Benin and Western Nigeria Offshore Basins: A Stratigraphic Nomenclature Comparison

The Benin and Western Nigeria Offshore Basins, which are parts of an extensive basin called the Dahomey (Benin) Embayment, were formed during the Early Cretaceous under similar tectonic conditions and continental sedimentary environments. Based mainly on available lithological, biostratigraphic and paleoenvironmental data, this paper summarizes the stratigraphic succession of theses basins and attempts a comparison of these stratigraphic nomenclatures. The bulk of data shows that sedimentation begins with terrestrial at the base, passes through shallow marine, deep marine (with restrictive bottom circulation) and ends with open deep marine conditions. The stratigraphy of the Offshore Benin Basin was established later and considering lithological and paleontological similarities with formations of various southern Nigeria basins, the stratigraphic chart adopted for this basin was a mixed variant of various Southern Nigerian basins nomenclatures. For the first time, a correlation of stratigraphic charts of each basins and a schematic cross section showing their lithostratigraphic units, especially the Cretaceous-Paleocene interval which is petroliferous, are proposed. The study shows that the nomenclature adopted in Benin Republic must be revised by using type section/locality names for some particular Formations and widely accepted Formations names of Nigeria for the others. This will permit to avoid confusions as it is presently the case for the name “Afowo Formation” representing a Cretaceous sequence in Nigeria and which is use in Benin Republic to distinguish some sediments of Miocene age. Moreover, a High Resolution Biostratigraphy summary (including micropaleontology, nannopaleontology and palynology distributions) relating to each offshore basin is needed for sequences correlations and entire harmonization of the stratigraphic nomenclature of these offshore basins.

Cenozoic giant coal-bearing basin belt discovered in China's sea and its adjacent areas

Sea area is an important area of oil and gas exploration in China.It has been found that China's sea area mainly consists of coal type oil and gas,and the exploration of coal-bearing series source rocks has become an important part of oil and gas exploration there.Through years of comprehensive geological research in China's sea area,it has been revealed that it has undergone multiple occurrences of tectonic opening and closing movements in varying degrees in the Paleogene,forming 26 Cenozoic sedimentary basins of various types,such as active continental margin,passive continental margin,transitional continental margin and drift rift basins.In the present study,it is observed for the first time that coal type source rocks are mainly developed in 14 continental margin basins in China's sea area,revealing that a very large C-shaped coal-bearing basin group developed there in the Cenozoic.Next,based on the coupling analysis of paleoclimate,paleobotany,paleogeography and paleostructure,it is observed that there are five coal-forming periods in China's sea area,namely the Paleocene,Eocene,early Oligocene,late Oligocene and Miocene-Pliocene,and the coal-forming age is gradually new from north to south.It is also found that the coal seams in the sea area are mainly developed in three coal-forming environments in Cenozoic,namely delta,fan delta and tidal flat-lagoon.The coal seams developed in different environments are characterized by thin thickness,many layers and poor stability.However,the coal-bearing series source rocks in China's sea area have a wide distribution range,very high thickness and large amount,thus forming a material basis for the formation of rich coal type oil and gas.

Geochemistry of Cretaceous Sea Rocks from the LEO-3X Well in the Eastern Abidjan Margin, Côte d’Ivoire Offshore Basin

In this study, we apply geochemical and statistical analyses to evaluate the source rocks and kerogen type of Cretaceous sediments from the Cote d’Ivoire sedimentary basin. The geochemical analysis includes pyrolysis data such as total organic carbon (TOC%), generation source potential (S2) and hydrogen index (HI). The results of the cluster analysis separated the source rocks in the study area into two main groups. 1) Source rocks characterized by HI > 300 (mg/g), TOC from 1.76% to 3.19% by weight, and S2 from 6.55 to 14.46 (mg/g), indicating good to excellent source rocks with type II kerogen and are capable of generating oil. 2) Source rocks characterized by HI between 200 and 300 (mg/g), TOC from 1.6 to 2.02 wt%, and S2 from 3.45 to 5.36 (mg/g) indicating medium to good source rocks with type II-III kerogen and capable of generating a mixture of oil and gas.

Chemostratigraphic Characterization Tests on Sedimentary Formations in the Côte D’Ivoire Offshore Basin: Case of A-X and B-X Wells

The tests performed with two hundred and thirty-nine (239) samples from the A-X and B-X drillings help to know their sedimentological and chemostratigraphic characters. In sedimentological term formations are composed of sand, sandstone, limestone, siltstone and argillite that alternate along the drill. In chemostratigraphic term two megasequences (MS1 and MS2) have been identified. A correlation of chemostratigraphic data completed by the lithology results allowed a subdivision of oil wells that shows two main types of deposits environments. First, a proximal marine environment to continental and to Albian marked by a detrital flow deducted from the concentrations evolution of indicator elements of terrigenous material that are K, Mg, and Rb. On the other hand, a deep to shallow marine environment of Cenomanian to Paleocene marked by the presence of predominantly clay sediments and abundant glauconite in the lower Senonian. Nevertheless, there is a transition or intermediate environment that is characterized by the presence of glauconite and detrital flows.

基于重磁数据研究江苏岸外滨海断裂带及邻区构造特征

江苏岸外滨海断裂带是南黄海西部一条重要的活动断裂,孕育了多次M≥5.0的破坏性地震。该断裂带所在海域特殊的自然地理条件限制了海洋地质调查的开展,导致目前对其展布特征、断面结构、活动强度和力学性质等仍存在争议。文章基于重磁异常的定性分析和定量计算并结合前人研究成果,对滨海断裂带及邻区的构造特征进行研究,追踪了滨海断裂带可能的展布特征,并探讨了不同分段构造属性和活动性。结果表明,滨海断裂带在江苏岸外20~30 km处大致平行于岸线延伸,在废黄河口以北分叉为东、西两支。推测大致以射阳和如东海域为界,将断裂带分为3段。中段构成苏北盆地的东部边界,为长期继承性活动的深大断裂;南段为形成时代较新的平移断裂,构造活动性最强;北段的存在与否和活动性仍有待进一步调查确认。

海上咸水层CO_(2)封存潜力研究进展

气候变化是当今人类面临的重大全球性挑战。中国作为全球第一大碳排放国,在全球气候治理中起着关键作用。继2015年《巴黎协定》之后,2020年中国在第75届联合国大会一般性辩论和气候雄心峰会等重要会议上,首次提出了争取2030年前碳达峰、2060年前碳中和的目标。然而作为第一大能源消费国.

北部湾盆地涠西南凹陷咸水层CO_(2)地质封存储盖优选及潜力评估

CO_(2)地质封存被认为是实现碳中和目标的兜底技术,近海沉积盆地远离人类活动区,在实施CO_(2)地质封存方面相比于陆上沉积盆地更具优势。为查明广东省近海北部湾盆地涠西南凹陷咸水层CO_(2)封存潜力,基于盖层埋深、单层泥岩最大厚度、泥地比、断层密度和储层孔隙度、地层厚度、砂地比、渗透率等8个指标,构建了盆地二级构造单元的储盖评价体系,结合各地层岩心物性资料和三维地质模型,对涠西南凹陷储盖进行优选,并以US-DOE法对有效封存潜力进行了评估。研究结果表明,涠西南凹陷在海底以下800~3000 m内,有2套适宜CO_(2)封存的储盖组合。储盖组合1:新近系角尾组一段浅海相泥岩盖层−角尾组二段、下洋组滨浅海相砂岩储层,有效封存容量为7.49亿t;储盖组合2:古近系涠洲组二段中深湖泥岩盖层−涠洲组三段砂岩储层,有效封存容量为3.74亿t。在涠西南凹陷中优选出2套适宜咸水层封存CO_(2)的储盖组合,有效封存容量为11.23亿t,按照广东省粤西地区CO_(2)年排放量为7000万t进行评估,能够满足该地区超16 a的CO_(2)减排需求。

Formation conditions and accumulation characteristics of Bozhong 19-6 large condensate gas field in offshore Bohai Bay Basin

Based on the study of natural gas resource, low buried hill trap formation mechanism, high quality reservoir control factors and natural gas preservation conditions, the formation conditions and reservoir accumulation characteristics of Bozhong 19-6 large condensate gas field were summarized. Large gas generation potential of multiple sets of thick humic-sapropelic source rocks in high maturity stage in Bozhong depression was the basis of large gas field formation. The multi-stage tectonic evolution since Indosinian period formed large-scale buried hill traps. The Tanlu fault activity formed multi-type reservoirs, and buried hill metamorphic rock of Archean and sand-conglomerate of Kongdian Formation were high-quality reservoirs. Thick overpressure lacustrine mudstone and weak neotectonic movement provided good preservation conditions. Bozhong 19-6 gas reservoir was a condensate gas reservoir with very high condensate oil content, and the gas origin was humic-sapropelic and kerogen-cracking gas, and the gas field had large gas thickness, high gas column characteristics and the accumulation process was first oil and then gas. The buried hill reservoir was a massive reservoir and the Kongdian reservoir was a stratified reservoir. The gas field had multi-channel hydrocarbon intense charge from overpressure source rocks, atmospheric-weak overpressure reservoir favorable for accumulation, thick overpressure mudstone caprock favorable for preservation, and natural gas ultra-late rapid accumulation model.

Exploration prospects of oil and gas in the Northwestern part of the Offshore Indus Basin, Pakistan

Oil and gas resources are short in Pakistan and no commercially viable oil and gas sources have been yet discovered in its offshore areas up to now.In this study,the onshore-offshore stratigraphic correlation and seismic data interpretation were conducted to determine the oil and gas resource potential in the Offshore Indus Basin,Pakistan.Based on the comprehensive analysis of the results and previous data,it is considered that the Cretaceous may widely exist and three sets of source rocks may be developed in the Offshore Indus Basin.The presence of Miocene mudstones has been proven by drilling to be high-quality source rocks,while the Cretaceous and Paleocene–Eocene mudstones are potential source rocks.Tectonic-lithologic traps are developed in the northwestern part of the basin affected by the strike-slip faults along Murray Ridge.Furthermore,the Cretaceous and Paleocene–Eocene source rocks are thick and are slightly affected by volcanic activities.Therefore,it can be inferred that the northwestern part of Offshore Indus Basin enjoys good prospects of oil and gas resources.

Analysis of Key Disciplinary Parameters in Floating Offshore Wind Turbines with An AI-Based SADA Method

Floating offshore wind turbines(FOWTs)are a promising offshore renewable energy harvesting facility but requesting multiple-disciplinary analysis for their dynamic performance predictions.However,engineering-fidelity level tools and the empirical parameters pose challenges due to the strong nonlinear coupling effects of FOWTs.A novel method,named SADA,was proposed by Chen and Hu(2021)for optimizing the design and dynamic performance prediction of FOWTs in combination with AI technology.In the SADA method,the concept of Key Disciplinary Parameters(KDPs)is also proposed,and it is of crucial importance in the SADA method.The purpose of this paper is to make an in-depth investigation of the characters of KDPs and the internal correlations between different KDPs in the dynamic performance prediction of FOWTs.Firstly,a brief description of SADA is given,and the basin experimental data are used to conduct the training process of SADA.Secondly,categories and boundary conditions of KDPs are introduced.Three types of KDPs are given,and different boundary conditions are used to analyze KDPs.The results show that the wind and current in Environmental KDPs are strongly correlated with the percentage difference of dynamic response rather than that by wave parameters.In general,the optimization results of SADA consider the specific basin environment and the coupling results between different KDPs help the designers further understand the factors that have a more significant impact on the FOWTs system in a specific domain.

China's Software Industry Aiming at a Higher Standard

The current status of the China's software industry is introduced, including the great potential opportunities and many problems across the path to success. The main measures are discussed to keep abreast of the time needs and fuse with the whole family of global IT industry.

Tectono-Sedimentary Evolution of the Offshore Hydrocarbon Exploration Block 5, East Africa: Implication for Hydrocarbon Generation and Migration

Sedimentary deposits in Block 5, offshore Tanzania basin have been imaged using two-dimensional (2D) seismic data. The seismic data and well data reveal four tectonic units representing different tectonic events in relation to structural styles, sedimentation and hydrocarbon potential evolved in Block 5. Results show that during Early to Late Jurassic, Block 5 was affected by the break-up of Gondwana and the drifting of Madagascar as evidenced by patterns of sediments and structural features. The chaotic and discontinuous reflectors are characteristics features on the sediments pattern indicating a possible transitional setting following the breakup of Gondwana. From the Late Cretaceous, Block 5 sits in more stable subsiding sag as the consequence of the high thermal subsidence. The period displayed continuous parallel reflectors with few markable faults. This was followed by the late post rift sedimentation that occurred after Middle Eocene Unconformity characterized by high wavy and sub parallel reflectors. The evolution of Block 5 through major tectonic events reveals a more complete petroleum system towards the south. Thus, Block 5 responded in both space and time to a complex interplay between tectonics and sedimentation. This indicates that structural styles and associated features are potential control for hydrocarbon generation and migration.

Exploration Prospect of Offshore Petroleum in China

The anticline is large in size and gentle.an individual structure covers an area up to 100-300.km*.At top of mudcone little tensional faults are often associated.The mudcones themselves are either possible source rock bodies or hydrocarbon-draining.pressure-releasing paths.Natural gas migrated upwards along mudcone diapir zone and faults.and accumulated in the upper structural.traps.The already drilled Dongfang 1-1 and Ledong 15-1 Structures are identified to bre gas-bearing structures.Some structures similar to them.such as Cangjiang 29-1.Ledong 8-3 and Ledong 16-1 Structures.are today's exploration targets.Most of this type of traps contain gas.But three aspects still need to be studied in future:firstly.overpressure and high-temperature result in difficulties of drilling engineering:secondly,reservoirs do not develop very well or are not high-quality:thirdly.there is non-hydrocarbon gas such as CO2 to be.associated with.so the fluid properties are more complicated.

海上新区油气勘探突破典型案例分析及启示

随着陆地勘探程度越来越高,获得大发现的难度越来越大,油气勘探向海域拓展是大势所趋,加快海域新区突破、实现资源有序接替,具有十分重要的战略意义。重点剖析了渤海湾盆地秦皇岛32-6油田、黎凡特盆地塔马尔气田两个海域大发现的勘探历程,梳理每个勘探阶段的指导思想、部署思路及做法,探讨制约突破发现的因素及推动勘探突破的地质认识转变和思想革新。研究显示,盲目跟风追热点、未找到适合的理论指导制约了渤海湾油田发现;客观分析成藏特征,转变思路,以新近系为主要目的层,以生烃凹陷包围的隆起区及其倾没带为主要勘探方向,推动了秦皇岛32-6油田大发现。黎凡特盆地塔马尔气田的发现则归因于储层物源和低成熟生物气的新认识及较高的勘探投入。研究认为,摸清成藏规律是推动大发现的内在动因,尤其是深海前沿领域勘探;关键成藏要素的颠覆性认识是突破关键,保证持续稳定的勘探投入是推动海域新区突破的前提条件。

离岸碳捕集利用与封存技术体系研究

离岸碳捕集、利用与封存(CCUS)技术是沿海国家或地区通过工程方式为实现CO_(2)减排而发展起来的解决方案与技术体系;相对于陆上CCUS技术,具有潜在封存空间广阔、封存安全等诸多优势。离岸CCUS技术指从沿海大型或近海碳排放源捕集CO_(2),加压并运输至离岸封存平台后注入海底地质储层中,实现CO_(2)与大气永久隔离或利用其生产价值产品的过程。本文概要回顾了全球及我国离岸CCUS技术的发展需求与产业现状,分析了发展离岸CCUS的技术性和社会性价值;梳理总结了代表性的离岸CCUS技术发展路线及其态势,如CO_(2)工厂捕集、CO_(2)管道运输、CO_(2)海底咸水层封存与驱油利用、CO_(2)化学利用以及其他技术架构。着眼不同技术创新方向面临的共性问题,提出我国离岸CCUS领域未来发展建议:注重陆海统筹战略规划和布局,培养高水平研究团队,加强各发展阶段的基础研究、核心技术研发、成本控制、规模增扩和政策激励等。

中国海及邻区盆地现今地温场特征及其影响因素

现今地温场是构造活动、岩石圈热状态的综合反应,对研究盆地的区域构造演化、深部岩石圈结构和评估油气潜力具有重要意义。地温梯度和大地热流是表征沉积盆地热状况的两个基本参数。虽然我国大陆地区地热数据较丰富,并已经过四次系统汇编,但中国海及邻区盆地地热数据报道较少,且未经过系统整理。本文基于近年来新增的钻井温度数据,新增计算研究区810个地温梯度数据,并收集了国内外数据库、期刊的地热数据,在此基础上,首次系统整理了中国海及邻区盆地地温梯度数据和大地热流数据,绘制了其等值线图,分析了研究区现今地温场特征并讨论了其影响因素。研究结果表明,中国海及邻区盆地平均地温梯度43.2±25.7℃/km,平均大地热流74.4±26.6 mW/m^(2),多数盆地平均大地热流高于65 mW/m^(2),属于“热盆”;地温场分布总体呈现较为明显的“两带性”,其中近岸带较冷,远岸带较热;研究区现今地温场特征直接或间接地受控于其所处的构造环境,整体上是太平洋板块等多板块作用下岩石圈伸展减薄的结果,局部地区的热异常可能与断裂活动、岩浆活动、泥-热流底辟活动等因素有关。

东非海域大型深水沉积体系及油气成藏特征

基于高品质三维地震和测井、录井等资料,对东非鲁伍马盆地古新统—渐新统深水沉积体系和赞比西坳陷上白垩统深水沉积体系特征进行了分析,并对二者的成藏条件进行了类比研究。研究结果表明:①鲁伍马盆地古新统—渐新统深水沉积体系中发育水道和朵体砂岩等大规模优质储层,等深流的改造作用是优质储层形成的关键因素。②赞比西坳陷上白垩统发育水道、朵体、块体搬运沉积等典型深水沉积,规模巨大的等深流漂积体多为优质储层。③赞比西坳陷主力烃源岩为下白垩统局限海相泥岩,油气生成后运移至邻近的上白垩统深水沉积砂体中,并被高位体系域深海泥岩封盖,深水砂岩上倾尖灭形成了岩性圈闭,具备良好的油气成藏条件,是未来油气勘探的有利区。

水平井地质导向技术在海上油田薄油层开发中的应用

针对海上油田薄油层开发面临的油层厚度薄、局部微构造变化、储层内部夹层发育、油水界面上升等问题,基于地球物理、开发地质、油藏工程、钻井工程、测录井工程等多学科综合运用的优势,总结出一套包括储层精细预测技术、高精度地质建模技术、油藏数值模拟技术和地层边界探测技术在内的多专业一体化海上油田薄油层地质导向技术。该项技术在A油田厚度约2 m薄油层应用过程中,分别从水平井的钻前综合分析、钻中实时调整和钻后地质认识3个阶段展开,最终水平段储层有效钻遇率达100%,投产后生产效果远超设计产能,为该油田薄油层产量最高井,对海上其他油田薄油层开发具有参数借鉴意义。

中国近海新生代盆地构造差异性演化及油气勘探方向

中国近海处于欧亚、印度-澳大利亚及太平洋三大板块的交汇地带,其盆地形成与演化受控于洋、陆板块的相互作用,区域构造背景对盆地形成和演化起到了重要的作用,并由此导致了中国近海盆地显著的分段性和差异性演化特征。渤海海域、北黄海至南黄海盆地属于陆内裂陷型盆地;东海海域为活动大陆边缘弧后裂陷型盆地;珠江口盆地和琼东南盆地为被动大陆边缘型盆地;莺歌海海域为转换大陆边缘型盆地。受此影响,油气分布有明显的分段分区性,渤海—南黄海陆内盆地以成油为主,东海弧后盆地以成气为主,南海北部大陆边缘北部成油、南部成气,莺歌海转换盆地以成气为主。中国近海未来的找油领域主要在渤海、珠江口盆地北部和北部湾盆地;找气领域主要在东海盆地、南海北部深水区和莺歌海盆地6大领域。

世界主要深水含油气盆地储层特征

世界深水盆地油气资源丰富,良好的储层是形成较大油气藏的必要条件。以大量调研资料为基础,对大西洋区域的墨西哥湾、巴西东部边缘、非洲西海岸、挪威中部陆架及新特提斯区域的澳大利亚西北陆架、中国南海、孟加拉湾、地中海(尼罗河三角洲)8个地区的24个深水含油气盆地储层特征进行了综合分析,归纳总结了这些深水含油气盆地中主力储层的形成时代、构造背景、沉积环境等特征,探讨了其分布规律。结果表明,世界深水含油气盆地主力储层集中在白垩纪及古近纪,大西洋区域深水盆地主力储层呈"北早南晚"的特点,新特提斯区域深水盆地呈"古近纪为主"的特点;漂移期储层占绝对优势,大西洋深水盆地群主力储层有"北裂南漂"的特点,新特提斯区域深水盆地主力储层多集中在漂移期;沉积相以深海浊积砂岩和河流—三角洲砂岩为主,大西洋区域深水盆地主力储层呈"北部滨浅海相、南部深海相"的分布格局,而新特提斯区域深水盆地以"河流—三角洲—滨浅海相"为主。