性度较低，面理和线理均不发育，磁化率最大轴偏角分布比较分散，磁组构确定的古流向为东西向和南北向；早上新世期间，由于受青藏高原隆升影响，沉积了何王家组下部的河流相砂砾层；受构造抬升影响，大夏河重新主导何王家组上部洪泛平原相沉积过程，水动力条件较为单一稳定，古流向主要为N向，与大夏河流向一致.     

渤海湾盆地黄河口凹陷新近系油气富集模式与成藏主控因素定量评价

长期以来油气成藏定量研究是油气勘探研究的难点。文章基于三维地震、测井以及录井等资料，对渤海湾盆地黄河口凹陷新近系油气成藏条件、富集模式和成藏主控因素进行了系统研究。指出黄河口凹陷新近系油气主要富集在走滑反转带和断隆带两类构造单元，具有两种不同的成藏模式。其中，走滑反转带新近系的油气运移能力受油源断层的活动强度和古近系区域盖层厚度共同控制；断隆带新近系油气运移的能力受仓储层的输导脊和切仓断裂共同控制。并建立了两类不同成藏模式下表征油气输导能力的定量模型和公式。进一步指出，新近系构造-岩性圈闭在具备供烃条件时，其成藏规模仍受到“断-砂”接触程度的控制。砂体与油源断层的总接触面积越大，其内部油气充满度一般越高。     

Tectonostratigraphic framework and depositional history of the deepwater Ulleung Basin,East Sea/Sea of Japan

The Ulleung Basin, East Sea/Japan Sea, is a Neogene back-arc basin and occupies a tectonically crucial zone under the influence of relative motions between Eurasian, Pacific and Philippine Sea plates. However, the link between tectonics and sedimentation remains poorly understood in the back-arc Ulleung Basin, as it does in many other back-arc basins as well, because of a paucity of seismic data and controversy over the tectonic history of the basin. This paper presents an integrated tectonostratigraphic and sedimentary evolution in the deepwater Ulleung Basin using 2D multichannel seismic reflection data. The sedimentary succession within the deepwater Ulleung Basin is divided into four second-order seismic megasequences (MS1 to MS4). Detailed seismic stratigraphy interpretation of the four megasequences suggests the depositional history of the deepwater Ulleung Basin occurred in four stages, controlled by tectonic movement, volcanism, and sea-level fluctuations. In Stage 1 (late Oligocene through early Miocene), syn-rift sediment supplied to the basin was restricted to the southern base-of-slope, whereas the northern distal part of the basin was dominated by volcanic sills and lava flows derived from initial rifting-related volcanism. In Stage 2 (late early Miocene through middle Miocene), volcanic extrusion occurred through post-rift, chain volcanism in the earliest time, followed by hemipelagic and turbidite sedimentation in a quiescent open marine setting. In Stage 3 (late middle Miocene through late Miocene), compressional activity was predominant throughout the Ulleung Basin, resulting in regional uplift and sub-aerial erosion/denudation of the southern shelf of the basin, which provided enormous volumes of sediment into the basin through mass transport processes. In Stage 4 (early Pliocene through present), although the degree of tectonic stress decreased significantly, mass movement was still generated by sea-level fluctuations as well as compressional tectonic movement, resulting in stacked mass transport deposits along the southern basin margin. We propose a new depositional history model for the deepwater Ulleung Basin and provide a window into understanding how tectonic, volcanic and eustatic interactions control sedimentation in back-arc basins.     

A Late Miocene Paratethyan mollusc fauna from the Denizli Basin (southwestern Anatolia, Turkey) and its regional palaeobiogeographic implications

We report on a Late Miocene mollusc fauna from a single locality in the Denizli Basin in southwestern Turkey that is composed of ten presumably euryhaline species and three freshwater species. The fauna is remarkably distinct from faunas of the adjacent Late Miocene Aegean and Euxinian Basins, and has elements in common with the modern Caspian Sea fauna in the form of Didacna species. The suggested age of the fauna (Late Miocene) would extend the stratigraphic range of the lymnocardiid genus Didacna (hitherto Calabrian-Extant) considerably. The palaeobiogeographic significance of the Denizli fauna is discussed.     

GEOPHYSICAL CHARACTERIZATION OF THE SANGU GAS FIELD,OFFSHORE, BANGLADESH: CONSTRAINTS ON RESERVOIRS

The only produced offshore gas field in Bangladesh, known as the Sangu field, is located in the Hatiya Trough in the east of the Bay of Bengal, and has estimated total reserves of about 1055 BCF GIIP. The early shut-down of the field in October 2013 may have resulted in significant volumes of recoverable gas being left in the subsurface over a depth range of 1893 m to 3640 m. In this paper, seismic and well log data were analyzed and interpreted in order to investigate the structure and stratigraphy of the Sangu field, together with the lithology, extent and petrophysical properties of the reservoir. The general lithostratigraphy at Sangu has some similarity to that of the Surma Basin of the Bengal Foredeep. Reservoir rocks consist of Miocene and Pliocene deltaic sandstones and deep-water clastics. The source rock is the Miocene Bhuban Shale which is mature for gas generation in the Hatiya Trough. Three Neogene seismic stratigraphic megasequences were recognised at Sangu and are interpreted to have been deposited respectively in fluvial, delta front and shelf slope or marginal marine settings. Based on an analysis of wireline logs from wells Sangu-1 and Sangu-5 and on seismic-to-well ties, a series of reservoir units referred to (from the base up) as the T1 (E, D, C, A&B), Supra-T1, T2 and T3 have been identified. Petrophysical analyses showed that the average total porosity of these reservoir units is >13%, the permeability is in general less than10 mD, and the gas saturation ranges from 24% to 80%. Mapping of the reservoirs shows that the structure at Sangu is an asymmetric anticline with a NNW-SSE axial trend. Amplitude data have allowed the delineation of two other potential reservoir zones in the field at depths of 2900-3000 m and 3550-3750 m. The study will contribute to future offshore gas exploration and development in the Bay of Bengal region based on the geological and geophysical characteristics of the reservoirs delineated.     

渤海湾盆地沙垒田地区新近纪走滑断裂发育特征及其对油气富集的控制作用

沙垒田凸起地区是渤海海域西部新近系油气最为富集的区域，为了明确新近系走滑断裂发育特征及对油气富集的控制作用，依托连片高精度三维地震、钻井取心等资料，对走滑断裂类型及发育特征进行了详细刻画，并对走滑断裂与成藏要素之间的关系进行了探讨。综合研究表明：研究区发育断穿基底走滑断裂、盖层走滑断裂及伸展-走滑断裂三种不同类型走滑断裂；走滑断裂对圈闭的控制作用表现为在不同类型走滑断裂控制下，断裂带内及断裂带间形成了多种类型圈闭，其中大型披覆背斜圈闭、断鼻、断背斜圈闭为有利圈闭，小型断块圈闭为不利圈闭；走滑断裂对输导体系的控制作用体现在断裂活动控制了骨架砂体输导体系及断裂输导体系的形成发育，有利于周边凹陷成熟烃源岩排烃及运移输导；走滑断裂对储层的控制作用表现为走滑作用形成的高角度裂缝提高了储层渗透率，改善了储层物性。新近纪普遍发育的走滑断裂是研究区油气富集的主控因素。     

埕岛地区中浅层河流相砂体输导性研究——以渤海海域埕岛地区新近系为例

河流相砂体是埕岛地区中浅层主要的油气输导层和储集层,研究其输导性对油气勘探具有重要意义。研究认为,断层相连是中浅层河流相砂体输导油气的前提,构造背景影响着油气输导方向;河道沉积砂体输导性最好,堤岸沉积砂体次之,泛滥平原沉积的砂体最差。不同岩性中细砂岩输导性最好,中砂岩次之,粉砂岩第三;输导砂体物性下限随着埋深增加而减少;砂体连通性越好,输导性越好。根据砂体宏观连通基本类型,建立了厚砂体直接连通型、微断层连通型和薄砂体或物性较差砂体连通型三种输导模式,并提出中浅层河流相砂体输导性的评价思路。     

Desmaninae (Talpidae, Mammalia) from the Pliocene of Tollo de Chiclana (Guadix Basin, Southern Spain): Considerations on the phylogeny of the genus Archaeodesmana

The fossil Desmaninae (water-moles) from the Pliocene continental deposits of Tollo de Chiclana (Guadix Basin, Southern Spain) are described. A new species, Archaeodesmana elvirae, is defined from the locality of Tollo de Chiclana-1 (upper Ruscinian). This species is characterized by relatively small canines and premolars (except the P4) and large P4 and molars, besides several morphological features. The presence of Archaeodesmana brailloni is reported from the locality of Tollo de Chiclana-1B (uppermost Ruscinian). A small sample assigned to the genus Archaeodesmana is described from the lower Villafranchian site of Tollo de Chiclana-3, which cannot be determined at the specific level. The phylogenetic relationships between the different species of Archaeodesmana are reconsidered in the light of the recent findings, which support the idea of a more complex phylogeny than previously proposed for this genus. The populations from the Guadix Basin, previously assigned to Dibolia dekkersi (= Archaeodesmana getica), are here considered to belong to a different (unnamed) species, which is the ancestor of A. elvirae. On the other hand, the new species A. elvirae is proposed as the ancestor of A. brailloni.     

准噶尔盆地车排子北部地区沙湾组碳酸盐胶结物差异性分布控制因素

通过铸体薄片、AxioVision图像分析、岩芯常规分析、地层水测试等方法,在明确了碳酸盐胶结物类型的基础上,采用多方法进行了碳酸盐胶结物含量的测定,探讨了准噶尔盆地车排子地区北部沙湾组碳酸盐胶结物差异性分布控制因素,并揭示了其对储层物性、油水分布的影响。研究表明,车北地区沙湾组储层中发育大量的早期碳酸盐胶结物,不均匀充填部分原生粒间孔,具有强烈的非均质性;在岩芯常规测定碳酸盐胶结物含量的基础上,利用多次数、多视域的AxioVision图像分析补充测定了碳酸盐胶结物含量,与岩芯常规测定结果对比相对误差-0.14,弥补了数据点的不足。碳酸盐胶结物含量平面上具有"北高南低"的差异性分布特征,胶结物形成于封闭性好、水体交替停滞的还原环境中,地层水Ca~(2+)含量的差异决定了碳酸盐胶结物分布的差异,而地层水Ca~(2+)含量的差异主要受古地貌控制,古高地水体较浅易富集Ca~(2+)是CaCO_3沉淀的良好场所,沉积微相在局部井区起到一定的控制作用。碳酸盐胶结物差异性导致研究区储层物性具有"双峰值"特征,并造成了高黏超稠油油藏复杂的油水分布关系。