Depositional architecture of the late Ordovician drowned carbonate platform margin and its responses to sea-level fluctuation in the northern slope of the Tazhong region, Tarim Basin

The Tazhong Uplift of the late Ordovician is a drowned rimmed carbonate platform. The carbonate rock of the late Ordovician Lianglitage Formation in the northern slope of the Tazhong region is one of the significant petroliferous intervals. Based on petrofacies, depositional cycles, natural gammaray spectrometry and carbon/oxygen isotope data from the Lianglitage Formation, one 2nd-order, three 3rd-order and several 4th-order sequences have been recognized, and the late Ordovician relative sealevel fluctuation curve has been established. The sequences O3 1-1 and O3 1-2 on the platform are composed of highstand and transgressive systems tracts, but lack the lowstand systems tract. The sequence O3 1-3 is a drowning sequence. The sequence O3 1-1 overlapped the eroded slope and pinched out to the northwest and landward. The highstand systems tract in the sequence O3 1-2 consists of low-angle sigmoid and high-angle shingled progradation configuration. Major sedimentary facies of the Lianglitage Formation include reef and shoal in the platform margin and lagoon, which can be subdivided into coral-sponge-stromatoporoid reef complex, sand shoal, lime mud mound, and intershoal sea. Reefs, sand shoals and their complex are potential reservoir facies. The reefs and sand shoals in the sequence O3 1-1 developed in the upper of its highstand systems tract. In the sequence O3 1-2, the highstand systems tract with an internal prograding configuration is a response to the lateral shifting of the complex of reef and sand shoal. The transgressive systems tract, in particular the sand shoals, developed widely on the slope of the platform margin and interior. The reefs in the sequence O3 1-3 migrated towards high positions and formed retrograding reefs in the western platform and low relief in the platform interior. Basinward lateral migration of the reefs and pure carbonate rock both characterize highstand systems tract and show that the rise of the relative sea-level was very slow. Shingled prograding stacking pattern of the 4th-order sequences and reefs grow horizontally, which represents the late stage of highstand systems tract and implies relative sealevel stillstand. Reefs migrating towards high land and impure carbonate rock both indicate transgressive systems tract and suggest that the relative sea-level rose fast. Erosional truncation and epidiagenetic karstification represent a falling relative sea-level. The relative sea-level fluctuation and antecedent palaeotopography control the development and distribution of reef complexes and unconformity karst zones. Currently, the composite zone of epidiagenetic karstic intervals and high-energy complexes of reefs and sand shoals with prograding configuration is an important oil and gas reservoir in the northern slope of the Tazhong carbonate platform.

Permian and Triassic Sequence Stratigraphy and Sea Level Changes of Eastern Yangtze Platform

The Permian and marine Triassic of eastern Yangtze platform, situated in eastern China, involve 19 orthosequences lasting about 2.7 Ma on average, which can be combined into five orthosequence sets ranging from 8 Ma to 12 Ma. Affected by the regional Dongwu and Indosinian movements, the sequence stratigraphic pattern and sea level changes in the Permian and Triassic of this region are distinctive and obviously different from most other regions in the world, but typical in the broad eastern Tethys and its neighboring areas. In this region not only did the continuous marine Permian and Triassic boundary sequences cause the orthosequence crossing the boundary belonging to type Ⅱ sequence but also the mesosequence including these stratigraphic intervals had its basal boundary in the upper Longlinian (Artinskian) (ca. 278 Ma), that is, the traditional Carboniferous and Permian boundary, and its top boundary moved from the Permian and Triassic boundary upward into the Anisian of Middle Triassic.

From Cycles to Sequences:Sequence Stratigraphy and Relative Sea Level Change for the Late Cambrian of the North China Platform

In the Late Cambrian, the North China Platform was a typical carbonate ramp platform. The Upper Cambrian of the northern part of the North China Platform is famous for the development of bioherm limestones and storm calcirudites and can be divided from bottom to top into the Gushan, Changshan and Fengshan formations. In this set of strata, the deep-ramp mudstone and marls and the shallow-ramp packstones and grainstones constitute many carbonate meter-scale cycles of subtidal type. More tidal-flat dolomites are developed in the Upper Cambrian of the southern margin of the North China platform, in which limestone and dolomite beds also constitute many carbonate meter-scale cycles of the peritidal type. These cycles are marked by a variety of litho-facies successions. There are regularly vertical stacking patterns of meter-scale cycles in long-term third-order sequences, which is the key to discerning such sequences. Third- order sequence is marked by a particular sedimentary-facies succession that is the result of the environment-changing process of deepening and shoaling, which is genetically related to third-order sea level changes. Furthermore, four third- order sequences can be grouped in the Upper Cambrian of the North China Platform. The main features of these four third -order sequences in the northern part of the platform can be summarized as follows: firstly, sequence-boundaries are characterized by drowning unconformities; secondly, the sedimentary-facies succession is generally constituted by one from deep-ramp facies to shallow-ramp facies; thirdly, a succession of “CS (?)+HST” (i.e., “condensed section and high- stand system”) forms these four third-order sequences. The chief features for the third-order sequences in the southern part of the North China Platform comprises: more dolomites are developed in the HSTs of third-order sequences and also developed more carbonate meter-scale cycles of peritidal types; the sedimentary-facies succession of the third-order sequences is marked by “shallow ramp-tidal flat”; the sequence boundaries are characterized by exposure punctuated surfaces. According to the changes for the third-order sequences from the north to the south, a regular sequence- stratigraphic framework can be established. From cycles to sequences, the study of sequence stratigraphy from litho-facies successions to sedimentary-facies successions exposes that as follows: meter-scale cycles that are used as the basic working unit actually are litho-facies successions formed by the mechanism of a punctuated aggradational cycle, and third -order sequences that are constituted by regularly vertical stacking patterns of meter-scale cycles are marked by sedimentary-facies successions. On the basis of the changing curve of water depth at each section, the curve of the relative third-order sea level changes in the late Cambrian of the North China Platform can be integrated qualitatively from changing curve of water depth. The correlation of Late Cambrian long-term sea level changes between North China and North America demonstrates that there are not only similarities but also differences, reflecting control of long-term sea level changes both by global eustacy and by regional factors.

Research on the seismic fortification level of offshore platform in Bohai Sea and adjacent areas

API code is introduced at first, and then a comparison of seismic character and seismic hazard between Bohai and Southern California is carried out. The analysis indicates both the seismic frequency and intensity and the seismic hazard of Bohai are much weaker than that of Southern California. API code states the strength level and deformation level of permanent structures in Southern California takes 200 a and several hundred to a few thousand years respectively. But in the reference codes in China, the seismic levels take 500 a and 10000 a for strength design and deformation design, and it seems too conservative. In China, the deformation level of class A structure takes 2%-3% probabilities of exceedance in reference period 100 a, and that of class B and C often takes 2%-3% in 50 a. Now that offshore platforms may cause server subsequent risk, it is safe to take 1% in 30 a as its deformation design level. On the basis of the above analyses and social economic level and the consistency with present codes, the strength design level and deformation design level of Chinese offshore platforms is suggested to take 200 a and 3000 a respectively.

Characteristics and distribution patterns of reef complexes on the carbonate platform margin in deep water areas:the western South China Sea

As a potential oil and gas reservoir, reef complexes have been a research focus from petroleum geologists for a long time. There are favorable conditions for the development of reef complexes in the South China Sea; however, their internal structures, evolution and distribution are still poorly understood. Based on 2D and 3D seismic data, the internal structures and evolution patterns of the reef complexes on the carbonate platform margin in the deep water areas over the western South China Sea were studied in detail. The result shows that two types of reef complexes, i.e., fault controlling platform margin reef complexes and ramp reef complexes have been developed in the study area. The reef complexes have independent or continuous mound or lenticular seismic reflections, with three internal structures （i.e., aggrading, prograding and retrograding structures）. There are different growth rates during the evolution of the reef complexes, resulting in the formation of catch-up reefs, keep-up reefs and quick step reefs. The study also reveals that different platform margin reef complexes have different internal structures and distributions, because of the different platform types. These results may be applied to the exploration and prediction of carbonate platform margin reef complexes in other areas that are similar to the study area.

Cambrian Sequence Stratigraphy and Sea Level Cycles of North China Platform

The Cambrian of the North China platform consists chiefly of shallow water deposits and shows the sedimentary characters of an epicontinental sea basin. Controlled mainly by global sea level changes and sedimentary influx, the depositional sequences all exhibit as composite sequences. From bottom upward, 14 sequences (3rd order) are recognized, which may be grouped into 5 sequence sets and further into 2 mesosequences (2nd order). It is suggested herein that the Cambrian/Ordovician boundary may better be set at the MFS (maximum flooding surface) of the sequence OSq1, above which the conodont Cordylodus lindstroemi occurs. This position is about 40 m above the traditional Cambrian/Ordovician boundary and is within the Yeli Formation.

福州市深远海养殖发展现状与建议

推进福州市深远海养殖发展,是缓解近海养殖环境压力、优化海水养殖空间布局、保障水产品有效供给、促进福州市海水养殖业可持续发展的重要举措。本文介绍了福州市重力式深水抗风浪网箱发展情况、深远海大型设施化养殖平台发展现状及深远海养殖平台产权登记情况,指出福州市深远海养殖发展的困境,并对福州市深远海养殖的发展提出建议,以期为福州市深远海养殖发展提供参考。

深海采矿转场工况平台——水下系统耦合动力响应特性研究

针对水深6.0 km深海采矿装备,研究其转场工况平台—水下系统耦合动力响应特性。建立深海采矿平台—输浆管—中继站一体化耦合动力模型,其中采用有限元方法离散输浆管,采用势流理论计算平台水动力,基于Kalman滤波对动力定位系统进行参数整定,优化动力定位系统推力。考虑动力定位系统,计算水动力和采矿平台—输浆管—中继站的频域响应和平台—水下系统耦合时域运动响应,计算得到了平台时域运动响应、水下系统动力响应及动力定位系统推力响应。结果表明:建立的一体化耦合动力分析模型是可行的,可以有效预报平台及水下系统响应;转场0°浪向动力定位系统可以有效控制平台运动;中继站运动较小,输浆管轴力较大,建议将输浆管的浮力材料移动到流速较小的水下范围,可降低拖曳力,有利于输浆管的强度性能。

极端海况下新型浮式海上平台生存性试验方法研究

海上平台的安全性越来越受到重视,其安全性在一定程度上取决于安全设计标准和规范。目前针对极端海况下新型浮式海上平台生存性试验方法的有关标准较少。参考国际电工委员技术委员会颁布的IEC TS 62600-103中针对波浪能转换装置在极端海况下的生存性试验标准,在其可操作性和环境条件选取等方面做改进,提出针对新型浮式海上平台的生存性试验方法:选取100年一遇的波浪条件作为基准条件,并以基准波浪条件为中心值,分别选取两组波浪朝向不同、谱形不同、能量不同的对照海况条件,最终形成9组独立的环境条件,用于测试平台针对某一确定波浪海况下的最大响应;确定该波浪条件后,选取100年一遇的风、流条件,进行3组补充测试,分别为风、海流与波浪共向;风与波浪共向且与海流不共向;风、海流、波浪均不共向。并以布放于国家海洋综合试验场威海场区的“国海试Ⅰ”海上试验平台为例,采用数值模拟的方法,研究其在极端海况下的生存性。研究过程验证该生存性试验方法的可行性,提出的试验方法也可为将来相关标准的制定提供参考。

风浪流耦合作用下锚泊式海上试验平台的水动力特性试验

为了研究国家海洋试验场的“国海试1”平台与锚泊优化方案是否满足设计要求,采用物理模型试验方法,制作1∶30试验平台模型,在国家海洋技术中心海洋动力环境实验室开展百余组不同波高、波周期、波向的不规则波、定常风和等效均匀流联合作用下,两点式躺地链系泊状态下的模型运动响应研究。对比分析试验结果与对应试验平台的设计指标,结果表明:同样海况下,风浪与潮流同向时,试验平台的运动响应更剧烈;流速1.14 m/s、4级海况时,试验平台最大横摇角为10.41°,“国海试1”平台无法开展正常的吊装工作;流速1.14m/s、6级海况时,试验平台最大横摇角为15.07°,“国海试1”平台搭载的试验测试设备无法正常工作;流速1.14 m/s、8级海况时,试验平台最大横摇角为20.21°,平台存在安全隐患,应采取避险措施;“国海试1”满足抗7级风浪的设计要求。该研究成果验证了改进后的国家海洋综合试验场“国海试1”平台满足抗7级海况的设计要求。因此,建议“国海试1”平台在6级海况下应停止试验作业,8级海况下应采取必要的避险措施。该研究为同类新型海洋平台水动力研究提供了参考。

我国海铁联运信息平台构建模式

我国海铁联运信息平台经过多年的发展,各联运市场主体已实现了部分数据与信息交换和业务协同,但各类海铁联运业务平台信息未充分整合且标准不一,仍未能向托运人提供“一站式”的运输服务,也未能向多式联运经营人提供足够海铁联运公共信息。针对我国现有海铁联运信息平台以及多式联运经营人发展现状与问题进行分析,提出构建以联盟链技术为核心的区块链海铁联运信息共享平台。在阐述区块链技术基本特征的基础上,从平台构建主体和服务对象、公共信息管理、平台应用层等方面对平台建设进行探讨,并根据海铁联运运输特点探究区块链技术中信息调用机制、共识机制、智能合约在海铁联运业务的应用,为我国海铁联运信息平台升级转型提供研究支撑。

深海探测与驻留装备发展研究

深海探测与驻留装备是发展海洋科学的重要基础。近年来,我国自主研发的相关装备进展良好,但在国产化过程中仍面临一些“卡脖子”技术问题,亟需攻克相应装备的技术短板,推动我国“透明海洋”能力建设。本文在分析深海探测与驻留装备发展需求的基础上,围绕深海通用感知探测设备、深海运载探测通用平台、深水多功能作业平台、深海通导定位装备、深海通用作业工具、深海有人与无人设备的智能控制系统等6个重点领域,系统梳理国内外相关装备的发展现状,深入辨析我国深海探测与驻留装备发展面临的问题。本文论证提出了我国深海探测与驻留装备的9个重点发展方向,涵盖探测装备能源补给、装备系统设计及优化、高功率密度动力、原位实验研究与开发、载人装备宜居与应急救援、水下动态网络定位、水下声光多模混合通信网络、作业人机混合决策与协同控制、人机交互效能评估及优化等关键技术。研究建议,坚持科学发展、加快启动重点海域建设,坚持统筹集约、高效推进共建共用共享,坚持创新驱动、持续发展新技术新装备,以推动我国深海探测与驻留装备的高质量发展。

能耗剖析与绿色创新:深海平台能源效率优化

文章旨在对某深海平台的能耗进行剖析,并探索绿色创新策略以优化其能源效率。换热器作为一种关键设备,在深海环境中承担着重要的任务。为了提高其能源效率,文章对某深海平台中以换热器设备为主的系统能耗进行深入剖析。通过分析能耗数据,以提前发现潜在的能耗瓶颈和不高效的能源利用问题。基于能耗分析的结果,提出一系列绿色创新策略,旨在优化某深海气田换热器的能源效率。通过实施这些策略,期望能够显著降低某深海气田换热器的能耗,提高能源利用效率,并减少对环境的不良影响。文章对某深海气田的能源管理和绿色创新具有重要意义,通过深入剖析能耗,提出节能措施并加以实施,可以实现某深海气田设备的可持续发展和能源效率的显著提升。

温度载荷条件下海上发射平台导流槽结构强度分析

为保证海上发射平台导流槽结构安全,明确海上发射过程中火箭燃气流对导流槽结构的影响,针对半潜式发射平台双侧楔型导流槽结构强度进行研究,提出一种基于CFD模型计算的燃气流载荷转换为结构有限元模型载荷的方法,并利用直接计算法及显式动力学求解方法,对导流槽区域进行静态与动态结构强度分析,参照CCS以及DNV相应规范进行校核。计算结果表明,一体化式导流槽最大应力位置在导流槽支撑结构两侧,应力值为304MPa,最大塑性应变位置在导流面下方支撑结构的圆形开孔处,应变值为1.61×10^(-3)。可拆解式导流槽最大应力位置出现在导流面与两侧结构连接处,应力值为321MPa,最大塑性应变位置在导流面下方支撑结构的圆形开孔处,应变值为1.76×10^(-3),均满足规范要求。

中国海洋平台结构抗冰设计关键问题及研究建议

渤海海域是中国重要的油气产区,但该海域冬季会出现结冰区,因此该区域海洋平台结构的抗冰设计对保障油气增储上产十分重要。渤海海域平台抗冰设计经历了起步、探索、对外合作和独立自主4个发展阶段。本文系统总结了中国渤海地区海洋平台结构抗冰设计面临的关键问题,并给出了相关研究建议。在海冰设计条件方面,受全球气候变化影响,中国海冰冰情整体变弱,现有的海冰区域划分不够精细,部分冰区参数与实际冰情差异较大,且重叠冰设计参数忽视了不同冰区的差异问题,建议基于最新的卫星遥感、业务化预报和实测数据,开展高精细化程度的海冰区域划分研究,并探究工程设计中重叠冰厚度以及强度的合理取值;在结构静态冰载荷计算方法方面,现有计算方法不能适用大径厚比条件,建议基于现场冰力实测和冰水池模型试验,构建新的冰力计算公式,并深入探究多腿结构的遮蔽系数与非同时破坏系数;在动态抗冰设计方法方面,目前尚缺乏明确的可执行规定,尚未建立统一的动冰力模型和疲劳分析算法,建议构建合理的海冰参数概率分布模型,制定平台冰激振动及疲劳设计的设计和评价方法。相关研究成果为中国渤海地区平台结构抗冰设计的优化及下一步研究提供了参考。

复杂及特异性海洋油气生产设施用海范围界定探讨

随着海上油气开采规模的不断扩大,我国海上油气开发的海域使用需求日益强烈。通过收集梳理某海域149个海洋油气生产设施的结构形式、甲板布置等资料,结合近年来的权属核查、勘测数据,在现行《海籍调查规范》《宗海图编绘技术规范》《海域使用论证技术导则》的基础上,从海域管理的角度,重点对《海籍调查规范》未明确或未包含的海上设施用海范围界定方法进行探索,提出主轴法、用海范围规则化等用海界定的新方法,在此基础上完善各类设施用海界定方法。研究提出的界定方法可有效解决现阶段部分海洋油气生产设施用海界定无依据、界定成果与管理部门权属数据管理方式衔接性差,以及界定成果多样化等问题,为我国海洋油气生产设施海域使用的规范化管理及相关技术规范的修订提供参考。

深海油气生产半潜平台新能源供电应用探索

长期以来海上油气田平台的电能均为配置的发电机供给,随着国家碳达峰、碳中和目标要求以及技术的进步,运用其他绿色能源方式替代发电机的电能供给迫切需要且越发可行。海上有着天然的新能源优势,如风能、太阳能、潮汐能等,本文通过介绍深海油气生产半潜平台电力系统、新能源的供电类型,分析适用性及可行性,探索深海油气生产半潜平台新能源供电应用的可能性。

海洋牧场数据分析平台设计与实现

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