尼日尔三角洲深水勘探研究面临的挑战及其对策

面对深水勘探开发钻井和工程难度大、经济投资成本高的特点,针对深水区复杂油气藏,本文首先在深水研究区从深水重力构造形成机制和深水沉积储层研究入手,创新了深水研究区成藏规律认识。在深水重力构造研究方面,发现其由陆向海的演化模式,按演化和特征分成3种类型,建立深水沉积和重力控制下的构造模式;在深水沉积研究方面,以刻画深水沉积特征为基础,分析了海平面升降影响和重力流密度对深水沉积的控制作用,建立了两种深水沉积模式;然后通过研究重力构造、深水沉积与油气成藏三者的关系,确立了重力构造对深水油气成藏的主控作用,以及深水沉积储层与油气富集规律的关系,建立了深水油气成藏模式。在此基础上,提出了以断层为线索,落实构造,追踪油气,以沉积为单元,计算储量和资源量,进行深水高效勘探评价的新方法。并将上述思路应用到深水复杂油气藏勘探研究中,取得了较好的实际效果。     

深部找矿和深部探测中钻探技术的挑战与对策

近10年来,随着钻探工作量大幅度增加,施工的深孔、特深孔数量急剧增长;作为地壳探测工程前期准备的深部探测技术与实验研究专项即将全面完成,万米级科学钻探工程将提上议事日程;这对钻探技术和装备提出了前所未有的挑战。就钻探技术的新进展,深孔、特深孔钻探存在的问题及解决对策进行了初步探讨。     

尼日尔三角洲的重力滑动构造

位于南大西洋东岸被动大陆边缘之上的尼日尔三角洲发育一大型重力滑动构造。自非洲大陆向南大西洋方向,该重力滑动构造可以划分出前缘挤压构造变形区和后缘拉张构造变形区。前缘挤压构造变形,形成褶皱冲断带;后缘拉张构造变形,形成堑垒构造;两者之间的过渡带发育滑脱褶皱。三角洲沉积的时代为始新世—第四纪,地层剖面自下而上依次是海相页岩（Akata组）、近海三角洲相砂岩—页岩互层（Agbada组）和陆相冲积砂岩（Benin组）。3个岩石地层单元都是穿时的,向大洋方向变新。重力滑动构造的主滑脱面位于Akata海相页岩中。根据生长地层、不整合以及卷入变形的地层时代,重力滑动构造起始于约12 Ma,伴生有广泛发育的泥构造。重力滑动构造的形成可能与新生代喀麦隆火山带（Cameroon volcanic line）的火山活动有一定的关系。     

尼日尔河三角洲地下土层工程地质特性初步研究

研究尼日尔河三角洲区域地质调查报告中的钻孔记录及该区勘探工作的实际情况，目的是确定尼日尔河三角洲地区地下土层的工程地质特性及地下土层间的互相联系．按基础工程目的将尼日尔河三角洲划分为3个不同地带，每个带的土层结构和工程地质特性差异较大．①地下土层为砂或粘土的干燥、广阔平原；②地下土层为粘土-砂层双层结构的淡水／咸水沼泽区；③层序为砂-粘土-砂三层结构的海滩／滨海垄区．②和③区中较适宜的地基土相对要少些，此外，象高压缩性混合体的有机质粘土和泥炭质粘上形成普遍不稳定的透镜体，使得土层在横向近距离中的变化应引起高度重视．在5-30m分布有分选性良好的细—中砂层，通常具有很高的承载力，但在沼泽及滨海区，因粘土的介入而有所不同．     

被动陆缘深水重力流沉积单元及沉积体系

被动陆缘深水沉积盆地是深水油气勘探和沉积学研究的热点领域。本文基于尼日尔三角洲西部深水区与珠江口盆地白云深水区的高分辨率三维地震资料开展深水重力流沉积单元和沉积体系研究。主要取得3个方面的认识:①尽管两个地区所发育的重力流沉积体系差异较大,但基本沉积单元是相同的,均由块体搬运沉积体系、深水水道和朵体组成。②尽管不同被动陆缘深水沉积盆地所发育的深水重力流沉积单元基本相同,但由于重力流供给、海底地形、陆坡均衡面以及可容空间和沉积过程等因素的差异,深水重力流沉积体系以及沉积体系叠置样式存在较大的差异。③进行深水沉积单元的识别和表征研究的同时,应加强深水沉积体系控制因素研究,而不能简单地套用某种深水沉积模式。     

南岭区域成矿与深部探测的研究进展及其对西藏钨锡找矿的指示

本文通过对桂西北矿集区、湘南矿集区和赣南粤北矿集区的地质学、地球化学、矿床学等方面的研究,扼要对比了南岭西段、中段和东段的地壳演化历史和区域成矿特点,发现在矿集区尺度上,南岭成矿带西段表现为燕山晚期的爆发式成矿作用;南岭成矿带中段表现为伴随多期岩浆活动而发生多期次成矿,形成多金属矿床;东段虽然也发生多期次的岩浆活动,但成矿作用以燕山期早期第一阶段为高峰;南岭西段也具有发现东段式钨矿的潜力.在不同矿集区深部找矿方向上,南岭西段的少花岗岩地区应重点探测与深部隐伏花岗岩体有关的成矿作用,高温高压成矿实验也表明溶洞式矿体也应列为找矿重点;南岭中段应根据不同的成矿环境探测深部矿体,如黄沙坪矿床深部存在“柿竹园式”矿床;南岭东段,应该在“五层楼”下部寻找“地下室”矿体.在物质来源方面,在湘南骑田岭矿集区的探测技术试验结果表明,骑田岭岩体深部存在地幔物质上涌的通道,岩体中心相的细粒黑云母花岗岩较外围的粗粒黑云母花岗岩混入了较多的幔源物质,白蜡水矿区的富锡流纹质次火山岩脉,也暗示深部存在一期更晚的、含幔源物质更多的岩浆活动,与锡矿成矿物质多来源于地幔的认识一致.根据以上认识,并综合对比南岭与西藏成矿的异同,本文认为在西藏地区,宜在低剥蚀地区的中低温热液矿床的深部探测钨锡矿床,在发育老地层的高剥蚀地区寻找中高温热液型钨锡矿床.     

尼日尔三角洲的沉积-构造特征

尼日尔三角洲位于非洲大陆西海岸的几内亚湾,由尼日尔河注入大西洋形成的,是世界上最大的三角洲之一。它发育于冈瓦纳大陆裂解形成的中、西非裂谷系和大西洋被动大陆边缘交汇部位,主体位于大西洋洋壳之上,部分位于非洲前寒武纪结晶基底之上。中、西非中生代裂谷系通过控制贝努埃-尼日尔河系的发育,间接控制三角洲的形成演化。尼日尔三角洲是一个进积型三角洲,具有典型的进积三角洲沉积序列,自下而上依次是海相页岩(Akata组)、近海三角洲相砂岩-页岩互层(Agbada组)和陆相冲积砂岩(Benin组)。三个岩石地层单位均规律性穿时,向洋方向变新。尼日尔三角洲层序中发育一大型重力滑动构造。该重力滑动构造的主滑脱面位于Akata海相页岩中,可以划分出前缘挤压构造变形区和后缘拉张伸展构造变形区。挤压构造变形区发育褶皱冲断带,伸展构造变形区发育堑垒构造,两者之间的过渡带发育滑脱褶皱。尼日尔三角洲的重力构造伴生有广泛发育的泥构造。重力动构造的形成可能与新生代喀麦隆火山带(Cameroon volcanic line)有一定的关系。     

Lithofacies relations in the Late Quaternary Niger Delta complex

A study of cores from thirty-three coreholes drilled in various parts of the Niger delta has shown tidal channel sand to be the dominant lithofacies type in the uppermost 30 m of the deltaic complex. Below 30 m fluviatile sand becomes predominant. Coastal barrier sand is present in the uppermost 5 m of the present coastal belt, but chances for preservation of this lithofacies appear to be small. The Post-Glacial deltaic sediments can be divided into three units.

• 1 Alluvial valley-fill sands and conglomerates deposited during the strong Post-Glacial sea level rise.
• 2 An onlapping complex of lower coastal plain deposits which contains a lower member of fine grained lagoonal and mangrove swamp deposits and an upper member of tidal channel and coastal barrier sands. This complex is thought to have been deposited during the strong Post-Glacial rise in sea level and is locally as much as 25 m thick.
• 3 An offlapping complex of fluviomarine and coastal deposits which contains a lower member of marine clay and silt and an upper member of tidal channel and coastal barrier sand. The presence of this late Holocene complex indicates that deltaic progradation was resumed as soon as the rapid rise in sea level slowed down. The offlapping complex is locally as much as 35 m thick.

     

地勘单位改革所面临的困境及对宁夏煤田地质局的影响

宁夏煤田地质局作为宁夏回族自治区唯一专业从事煤田地质勘查的单位,由于历史背景、区域特点的差异．与全国各地质勘查单位相比,在改革进程中所面临的问题,除人才缺乏、资金紧张、资产有限等共性问题外．还有许多个体差异,这些因素严重制约着宁夏煤田局做大做强及可持续发展。参照内蒙、广东和陕西三省地勘单位的改革经验,认为地勘单位企业化改革不能等同于地勘行业的改革．地勘单位企业化改革的成败与事企及产权明晰程度有关,长期积累的顽症决定了事转企的改革具有阶段性、差异性。宁夏煤田地质局的事转企改革与可持续发展应在宽松的矿政环境及优惠政策下推进,并创造条件向产业链中的高利润产业拓展。     

Case histories of sand search in the Niger Delta

This paper discusses the imperatives of sand search and describes two case histories of sand search in the Niger Delta. These case histories highlight the project cycle of sand search operations and circumstances in which environmental peculiarities can influence procedures and strategies. Field and laboratory procedures emphasise the applications of particle-size distribution and compaction tests to field construction control. The need to integrate mitigative measures of potential impacts into the planning and execution of projects has been emphasised. Some environmental consequences of sand dredging have also been highlighted.     

尼日尔三角洲深水区层序地层及地震相研究

中新世至上新世,研究区发育深海平原和陆坡坡脚沉积。缺少反映海平面变化的上超特征和削截现象,很难利用地震反射终止类型（上超、顶超、削截）进行层序界面识别。文中利用深水区沉积旋回的地震相特征差异进行层序界面识别,并建立了研究区层序演化模式:低位体系域发育重力流沉积（块状搬运复合体、浊积扇）———海侵高位体系域深海泥质发育。以层序为格架进行地震相和沉积相在时间和空间分布特征分析。研究区识别出两类叠加地 震相样式:杂乱反射块状搬运复合体———丘形水道—堤岸复合体（浊积扇）———平行反射深海泥质沉积;丘形水道—堤岸复合体（浊积扇）———平行反射深海泥质沉积。     

尼日尔三角洲盆地深水沉积体系特征

尼日尔三角洲盆地深水沉积研究是目前世界油气勘探的热点问题之一.通过对三维地震资料、岩心及测井曲线分析,揭示了尼日尔三角洲盆地南部地区新近系深水沉积体系特征.基于不同属性的层序界面识别,研究区划分出SQ1-SQ6共6个三级层序,并建立层序地层格架,进而总结出研究区深水沉积模式.研究区除堆积正常半深海-深海泥岩外,还广泛发育海底扇沉积,海底扇由浊积水道和海底扇朵体组成,其中水道分支少、弯度大,外部形态类似曲流河;朵体平面上成朵叶状分布,可以划分为末端朵体和决口扇朵体.研究区新近系地层自下向上由老到新,相对海平面先下降再上升,SQ1-SQ4层序以海底扇朵体沉积为主,SQ5-SQ6层序以浊积水道沉积为主.      

Polycyclic aromatic hydrocarbons in Niger Delta soil: contamination sources and profiles

The distribution and sources of PAHs in soil as well as PAHs profiles have been investigated in areas with anthropogenic pollution in the Niger Delta (Nigeria) such as Warri and Ughelli. PAHs were identified in 21 soil samples (0–10cm upper layer) collected in May, 2003. The typical total PAHs level in Niger Delta soil ranged from 182 ± 112 - to - 433 ±256 íg/kg dw. PAH concentrations in soil samples from Warri Refinery, Tanker Loading point and Ugboko via Rapele oil field were quite high ( the mean ÓPAH concentrations were 433, 402 and 384 íg/kg dry weight respectively). The dominant PAHs in soil samples were pyrene, naphthalene and benzo[k]fluoranthene. The soil total PAHs (PAH_tot.) concentration, normalized to organic carbon content (OC), ranged from 11.4 to 47.2 mg PAH_tot. /kg OC; and showed that organic matter of the soil samples from Quality Control Centre, Ugelli West is highly contaminated with PAHs and had a value of 47.2 ± 31.2 mg PAH_tot./kg OC. Two and three ring aromatic hydrocarbons predominated in soil samples from Ughelli West, Tanker Loading point and Delta Steel Company, which is indicative of petrogenic origin.     

尼日尔三角洲盆地深水区逆冲构造演化特征

关于尼日尔三角洲盆地陆坡深水区的逆冲构造,其逆冲背景下的构造演化阶段及古地貌变迁特征,是一个需要深入研究的问题。以尼日尔三角洲盆地某深水研究区为例,基于三维地震资料解释,识别了3个关键界面和4种构造样式,将新生界划分为3个超层序,进一步分析了SSQ_1超层序内部的泥岩滑脱面;厘定了中新统逆冲构造的演化阶段,并分析了不同阶段内的地貌特征。形成于构造活动期的超层序(SSQ_3)可进一步划分为3个三级层序,自下而上依次由逆冲断层、泥底辟和披覆沉积所主控,对应3个不同的构造演化阶段:①逆冲断层主控阶段。在重力滑脱作用下,逆冲断层沿不同深度滑脱面发育,所产生的位移差导致构造变换带内地层受到剪切应力而发育撕裂断层,其走向与逆冲断层近垂直;剪切破裂面的存在使地层抗应力强度大幅降低,在地层超压作用下,构造变换带内沿撕裂断层发育泥底辟褶皱;顺陆坡倾向搬运的重力流沉积物受到逆冲相关褶皱阻挡而发生沉积,导致重力流岩性圈闭集中分布于逆冲断层上盘的地貌低部位。②泥底辟主控阶段。在差异负荷作用下,塑性超压泥岩向逆冲相关褶皱与撕裂断层相关褶皱核部集中,形成大型滑脱褶皱;泥岩的塑性变形主要发生在由不同深度滑脱面所限定的地层单元内;滑脱褶皱的存在使其两侧形成了沿陆坡倾向展布的地貌低部位,并成为重力流储层发育的有利场所。③构造平静阶段。构造活动明显减弱,在填平补齐作用下地貌逐渐趋于平缓。     

Active Soils of the Niger Delta in Road Pavement Design and Construction

Active soils existing to irreplaceable extents (both laterally and vertically) within the freshwater zone of the Niger delta are known and have been shown to be highly undesirable in their natural forms for road construction. This is because they swell extensively in the rainy season and shrink proportionately in the dry months together with any structure including road pavement constructed with or placed on them. In this paper, four samples of these soils collected from across the Niger delta were subjected to chemical stabilization with slaked-lime and calcium chloride (CaCl₂) to reduce swelling potential while resulting mixtures (corresponding to tolerable swelling limits) were stabilized with Portland cement to improve strength. First, swell indicator (i.e. 24-h free swell index) was found to diminish with increasing stabilizer content while for combined plot (independent of location/percentage fines), about 10.7% and 6% slaked-lime and CaCl₂ were found to be required to achieve the minimum (2.5% free swell) tolerable, normal or non-swell soil condition. Under this condition and for individual soil materials, addition of cement was found to enhance continual increase in MDD, soaked-CBR and durability index such that the soil becomes better compactible, stronger and more durable with increasing cement content. About 2.6% and 14.6% cement contents were found needed to respectively produce sub-base and base-course materials in roadworks with the latter much more durable than the former. The graphs so obtain could also constitute a complete graphical model for preparing deltaic active soils for use as road pavement materials.     

Groundwater quality assessment in parts of Eastern Niger Delta, Nigeria

Hydrogeochemical analyses were carried out on groundwater samples collected from 20 producing wells in different parts of the Eastern Niger Delta. Results show that the concentrations of the major cations (Na⁺, K⁺, Ca²⁺, Mg²⁺) and anions (Cl^–, SO ₄ ^2– , HCO ₃ ^– ) are below the World Health Organization (WHO) standards set for domestic purposes. The occurrence of slightly saline water in certain areas is attributed to local hydrogeological processes occurring in the area. On the basis of the analytical results, two hydrogeochemical facies are delineated. These are calcium-magnesium-chloride-sulfate-bicarbonate (Ca-Mg-Cl-SO₄-HCO₃) and calcium-sodium-chloride-sulfatebicarbonate (Ca-Na-Cl-SO₄-HCO₃) to the west and east of the study area, respectively.     

Fold crest degradation and slump deposition in the deepwater Niger Delta,Nigeria

This study uses 3D seismic reflection dataset to investigate the time-integrated growth and degradation of fault-propagation folds and associated slump deposits in the deepwater Niger Delta. The results of the analysis showed that slump deposits are sourced almost entirely from the degradation of growing fold crests—resulting in the development of seaward-facing scarps on the forelimbs of these folds. The scarps develop parallel to fold axes and have dips that range between 4° SW and 20° SW. The constant presence of fan-shaped slump deposits downdip of these scarps suggests a direct relationship to fold crest degradation. Moreover, the spatio-temporal distribution of the slumps also shows a direct relationship with the heights of seabed scarps along the strike of growing folds. Slumps have short run-out distances (generally less than 5 km); however, they also travel long distances downslope (up to 10 km) across growing structures by exploiting relay areas between growing scarps.     

尼日尔三角洲坡脚逆冲带沉积样式及构造控制

研究尼日尔三角洲深水坡脚逆冲带沉积样式、构造对沉积的控制可以揭示深水沉积分布与演化特征.运用生长地层翼旋转机理和地震相分析技术对研究区的沉积类型、构造与沉积关系进行了分析.认为在深水陆坡重力滑动作用所形成的微盆地内, 层序边界表现为微盆地边缘上超不整合面或重力流对下伏地层的侵蚀不整合; 逆冲构造隆升速率与沉积速率共同控制了重力流可容空间和沉积充填样式; 沉积垂向演化以块状搬运复合体-浊积扇-深海披覆泥或浊积扇-深海披覆泥为特征.在充分考虑构造隆升和沉积速率影响因素的基础上, 建立了单一微盆地和多个微盆地的沉积演化模式.      

Shallow resistivity measurement for cathodic protection of pipelines in the Niger Delta

The variation in the geo-electric resistivity of the superficial soils across the Niger Delta was investigated by running profiles spanning over 350 km and covering all the geomorphic zones of the Niger Delta, using a Schlumberger electrode configuration. The results indicate characteristic resistivity ranges. The spatial variation in resistivity was explained by differences in topographic elevation, depth to water table, soil type, and water quality. Based on the soil resistivities in the various geomorphic zones, the corrosivity of the soils were determined and methods of cathodic protection prescribed. A north–south traverse will generally experience a decreasing soil resistivity that is truncated at the beach ridges.     

An ancient submarine canyon in the Oligocene-Miocene of the western Niger Delta

ABSTRACT
An anomalous sequence of thick fossiliferous marine shale of late Oligocene-early Miocene age, here termed the Opuama Shale Member, occurs within the paralic Agbada Formation in the subsurface of the western Niger Delta. The Opuama Shale fills a deep palaeochannel which was cut into Eocene-early Oligocene paralic beds. Planktonic and benthic foraminifera suggest that deposition in the channel began in the late Oligocene-early Miocene at outer shelf-slope depths, and that by the late early Miocene the channel had filled to shallow neritic depths. The channel, which is believed to be of submarine origin, is termed the Opuama canyon. The Opuama canyon originated during the pronounced early-Middle Oligocene drop in sea-level, and was cut by turbidity currents. It was filled, during the major late Oligocene-early Miocene rise of sea-level.
The location of the Opuama canyon in the western re-entrant of the Niger Delta supports Burke's (1972) conclusion that the western and eastern (where ancient submarine canyon fills are known) re-entrants of the delta are potential sites for ancient submarine canyons. Burke based his conclusion on the observation that the eastern and western re-entrants of the modern delta are areas where opposing longshore drifts converge and generate turbidity currents which cut submarine canyons.