沉积盆地中超压力的形成机理

下列作用可引起超压力:①挤压应力的增大;②孔隙流体或岩石基质体积的改变;③流体的运移或浮力。由于压实作用不均衡,埋藏期间特别是低渗性沉积物迅速沉降期间的负荷能产生相当大的超压力。在构造活动地区,水平应力的改变能迅速产生和耗散大量超压力。与体积变化有关的超压力的形成机理要求必须具备良好的有效的封闭系统。与热液膨胀和粘土脱水有关的流体体积的增加太少,不能产生大的超压,除非有理想的密封体系存在。烃类的形成和裂解为天然气可以产生超压,这主要取决于干酪根的类型、有机质的丰度、温度和岩石的渗透率。然而,由于压力的形成阻碍有机质的进一步变质,所以在封闭系统中这些作用可能受限。由烃类的形成和裂解产生超压的可能性在目前还未被证实。水压头造成的流体运动在浅埋藏的“铅垂”盆地内可能会形成超压。经计算表明,烃的浮力和渗透性所产生的局部超压力很小。在不可压缩的流体中,气体的向上运移也能产生一定的超压力,但需要进一步研究。在许多沉积盆地中与应力相关的机理是产生超压力的最主要原因。     

Pericontinental petroliferous basins of the South Atlantic Ocean

Sedimentary basins located at Atlantic margins of South America and Africa (Brazil, Congo, and Angola) are composed of thick Cretaceous-Pleistocene rocks (7–9 km). The principal oil-bearing complexes of both regions are dominated by terrigenous rocks. Their accumulation took place at the rifting stage, ended with precipitation of evaporites in the Aptian at the oceanic stage of evolution. Starting with Coniacian and Campanian, the accumulation of terrigenous clastic formations in the Santos and Campos basins was governed by main phases of orogenesis in the Peruvian Andes. In the Angola and Lower Congo basins, the sedimentation was governed by movements related to the development of the East African Rift System. The formation of carbonate and carbonate-clayey sediments prevailed here at early (Albian-Late Eocene) stages of the South Atlantic opening.     

中国含油气盆地沉积研究主要科学问题与发展分析

沉积相研究发展与人类的生存和矿产资源勘探开发密切相关.该文在简单回顾了近200年的沉积学发展历史的基础上,分析了国际和中国沉积学关注的学科热点问题.国际沉积学会重点关注的问题主要包括国际大洋钻探计划、深-时气候变化与全球海平面变化、源-汇系统、碳酸盐岩沉积环境、混合沉积、微生物岩、陆架边缘三角洲、重力流、细粒沉积、构造...     

Structure and geological history of sedimentary petroliferous basins in the North Atlantic

Pericontinental sedimentary basins in the northern Atlantic Ocean contain the largest reserves of oil and gas. In the Paleozoic-initial Paleogene period, they were developing as rift grabens subjected to repeated tectonic dislocations. Spreading of the oceanic bottom that started in this region in the Paleocene-Eocene was accompanied by rapid subsidence with accumulation of volcanogenic and turbiditic sediments. All these processes resulted in the formation of a thick sedimentary cover with both oil source and reservoir rocks at its different levels. The region under consideration is unique by the diverse composition and facies types of sediments.     

含油气盆地蒸发盐矿物成因类型及其地质意义*

中国是一个多盐湖国家,然而盐湖研究主要集中于分析湖水化学性质、盐类物质来源和盐矿资源开发等,对盐类矿物沉积特征和埋藏成岩改造研究较少,造成从蒸发岩角度去理解古代盐湖盆地的油气富集规律较为困难。在广泛阅读国内外大型盐湖文献的基础上,笔者介绍了盐湖分类方案和蒸发岩中盐类矿物的主要成因类型,并总结了中国陆相含油气盆地中常见的硫酸盐、氯化物、含钠碳酸盐和硼酸盐的沉积—成岩过程及其古环境和古气候意义。同时,尝试利用盐湖沉积最新研究成果去探讨中国含油气盆地蒸发岩研究中存在争议或值得关注的问题,得出: (1)深部热液可为湖泊输送大量元素离子,但要在湖泊环境下富集大量蒸发岩,则(半)干旱气候和蒸发浓缩作用是前提条件;(2)易溶蒸发岩(如石盐)在沉积中心单层厚度大,而在斜坡—边缘区缺失,这是季节性气温变化和温跃层浮动引发“中心聚集效应”的结果;(3)温度可影响蒸发岩中盐类矿物溶解度、晶体结构形态和发育深度,而部分无水盐类矿物在常温常压下却无法结晶,这一现象可用来指示古地温和地层埋藏史;(4)碳酸盐型盐湖中的Na-碳酸盐种类可指示大气CO₂浓度和古温度。     

鸭绿江断裂带吉林段含油气盆地分布及演化

以地质、地球物理资料综合分析为基础,从含油气盆地的展布和盆地构造特征等方面探讨鸭绿江断裂带与含油气盆地形成、分布的内在联系。研究表明,鸭绿江断裂带控制的各盆地内存在广泛的湖相沉积与火山活动沿断裂带交替发生的现象。鸭绿江断裂带西南段盆地类型主要为断陷型盆地,东北段主要为断坳叠合型盆地。沿鸭绿江断裂带自西南向东北,盆地形成时代由老变新,盆地内部次级断裂活动程度逐渐减弱。受断裂带活动强弱的影响,西南段盆地具有更好的勘探前景。     

含油气盆地蒸发盐矿物成因类型及其地质意义*

中国是一个多盐湖国家,然而盐湖研究主要集中于分析湖水化学性质、盐类物质来源和盐矿资源开发等,对盐类矿物沉积特征和埋藏成岩改造研究较少,造成从蒸发岩角度去理解古代盐湖盆地的油气富集规律较为困难。在广泛阅读国内外大型盐湖文献的基础上,笔者介绍了盐湖分类方案和蒸发岩中盐类矿物的主要成因类型,并总结了中国陆相含油气盆地中常见的硫酸盐、氯化物、含钠碳酸盐和硼酸盐的沉积—成岩过程及其古环境和古气候意义。同时,尝试利用盐湖沉积最新研究成果去探讨中国含油气盆地蒸发岩研究中存在争议或值得关注的问题,得出: (1)深部热液可为湖泊输送大量元素离子,但要在湖泊环境下富集大量蒸发岩,则(半)干旱气候和蒸发浓缩作用是前提条件;(2)易溶蒸发岩(如石盐)在沉积中心单层厚度大,而在斜坡—边缘区缺失,这是季节性气温变化和温跃层浮动引发“中心聚集效应”的结果;(3)温度可影响蒸发岩中盐类矿物溶解度、晶体结构形态和发育深度,而部分无水盐类矿物在常温常压下却无法结晶,这一现象可用来指示古地温和地层埋藏史;(4)碳酸盐型盐湖中的Na-碳酸盐种类可指示大气CO₂浓度和古温度。     

中国含油气盆地深层勘探的主要进展与科学问题

中国沉积盆地深层的油气勘探实践不断取得进步,提出了与之密切相关的油气地质基础科学问题,凝练与分析这些问题将为深化我国沉积盆地深层地质研究与油气勘探提供引领。近年来,我国在深层海相碳酸盐岩、砂砾岩、火山岩、变质岩与页岩气等勘探领域中发现了一系列大型油气田,油气勘探发现深度推进到7 000～8 500m,勘探前景良好。但由于沉积盆地深层经历了长期构造演化,温、压场与应力场变化大,地质结构多变,油气成藏过程复杂,深层油气勘探面临着一系列关键地质问题,主要包括:中国大陆的形成演化及其构造-古地理,中国小克拉通地块之上海相盆地的原型及演化,中国沉积盆地的多期改造过程与叠加地质结构,沉积盆地的成因机制与动力学演化,深层烃源岩发育、成烃机制及其演化,深层储集体的形成机制与分布,深层油气成藏机制,多期叠加、改造背景下油气聚集与分布规律,深层页岩气赋存机制与分布规律,过程导向的沉积盆地4D动态模拟。我国沉积盆地深层的油气地质基础研究与实际应用需求相比有较大差距,需要立足于中国大陆实际,在盆地的形成演化过程与油气成藏动力学等方面进行深入探索,期望在活动论构造-古地理、三维构造复原、流体-岩石相互作用与四维动态模拟方面取得实质性进展。     

Uncertainty quantification of overpressure buildup through inverse modeling of compaction processes in sedimentary basins

This study illustrates a procedure conducive to a preliminary risk analysis of overpressure development in sedimentary basins characterized by alternating depositional events of sandstone and shale layers. The approach rests on two key elements: (1) forward modeling of fluid flow and compaction, and (2) application of a model-complexity reduction technique based on a generalized polynomial chaos expansion (gPCE). The forward model considers a one-dimensional vertical compaction processes. The gPCE model is then used in an inverse modeling context to obtain efficient model parameter estimation and uncertainty quantification. The methodology is applied to two field settings considered in previous literature works, i.e. the Venture Field (Scotian Shelf, Canada) and the Navarin Basin (Bering Sea, Alaska, USA), relying on available porosity and pressure information for model calibration. It is found that the best result is obtained when porosity and pressure data are considered jointly in the model calibration procedure. Uncertainty propagation from unknown input parameters to model outputs, such as pore pressure vertical distribution, is investigated and quantified. This modeling strategy enables one to quantify the relative importance of key phenomena governing the feedback between sediment compaction and fluid flow processes and driving the buildup of fluid overpressure in stratified sedimentary basins characterized by the presence of low-permeability layers. The results here illustrated (1) allow for diagnosis of the critical role played by the parameters of quantitative formulations linking porosity and permeability in compacted shales and (2) provide an explicit and detailed quantification of the effects of their uncertainty in field settings.     

Graben generation of major sedimentary basins

Regional isostatic adjustment to the load that fills the trough of a large graben will produce a surface depression that extends far beyond the boundaries of the load. Sediment infilling of this depression can lead to the development of a major sedimentary basin as the regional adjustment mechanism approaches isostatic equilibrium.     

含油气盆地多级序断裂网络体系拓扑特征：以济阳坳陷为例

断裂网络体系是含油气盆地的重要组成部分,这些复杂的断裂网络体系往往是由大量多级序断裂相互作用而成,难以通过几何学描述精确表达。因此,本文通过拓扑结构来表征含油气盆地中的多级序断裂网络,实现不同断裂间对比。在对拓扑参数,节点（独立I节点或连接的Y或X节点）和分支（I-I、I-C、C-C分支）统计的基础上,结合济阳坳陷不同应力背景下形成的多级序断裂网络与构造物理模拟实验进行对比,分析拓扑结构随应力变化的差异性。研究发现：1）单一拉伸背景下的相互作用仅限于断层侧接、叠覆时发生的连接（I节点和I-I或I-C控制）,断裂网络相对单一,连通性较差;而在多期拉伸背景下,拓扑特征逐渐以Y节点和C-C分支为主,断裂间连接程度随外界应力的改变而变化,断裂网络更加复杂,连通性较好;2）断裂网络的连通性受到C-C分支影响,C-C分支比例大则断裂相对复杂,连通性更好,C-C分支比例小则断裂网络相对简单,连通性较差。因此,明确断裂网络体系的拓扑结构有助于区分含油气盆地中单相和多相拉伸作用,从而对沉积盆地的地球动力学背景提供约束。

     

Crystalline basement and fold complex of the Volga-Ural, Pericaspian, and Fore-Caucasus petroliferous basins

3D models of apparent magnetization and density of rocks allow us to provide insights into the deep structure of the Volga-Ural, Pericaspian, and Fore-Caucasus petroliferous basins. In the Volga-Ural Basin, some Riphean rifts reveal close spatial relations to Paleoproterozoic linear zones, presumably of the rift nature as well. The structure of the Paleoproterozoic Toropets-Serdobsk Belt is interpreted in detail. Rocks with petrophysical properties inherent to basic volcanics are established in the pre-Paleozoic basement of the marginal zone of the Pericaspian Basin. These rocks locally spread beyond the boundary escarpment and may be regarded as a part of the Riphean plume-related basaltic province. It is shown that the Pericaspian Basin was formed on the place of a triple junction of Riphean rifts: the Sarpa and Central Pericaspian oceanic branches and the continental branch of the Pachelma Aulacogen. The drastically different petrophysical properties of the basement beneath Baltica and the Astrakhan Arch indicate that this arch is an element of the large terrane that was attached to Baltica in the Vendian. The suture along which the Astrachan Terrane is conjugated with the basement of the central and southern segments of the Karpinsky Ridge is traced beneath the Paleozoic complex. A system of northwest-verging thrust faults formed during the collision between Scythia and Eurasia is mapped in the basement of the junction zone between the Karpinsky Ridge and Scythian Platform (Terrane). According to geological data, this event took place in the Early Paleozoic.     

Predicted new large oil pools in the main petroliferous belt of the Lena-Tunguska province

Almost all the gas-oil and oil-gas fields in the Lena-Tunguska province (Siberian Platform) were discovered in the Baikit, Katanga, and Nepa-Botuobiya petroliferous regions, which form an E-W-striking band. The latter, named “the main petroliferous belt,” includes one giant and 11 large fields (by recoverable oil reserves).New large oil pools are predicted within the main belt. The prediction is based on the analysis of geological data and the quantitative estimation of hydrocarbon resources. Promising areas with large fields in the Baikit, Katanga, and Nepa-Botuobiya petroleum regions are substantiated.     

浅成岩体引发的流体超压与岩石破裂及其对成矿的制约

浅成岩体成矿系统是一类非常重要的复杂动力学系统。在这类系统中,由浅成岩体引发的流体超压以及因此而促发的岩石破裂是制约成矿的关键动力过程。文章在综合前人有关研究成果的基础上,结合对铜陵—安庆地区夕卡岩矿床的研究,从理论上对浅成岩体成矿过程中流体超压的重要性、形成机制及其对成矿作用的制约进行了系统论述。夕卡岩矿床与角砾岩间...     

含油气盆地深部高过成熟烃源岩古TOC恢复方法及其应用

根据烃源岩演化过程中残留生烃母质变化原理,建立了TOC恢复的数学地质模型,提出了TOC演化与各种主控因素之间的定量关系模式,通过对模式中各主控因素在自然条件下变化的特征取值,计算得到了TOC恢复系数,做出了泥质岩烃源岩和碳酸盐岩烃源岩在含不同类型干酪根情况下的TOC演化图版。这一方法的最大特色是避免了人为主观因素和高温压物理模拟实验条件可能带来的结果偏差。研究表明:随着热演化程度的增加,烃源岩内残留的TOC含量逐渐减少,在大量生排烃阶段(R_O=0.5％～2.0%)变化幅度最大;处于高过成熟阶段(R_O>1.2%)的烃源岩,其原始TOC恢复系数随R_O增大而逐渐增加,含Ⅰ型、Ⅱ型、Ⅲ型母质的泥质岩烃源岩TOC恢复系数分别可达3.0、2.0、1.4;含Ⅰ型、Ⅱ型、Ⅲ型母质的碳酸盐岩烃源岩TOC恢复系数分别可达3.2、2.2、1.5。论文例举了源岩TOC恢复在实际工程中的应用。     

松辽盆地古龙凹陷葡萄花油层超压成因

钻井资料揭示松辽盆地古龙凹陷葡萄花油层存在超压现象,但不存在欠压实现象;葡萄花油层上覆的嫩江组--二段泥岩和下伏的青山口组泥岩存在明显欠压实.声波时差数据计算的泥岩层超压与储层地层测试压力对比,证实油层超压主要来自超压系统内部的压力传递.油气产能与压力测试数据统计表明油层内部原油的热裂解对油层超压也有一定贡献;统计的超压油层的压力梯度大于静水压力梯度,说明储层内存在流动压力,青山口组和嫩江组现今仍在向葡萄花油层提供流体.     

Application of seismic exploration for direct search of multilayered petroliferous oil fields,Azerbaydzhan

In a multilayered, stratigraphically controlled, tectonically undisturbed deposit of oil-gas, definite seismic expressions of the petroliferous horizons were obtained by the “method of reflected waves,” with certain adaptations. The anomalously high absorption of high-frequency waves was found to be responsible for clarity of the seismic expressions.     

Interactions between basalts and oil source rocks in rift basins： CO2 generation

Basalts interbedded with oil source rocks are discovered frequently in rift basins of eastern China, where CO2 is found in reservoirs around or within basalts, for example in the Binnan reservoir of the Dongying Depression. In the reservoirs, CO2 with heavy carbon isotopic composition (δ13C>-10‰ PDB) is in most cases accounts for 40% of the total gas reserve, and is believed to have resulted from degassing of basaltic magma from the mantle. In their investigations of the Binnan reservoir, the authors suggested that the CO2 would result from interactions between the source rocks and basalts. As the source rocks around basalts are rich in carbonate minerals, volcanic minerals, transition metals and organic matter, during their burial history some of the transition metals were catalyzed on the thermal degradation of organic matter into hydrocarbons and on the decomposition of carbonate minerals into CO2, which was reproduced in thermal simulations of the source rocks with the transition metals (Ni and Co). This kind of CO2 accounts for 55%-85% of the total gas reserve generated in the process of thermal simulation, and its δ13C values range from -11‰- -7.2‰ PDB, which are very similar to those of CO2 found in the Binnan reservoir. The co-generation of CO2 and hydrocarbon gases makes it possible their accumulation together in one trap. In other words, if the CO2 resulted directly from degassing of basaltic magma or was derived from the mantle, it could not be accumulated with hydrocarbon gases because it came into the basin much earlier than hydrocarbon generation and much earlier than trap formation. Therefore, the source rocks around basalts generated hydrocarbons and CO2 simultaneously through catalysis of Co and Ni transition metals, which is useful for the explanation of co-accumulation of hydrocarbon gases and CO2 in rift basins in eastern China.     

沉积盆地超压系统内油气的生成与保存

沉积盆地内的超压系统是一个相对独立的封闭-半封闭体系,与油气生成、保存关系密切.超压系统内矿物介质、有机质、水相互作用过程以及有效应力对有机质演化的作用机理研究揭示了超压对有机质演化具有显著的阶段性和差异性,具体表现在:(1)压力的影响程度是有机质演化程度的函数;(2)超压/压力效应对有机质演化发生显著影响需要达到某一最小值,即门限值;(3)在有机质演化不同阶段发育的超压对生烃的影响不同;(4)同一超压系统内,不同类型有机质对超压的响应具有差异性.迄今,已经建立了超压/压力对有机质演化影响程度的定量化模型,包括化学动力学模型和热力学模型两类.化学动力学模型仍有许多需要改进的地方,如压力影响的阀值、指前因子和活化能随反应时间的变化规律等,相对而言,热力学模型似乎更简单、易用,但其可靠性和普适性还有待时间的检验.由于异常高压对超压系统储层内原油的热裂解反应具有抑制效应,有利于深部高温高压储层内液态烃的保存,因此,含油气盆地深部高温高压地层已成为一个较为有利的石油勘探领域.