深水碎屑流与浊流混合事件层沉积特征及分布——以鄂尔多斯盆地西南长7油层组为例

采用岩石学、深水沉积学等方法,解剖野外露头及重点钻井岩心,结合测井、分析化验等资料,研究鄂尔多斯盆地西南延长组长7油层组深水碎屑流与浊流混合事件层的沉积特征及分布。结果表明:研究区长7油层组发育下部砂质碎屑流上部浊流混合事件层、下部浊流上部泥质碎屑流混合事件层(分为下部浊流上部富泥质碎屑和下部浊流上部贫泥质碎屑混合事件层)、泥质碎屑流和浊流频繁互层混合事件层3种类型。其中,下部砂质碎屑流上部浊流、下部浊流上部富泥质碎屑混合事件层发育于重力流沉积区的近端和远端,下部浊流上部贫泥质碎屑、泥质碎屑流和浊流频繁互层混合事件层主要分布于重力流沉积区的远端。研究区长7油层组深水重力流沉积具有近端呈条带状分布、水道化特征显著,远端相邻朵体沉积物相互叠置、连片、呈环带状分布的特征。该结果对完善深水重力流沉积理论及开展非常规油气勘探、开发具有指导意义。     

基于数字岩心技术的岩石孔渗特征研究: 以海外J油田孔隙型碳酸盐岩油藏为例

走向海外是解决我国能源安全问题的必由之路。但海外油气藏评价往往缺乏第一手岩心资料, 使得储层孔隙结构和渗流规律认识不清, 影响评价效果。以海外J油田孔隙型碳酸盐岩油藏为例, 应用数字岩心技术开展油气藏孔渗特征研究。①以不同流动单元的铸体薄片图像作为输入数据, 经过中值滤波和阈值分割预处理后, 基于马尔科夫链蒙特卡洛数值重构算法构建数字岩心; ②分析孔喉分布、孔喉连通性、孔隙度特征; ③基于格子玻尔兹曼模拟方法开展单相和油水两相流动模拟, 计算数字岩心的绝对渗透率和相对渗透率曲线。结果表明, 构建的三维数字岩心能够刻画不同流动单元孔隙型碳酸盐岩的孔喉半径分布及孔喉连通程度的差异化特征。数字岩心孔隙度与铸体薄片孔隙度吻合度高, 数字岩心渗透率与真实岩心渗透率存在较好的正相关关系, 且符合真实岩心所属的流动单元。油水两相稳态流动模拟计算的相对渗透率曲线体现了不同流动单元的两相渗流能力差异, 可作为数值模拟输入条件, 以及估算油藏采收率。数字岩心分析与物理实验结果吻合良好, 证明了该方法的可靠性。为岩心资料稀缺条件下油气藏表征和渗流特征分析提供新的思路, 对油气藏精细描述具有重要的参考价值。      

碳酸盐岩古溶洞层级约束地质建模方法探讨:以塔河油田奥陶系某缝洞单元为例

碳酸盐岩地下古溶洞及其内部充填结构一直以来是地质建模的难点。综合地震、地质、测井等资料,提出了溶洞复合体、单一溶洞及溶洞内部充填结构3个层次逐级约束建模的思路,探索了基于多点地质统计学的溶洞内部充填结构建模方法。其中溶洞复合体属于较大尺度地质体单元,地震分辨率基本可识别,井震联合反演约束下采用截断高斯模拟方法建立溶洞复合体模型;单一溶洞是溶洞复合体的重要组成单元,属于中等尺度地质体单元,地震分辨率难以直接识别,基于大量露头实测数据,在溶洞复合体约束下采用基于目标的方法建立单一溶洞分布模型;溶洞内部充填结构属于小尺度地质体单元,地震分辨率很难识别,在单一溶洞约束下,尝试采用多点地质统计学方法建立溶洞内部充填结构模型。以上层级约束建模思路有助于提升地下古溶洞及其内部储集体地质建模的准确度,在塔河油田某缝洞单元测试中取得了初步效果,同时讨论了存在问题及攻关方向。该研究对于精细表征缝洞型碳酸盐岩油气藏具有指导和启示作用。      

地质模式约束的SVR属性融合在浅水三角洲储层描述中的应用: 以西湖凹陷X气田为例

X气田位于东海盆地西湖凹陷中央反转构造带,主要目的层H4层为浅水三角洲沉积环境,气田地震资料主频较低（25 Hz）,而H4层埋深较大（3 300~3 400 m）,储层低孔低渗,常规地震反演预测砂体厚度吻合度较低。针对X气田三维地震资料全覆盖及钻井较少的特点,通过地质模式指导下的正反演结合设置虚拟井来弥补SVR（Support Vector Regression）算法中样本点的不足,通过提取地震属性并优选表征砂体厚度的敏感属性,利用SVR算法进行多属性融合,完成了H4层砂体的定量预测。基于储层预测成果,提出H4层为浅水三角洲曲流型分流河道沉积,并进一步完成了砂体沉积模式解剖,成功指导了开发调整井部署,实钻砂体厚度与预测砂体厚度吻合度高达84%以上。探索得到了海上少井条件下地质模式约束的SVR算法储层定量预测方案,对X气田中深层分流河道储层完成了精准预测,亦对同类型油气田的储层描述具有一定指导意义。      

Application of seismic interferometric migration for shallow seismic high precision data processing: A case study in the Shenhu area

The stability of submarine geological structures has a crucial influence on the construction of offshore engineering projects and the exploitation of seabed resources. Marine geologists should possess a detailed understanding of common submarine geological hazards. Current marine seismic exploration methods are based on the most effective detection technologies. Therefore, current research focuses on improving the resolution and precision of shallow stratum structure detection methods. In this article, the feasibility of shallow seismic structure imaging is assessed by building a complex model, and differences between the seismic interferometry imaging method and the traditional imaging method are discussed. The imaging effect of the model is better for shallow layers than for deep layers because coherent noise produced by this method can result in an unsatisfactory imaging effect for deep layers. The seismic interference method has certain advantages for geological structural imaging of shallow submarine strata, which indicates continuous horizontal events, a high resolution, a clear fault, and an obvious structure boundary. The effects of the actual data applied to the Shenhu area can fully illustrate the advantages of the method. Thus, this method has the potential to provide new insights for shallow submarine strata imaging in the area.     

地震沉积学在河流-浅水三角洲沉积相研究中的应用: 以渤海海域蓬莱A构造区馆陶组为例

庙西南凸起蓬莱A构造区馆陶组有良好油气发现,但储层厚度多小于5 m,难以被精确识别刻画。以薄层砂体为研究对象,综合地震、测井、钻井岩心、古生物等基础资料,明确研究区馆陶组沉积时期受北东向物源供给沉积,发育河流-浅水三角洲相。基于90°相位化处理确定砂体地震响应特征;分频解释处理判断相对等时地震同相轴,构建馆陶组高频层序地层格架（三级层序SQ1-3）,优选60Hz地震数据体进行地层切片划分;地层切片高精度沉积学解释揭示研究区馆陶组SQ1层序至SQ3层序依次发育河流-席状化浅水三角洲-朵叶状浅水三角洲-水下河道型浅水三角洲。其中SQ1层序中河道砂体以及SQ2-3层序中浅水三角洲前缘砂体皆为有利储层。此次研究丰富发展了渤海海域河流-浅水三角洲相中地震沉积学在砂体预测中的研究成果。      

Estimation of sediment load and erosion of different geological units: A case study from a basin of north-eastern Iran

Erosion of geological units and sediment load in rivers can be considered as the serious problems in recent decades.Increasing sediment loads generate major hazards for water resources development,particularly in terms of loss of reservoir storage due to sedimentation and siltation of water distribution systems.In this paper,the performance of four sediment rating curve (SRC) development methods was evaluated for the Shirin Darreh River(SDR) basin (1750 km2),located in North Khorasan Province,Iran.Data of flow discharge (Q) and suspended sediment flux (SSF)(Q-SSF pairs,N=957)and daily flow discharge,recorded by the Regional Water Company of North Khorasan (RWCNK) at the Qaleh-Barbar (QB) gauging site during 1989-2018were used.The flow discharge classification method performed best by meeting the desired criteria of most statistical indices,including normalized root mean square error (NRMSE),mean bias error (MBE),mean absolute error (MAE),index of agreement (d),and coefficient of determination (R~2).Based on the optimized method,the rate of suspended sediment transportation at the study site was estimated about2.7×10~6 ton year~(-1).Erodibility of the exposed formations in the study area was estimated based on a factorial scoring model (FSM).Three indices,focused on the outcrop and erodibility,were calculated for the geological units at sub-basin and total scales.Marl deposits are the most extensive geological unit in the three sub-basins and the maximum formation outcrop ratio (FOR) and participation in erosion (PCE)were obtained for these rocks at total scale.In fact,marl unit can be regarded as the main source to supply the suspended sediments in the study basin.     

Impact of anthropogenic activities on vegetation dynamics in a reservoir area: model establishment and a case study of Longkaikou Reservoir in China

Vegetation in hot and arid valleys is a crucial indicator of ecosystem health, but is vulnerable to human activities and environmental change. Using the Longkaikou Reservoir in the Jinsha River in southwestern China as a case study, we developed a spatially explicit model that combined the plant growth, fruiting, seed dispersal, and seed germination stages to reveal the potential impact of multiple human activities(reservoir construction, logging, grazing, and aerial seeding) on the vegetation dynamics of Dodonaea viscosa and Pinus yunnanensis. After reservoir construction, the grassland area of 68 km~2 in 2003 decreased to 24 km~2 in 2018, replaced by forest, shrubland, and bodies of water, and the precipitation increased during the dry season, which indicated the improvement of the local plant and soil environment. Our model predicted that when soil moisture decreased by more than 20% compared to current levels, the area of D. viscosa increased greatly at low elevations; however, when at higher soil moisture, P. yunnanensis would occupy more of the study area. Logging and grazing would slightly change the spatial pattern of vegetation and delay P. yunnanensis communities from achieving stability by directly reducing plant biomass. Countermeasures such as aerial seeding would increase the total area by 13.13 km~2 and 8.09 km~2 of two plants, respectively, and accelerate the stabilization of plant communities. The effects of multiple human activities on vegetation may counteract each other; for example, logging decreased the P. yunnanensis area whereas aerial seeding increased it, and plant biomass changed in response to this pressure. Given the complex relationships between vegetation and human impacts, our study provides a scientific basis for vegetation restoration and ecological security in this hot and arid valley.     

时频电磁井震联合建模反演探测深部火山岩储层内幕结构: 渤海湾盆地LD地区实例研究

盆地深部火山岩储层地震受能量屏蔽影响反射杂乱,使得火山岩油气藏的勘探非常困难。针对深部火山岩储层多期叠置的复杂内幕结构,研究了最优偏移距、激发周期窗口的时频电磁采集技术和时频电磁井震联合建模反演及电性节律变化火山岩期次解释技术,有效提高了该方法的深层分辨率和对深层目标的识别能力。在渤海湾盆地LD地区的研究应用效果明显,结果揭示红星构造带沙三段火山岩喷发自下而上表现出"弱-强-强-弱-弱"的"两强三弱"的特征,发育两个火山岩喷发机构,共同控制了5个期次的火山岩储层相带分布;桃园构造带沙三段各期次火山岩喷发强度明显减弱,仅发育一个火山岩喷发机构,除期次3火山岩储层相带分布范围相对较大外,其他期次火山岩主要局限分布于火山口附近,以爆发相为主,规模明显减小。后续钻探结果证实时频电磁揭示的火山岩储层分布正确,并为该区油气大发现提供了有力支撑,为探测类似的复杂目标提供了成功范例与技术方法。      

Engineering geological assessment for route selection of railway line in geologically active area: A case study in China

The Cheng-Lan railway links Chengdu, a central city in Southwestern China, and Lanzhou, a central city in Northwestern China. The railway passes through the Longmenshan fault zone (Wenchuan earthquake happened there on May 12, 2008), Minjiang fault zone, and Dongkunlun fault zone, which are all active. It runs over the Yangtze River and the Yellow River, and crosses high mountains and deep valleys. There exists, along the railway’s alignment, different kinds of strata of hard granite and soft, weak metamorphic rocks such as carbonaceous slate, schist, and phyllite. It is, therefore, a key issue for such an infrastructure construction to assess the engineering geological conditions and risks, so as to mitigate or avoid possible georisks and to offer optional designs. Geological survey and georisk assessment along the railway corridor are carried out. Special attention is given to active faults, earthquakes and seismic zones. Based on these, discussions about geological aspects for route selection of the railway are conducted and countermeasures for georisk control are proposed accordingly. Main conclusions are achieved as follows: (1) Geohazards such as landslides, rockfalls and debries flows dominate both the route selection of the railway and the engineering structures (e.g., tunnels or bridges) adopted; (2) Tunnel has been proved to be an excellent structure for linear engineering in geologically active area; and (3) In the case where avoiding is impractical, necessary protection measures should be taken to engineering slopes in high earthquake intensity areas, especially the area with earthquake of Ms. 8 or greater.