中国深层和超深层碳酸盐岩油气藏形成分布的基本特征与动力机制及发展方向

随着油气资源对外依赖度加大,中国的油气勘探已经拓展到深层和超深层领域,并相继在中西部盆地发现了塔河、普光、安岳、靖边、顺北等一批大型油气田,展示出广阔的勘探前景。中国已探明的深层和超深层碳酸盐岩油气藏特征与全球的有很大差异,经典的油气地质理论指导这类油气田勘探遇到了前所未有的重大挑战,需要完善和发展。通过调研和比较全球已探明的碳酸盐岩和砂岩油气藏地质特征,发现它们的油气来源条件、油气藏形成条件、成藏动力、演化过程特征等类同;同时,发现碳酸盐岩和砂岩油气藏的矿物组成、孔隙度和渗透率随埋深变化特征、孔渗结构特征、储层物性下限、油气藏类型等有着很大不同。中国深层和超深层碳酸盐岩油气藏与全球的相比较具有五方面差异:地层年代更老、埋藏深度更大、白云岩储层比率更大、天然气资源比率更高、储层孔渗关系更乱。中国已经发现的深层碳酸盐岩油气藏成因类型可以归为五种:沉积型高孔高渗油气藏、压实成岩型低孔低渗油气藏、结晶成岩型低孔低渗油气藏、流体改造型高孔低渗油气藏、应力改造型低孔高渗油气藏;它们形成的动力学机制分别与地层沉积和浮力主导的油气运移作用、地层压实和非浮力主导的油气运移作用、成岩结晶和非浮力主导的油气运移作用、流体改造介质和浮力主导的油气运移作用、应力改造和浮力主导的油气运移作用等密切相关。中国深层和超深层碳酸盐岩油气藏勘探发展的有利领域和油气藏类型主要有三个:一是低热流盆地浮力成藏下限之上自由动力场形成的高孔高渗常规油气藏;二是构造变动频繁的叠合盆地内外应力和内部流体活动改造而形成的缝洞复合型油气藏;三是构造稳定盆地内局限动力场形成的广泛致密连续型非常规油气藏。改造类非常规致密碳酸盐岩油气藏是中国含油气盆地深层和超深层油气资源的主要类型:它们叠加了早期形成的常规油气藏特征,又具有自身广泛连续分布的非常规特征,还经受了后期构造变动的改造;复杂的分布特征,致密的介质条件和高温高压环境使得这类油气资源勘探开发难度大、成本高。      

Dynamic Field Division of Hydrocarbon Migration,Accumulation and Hydrocarbon Enrichment Rules in Sedimentary Basins

Hydrocarbon distribution rules in the deep and shallow parts of sedimentary basins are considerably different, particularly in the following four aspects. First, the critical porosity for hydrocarbon migration is much lower in the deep parts of basins: at a depth of 7000 m, hydrocarbons can accumulate only in rocks with porosity less than 5%. However, in the shallow parts of basins (i.e., depths of around 1000 m), hydrocarbon can accumulate in rocks only when porosity is over 20%. Second, hydrocarbon reservoirs tend to exhibit negative pressures after hydrocarbon accumulation at depth, with a pressure coefficient less than 0.7. However, hydrocarbon reservoirs at shallow depths tend to exhibit high pressure after hydrocarbon accumulation. Third, deep reservoirs tend to exhibit characteristics of oil (–gas)–water inversion, indicating that the oil (gas) accumulated under the water. However, the oil (gas) tends to accumulate over water in shallow reservoirs. Fourth, continuous unconventional tight hydrocarbon reservoirs are distributed widely in deep reservoirs, where the buoyancy force is not the primary dynamic force and the caprock is not involved during the process of hydrocarbon accumulation. Conversely, the majority of hydrocarbons in shallow regions accumulate in traps with complex structures. The results of this study indicate that two dynamic boundary conditions are primarily responsible for the above phenomena: a lower limit to the buoyancy force and the lower limit of hydrocarbon accumulation overall, corresponding to about 10%–12% porosity and irreducible water saturation of 100%, respectively.     

致密储层研究进展和热点问题分析

全球常规油气及非常规油气资源极为丰富,其中致密油气是非常规油气资源的主要类型,是当前非常规油气勘探的重点,也是未来接替常规油气资源的重要领域。致密储层具有油气资源量大、分布面积广、成岩作用强、单井产量较低、储层非均质性强等特点。在富含油气资源的致密储层中,具有良好物性的“甜点”是提高产量的有利勘探目标,其“甜点”主要包括两类,一类为异常高孔带,另一类为裂缝发育带。目前,致密储层的研究现状主要包括致密储层划分、地质特征、形成机理和有利储层预测等。近年来,“甜点”的形成机理和预测成为当前致密储层勘探开发的重要科学问题。因此,致密储层微观孔喉结构表征、致密储层裂缝发育识别表征是目前致密储层研究的热点领域及未来主要发展方向。     

珠江口盆地陆丰南地区古近系全油气系统特征与油气藏有序分布

珠江口盆地陆丰凹陷古近系发育多种类型的油气资源,尤其形成了具有多样特征的复合类和改造类油气藏,利用经典“含油气系统”理论难以解释油气藏成因机制和分布规律. 基于全油气系统新概念阐述了它们的形成分布. 结果表明,在古近系储层致密演化过程中,文昌组和恩平组两套烃源岩提供了早期排出烃、晚期排出烃、源内滞留烃三种原始烃量,源岩内部和周边砂岩储集层因成岩?压实差异发育了油气自由动力场、局限动力场和束缚动力场,全油气系统内三类原始烃量和3个动力场的耦合作用造成自下而上呈现出“页岩油气?致密油气?常规油气”的有序分布.这种规律性认识对于研究区不同类型油气资源分布预测和勘探具有重要的指导意义.      

非常规含气系统的研究和勘探进展

从含油气系统的观点出发，分别总结了煤层气、盆地中心气、裂缝型页岩气、浅层生物气和天然气水合物五类非常规含气系统的地质和地球化学特征，修改和补充了传统油气系统的概念，为天然气新领域的开拓和发展提供了新的思路。常规天然气藏为浮力驱动的存在于构造或地层圈闭中的独立气藏，而非常规天然气藏一般不是浮力驱动的聚集气藏，它们在区域上呈连续弥散的聚集，常常与构造和地层圈闭无关，因此，它们的成藏要素和过程与常规天然气藏有所区别。在煤层气和页岩气中，烃源岩既是储层，又是盖层且运移距离很短；储层多为低孔隙度、低渗透性的裂缝型储层，主要为毛细管力和水力封闭，大型煤层气藏可以出现在向斜构造中。     

中国非常规油气的战略思考

本文基于非常规油气的内涵,分析了致密砂岩油气和泥页岩油气的成藏地质条件,论述了非常规油气资源潜力巨大,指明中国非常规油气资源战略发展方向。研究表明,中国非常规油气藏是富集在近源储集体或烃源岩的低孔、低渗的微米级纳米级的储集空间中连续油气聚集,淡化了圈闭、油气藏边界的概念。依据成藏地质条件和油气资源潜力的差异,非常规油气藏主要指致密砂岩油气和泥页岩油气藏。致密砂岩油气藏多位于斜坡、坳陷区,具有广覆式有效烃源岩;源、储关联密切,多呈互层式;油气运移距离短,以非达西渗流为主;储集体渗透率、孔隙度极低。泥页岩油气藏圈闭概念淡化,典型的储源一体;多形成于盆地坳陷或斜坡区,泥页岩大面积连续分布;有机质丰度大,热演化成熟度高;多发育纹层结构,纳米级孔隙、裂缝储集系统;储集层脆性系数大,地层压力高。烃源岩呈现多时代、多层系、多沉积环境特征,从震旦系到第三系均有富含有机质的烃源岩发育,沉积环境囊括陆相海、陆交互相海相,非常规油气资源潜力巨大。常规与非常规油气在时、空域的紧密伴生和规律聚集,使得常规非常规油气在平面上和纵向上形成“有序聚集”体系。对“有序聚集”的不同类油气藏进行“整一化勘探、整一化部署、整一化开采”,实现常规非常规油气整一化科学有序开发,避免整体油气资源的破坏和遗漏;从而丰富油气地质理论,促进油气勘探由“点带面”向综合有序三维空间迈进。     

向斜成藏理论及其石油地质意义

传统的石油成藏理论适用于中高渗透储层,流体的渗流特征是达西渗流,主要作用力是浮力,油气分布在构造高部位或砂体高部位,主要是寻找圈闭。但是在低超低渗透储层和致密储层中,流体的渗流特征是非达西渗流,传统理论不再适用,油水不能发生正常的重力分异,流体在超压作用下以幕式排烃方式发生初次运移,石油在储层中运移要以非达西渗流方式通过变形才能缓慢通过,这种运移必然降低流速产生滞留效应导致石油在低部位大量滞留并聚集成连续油藏。这种滞留油藏的产生,可以形成背斜区圈闭含油、斜坡区相对高部位含水、而相对低部位却连续含油的油水倒置现象。由于滞留油藏无需构造和岩性边界圈闭,无需统一压力系统和油水边界,改变了传统上的圈闭找油模式,拓展了油气藏的概念,形成了低超低渗透储层、非常规、致密油等成藏研究的理论基础。向斜成藏理论的提出,是对传统石油成藏理论的重要补充,拓展了油气勘探领域,使油气勘探从构造高部位转向构造低部位,增大了石油资源量,对勘探开发具有重要的指导作用。     

隐蔽油气藏研究的难点和前沿

隐蔽油气藏已成为中国油气勘探的主要领域之一。随着勘探程度的提高,隐蔽油气藏勘探向复杂条件拓展,深层隐蔽油气藏发育与保存、不整合面结构与隐蔽油气藏分布、调整改造型隐蔽油气藏形成和保存机理成为隐蔽油气藏勘探和成藏机理研究的难点和前沿。深部存在活跃源岩和具有较高孔隙度和渗透率的储层是深层隐蔽油气藏成藏的基础。超压环境生烃作用动力学的研究进展提高了预测深层源岩生烃潜力的能力,已知的深层高孔隙度储层保存机理可成为预测深部储层孔渗条件的基础。不整合面结构特别是古土壤层的厚度及封闭能力、古土壤层之下半风化岩层的厚度及渗透率是研究与不整合面有关的隐蔽油气藏的关键。由于多期构造叠加、多期生烃和多期成藏,叠合盆地很多隐蔽油气藏经历了不同程度的调整改造,形成有成因联系的一系列调整改造型隐蔽油气藏,研究晚期构造与早期构造的叠加方式是预测调整改造型隐蔽油气藏的基础。准噶尔盆地中部,隐蔽油气藏同时具有埋藏深、不整合面结构复杂、多期成藏多期调整改造的特点,是建立复杂隐蔽油气藏成藏与勘探理论的天然实验室。     

Hydrocarbon Accumulation Conditions of Ordovician Carbonate in Tarim Basin

<正>Based on comprehensive analysis of reservoir-forming conditions,the diversity of reservoir and the difference of multistage hydrocarbon charge are the key factors for the carbonate hydrocarbon accumulation of the Ordovician in the Tarim Basin.Undergone four major deposition-tectonic cycles, the Ordovician carbonate formed a stable structural framework with huge uplifts,in which are developed reservoirs of the reef-bank type and unconformity type,and resulted in multistage hydrocarbon charge and accumulation during the Caledonian,Late Hercynian and Late Himalayan. With low matrix porosity and permeability of the Ordovician carbonate,the secondary solution pores and caverns serve as the main reservoir space.The polyphase tectonic movements formed unconformity reservoirs widely distributed around the paleo-uplifts;and the reef-bank reservoir is controlled by two kinds of sedimentary facies belts,namely the steep slope and gentle slope.The unconventional carbonate pool is characterized by extensive distribution,no obvious edge water or bottom water,complicated oil/gas/water relations and severe heterogeneity controlled by reservoirs. The low porosity and low permeability reservoir together with multi-period hydrocarbon accumulation resulted in the difference and complex of the distribution and production of oil/gas/water.The distribution of hydrocarbon is controlled by the temporal-spatial relation between revolution of source rocks and paleo-uplifts.The heterogenetic carbonate reservoir and late-stage gas charge are the main factors making the oil/ gas phase complicated.The slope areas of the paleo-uplifts formed in the Paleozoic are the main carbonate exploration directions based on comprehensive evaluation.The Ordovician of the northern slope of the Tazhong uplift,Lunnan and its periphery areas are practical exploration fields.The Yengimahalla-Hanikatam and Markit slopes are the important replacement targets for carbonate exploration.Gucheng,Tadong,the deep layers of Cambrian dolomite in the Lunnan and Tazhong-Bachu areas are favorable directions for research and risk exploration.     

准噶尔盆地玛湖凹陷三叠系源上砂砾岩扇—断—压三控大面积成藏模式

准噶尔盆地玛湖富烃凹陷下三叠统百口泉组新近发现了我国首个源上大面积连续型砂砾岩油藏群,是对全球"连续型"油气藏研究的新补充,但其成藏机理和模式并不很清楚。为加强对其的理论认识,并为下步勘探提供参考,基于油气生、储、盖、圈、运、保等基础石油地质条件,并结合油气藏特征,进行了成藏条件与成藏模式的综合研究。结果表明,优质充足的下二叠统风城组碱湖油气来源、规模有效的扇三角洲前缘砂砾岩储层、多重组合的扇三角洲平原致密砾岩、泥岩和断裂封盖保存、沟通良好的高角度断裂输导体系、平缓连续的构造背景奠定了大面积连续成藏的地质基础。在此背景下,高成熟的风城组所生成油气,在切穿烃源灶和储层的高角度压扭性断裂沟通下,优先充注物性相对好的扇三角洲前缘水下河道砂岩和砂质细砾岩,并且在地层异常高压促进下,控制着油气富集程度,使得油气成藏表现为大型缓坡浅水扇三角洲沉积控制下的源上扇-断-压三控大面积"连续型"。百口泉组油气藏具有的油质轻且含气、微裂缝广泛发育,以及异常高压等,决定了砾岩储层虽总体低孔低渗,但依旧能够高产。在油源断裂沟通的斜坡区上倾方向,叠合地层异常高压以及扇三角洲前缘水下河道砂砾岩的区域是下步有利勘探方向。     

湖南涟源凹陷构造演化与油气成藏研究

涟源凹陷经历了2个主要构造演化阶段:晚古生代海相碳酸盐岩夹碎屑岩盖层建造和中生代陆相沉积,现今的逆掩冲断构造样式和构造格局基本定型于燕山期。油气藏的形成经历了早、晚两期,早期形成于印支运动主幕,燕山运动主幕遭到破坏,部分经重新分配后形成次生气藏;晚期形成于燕山运动主幕以后,属原生油气藏。涟源凹陷中部褶断带的紧闭背斜是寻找次生气藏的首选区域,而宽缓向斜中的隐伏隆起则是寻找晚期原生油气藏的靶区。     

Yanshanian–Himalayan geodynamic transformation of the northwestern Junggar Basin,southwestern Central Asian Orogenic Belt (CAOB), and its significance for petroleum accumulation

The northwestern Junggar Basin in the southwestern Central Asian Orogenic Belt is a typical petroliferous basin. The widely distributed reservoirs in Jurassic–Cretaceous strata indicate that the region records Yanshanian–Himalayan tectonic activity, which affected the accumulation and distribution of petroleum. The mechanism of this effect, however, has not been fully explored. To fill the knowledge gap, we studied the structural geology and geochemistry of the well-exposed Wuerhe bitumen deposit. Our results indicate that deformation and hydrocarbon accumulation in the northwestern Junggar Basin during the Yanshanian–Himalayan geodynamic transformation involved two main stages. During the Yanshanian orogeny, a high-angle extensional fault system formed in Jurassic–Cretaceous strata at intermediate to shallow depths owing to dextral shear deformation in the orogenic belt. This fault system connected at depth with the Permian–Triassic oil–gas system, resulting in oil ascending to form fault-controlled reservoirs (e.g., a veined bitumen deposit). During the Himalayan orogeny, this fault system was deactivated owing to sinistral shear caused by far-field stress related to uplift of the Tibetan Plateau. This and the reservoir densification caused by cementation formed favorable hydrocarbon preservation and accumulation conditions. Therefore, the secondary oil reservoirs that formed during the Yanshanian–Himalayan tectonic transformation and the primary oil reservoirs that formed during Hercynian–Indosinian orogenies form a total and complex petroleum system comprising conventional and unconventional petroleum reservoirs. This might be a common feature of oil–gas accumulation in the Central Asian Orogenic Belt and highlights the potential for petroleum exploration at intermediate–shallow depths.     

烃源岩油气藏的圈层效应特征、差异成藏机制与有序分布模式

近源找油、进源勘探是未来油气勘探的方向。目前近源找油、进源勘探还面临很大的风险,主要原因是对烃源岩附近,尤其是烃源岩内的油气成藏条件、成藏机理、分布规律认识不到位。重新定义了烃源岩系统和烃源岩油气藏的概念,认为一个烃源岩系统就是一个独立的油气成藏单元,而烃源岩油气藏为赋存于烃源岩系统内的油气聚集。划分出常规油气藏与非常规油气藏两大类,泥岩裂缝油气藏等6种烃源岩油气藏,受构造控制,造就了它们独有的形成机制和特定的分布规律,形成了横向并列成圈、纵向有序成串、上下分层过渡、常规与非常规差异机理成藏和有序共生的圈层结构特征：即从内圈的深湖相页岩油气藏、浊积砂岩性油气藏,到中圈的半深湖相的致密油气藏,再到外圈的浅湖-半深湖过渡相的岩性尖灭油气藏分布序列。成藏机制上,也形成了内圈的页岩油气藏以原地连续性“滞留”与微运移“停留”,中圈的致密油气藏以大面积初次运移“停留”、外圈的岩性尖灭油气藏以浮力二次运移“截流”为特征的有序成藏机理序列。明确了页岩油气藏甜点区位于深盆区内圈前三角洲相带的具有“优势组构-滞留烃超越效应”的区域;致密油气藏甜点区位于深盆区中圈三角洲前缘相带的具有“优势孔缝耦合”的区域;...     

羌塘盆地昂达尔错白云岩古油藏地质特征及成藏条件

昂达尔错白云岩古油藏位于羌塘盆地南羌塘坳陷,是羌塘盆地规模最大的古油藏带,对该区油气勘探具有重要意义。依据铸体薄片、储层物性、沥青族组分分析,剖析了白云岩古油藏地质特征。分析结果表明,昂达尔错古油藏的储集体可归类为低孔—低渗型到中孔—中渗型储层,为较好储层类型;其石油族组分呈现饱和烃含量低、非烃+沥青质含量高的特征,为芳香沥青型、芳香环烷型石油。划分出两套生储盖组合,其中的下侏罗统曲色组—中侏罗统布曲组组合为较好的生储盖组合类型,具有较好的勘探远景。认为古油藏在晚侏罗世成藏,在喜马拉雅期遭受逆冲破坏。     

鄂尔多斯盆地苏里格气田西南部致密储层非均质性特征及对成藏的制约

致密砂岩气藏是我国非常规油气资源的重要组成,其储层非均质性严重影响了致密气成藏和甜点区优选,进而制约了气田高效开发。为进一步揭示储层非均质性成因及对致密气成藏的影响,选取鄂尔多斯盆地苏里格气田西南部山1段和盒8段致密储层为例,通过岩芯观察、扫描电镜、薄片鉴定、生产和测井分析等技术手段,研究储层非均质特征,探讨沉积作用和微观孔隙演化对非均质性和成藏的影响。结果表明,储层非均质性多表现为层内粒度的垂向韵律性、夹层的不均匀分布、渗透率的平面分布差异等;储层非均质性受沉积作用和成岩作用共同影响,沉积作用控制了水动力条件、砂体展布、厚度和砂体构型,储层微观非均质性受岩矿组构和孔隙演化影响;不同厚度和构型的复合砂体,多样的矿物组分、孔隙结构,致密气的选择性充注,共同造成了苏里格地区致密储层的非均质性及含气性差异。复合砂体的高孔渗部位是致密气开采的甜点区,但是在优选有利区时不应只关注这些厚层的高孔渗砂体,也应关注规模小、非均质性稍强的透镜状砂体,需要充分考虑到储层非均质性对致密气成藏的影响。     

Logging evaluation of deep multi-type unconventional gas reservoirs in the Songliao basin,northeast China: Implications from continental scientific drilling

Multi-type unconventional gas-bearing reservoirs with different lithologies and gas accumulation potential occur in the deep part of the Songliao basin. However, the reservoirs are non-homogeneous, the gas components differ substantially, and not all types of gas-bearing reservoirs have been identified or evaluated. The International Continental Scientific Drilling Program (ICDP) is used as an example to conduct qualitative and quantitative evaluations of deep multi-type unconventional gas-bearing reservoirs using conventional and specialized logging data. The core test data are used to determine the physical properties. The porosity and permeability are compared and analyzed using different methods and models. The results show that the reservoirs have low to ultra-low porosity and ultra-low permeability. Based on the comparison of the rock mechanical parameters and mineral composition, brittleness evaluation parameters are proposed for different types of deep reservoirs in the study region. The mineral brittleness index is highly consistent with the brittleness index based on rock mechanics. An identification method for deep multi-type gas-bearing reservoir and a classification approach for different gas properties are established based on the logging response and parameter interpretation. The methane gas reservoirs have low density (DEN) and low compensated neutron logging (CNL) values and high acoustic (AC) time difference and high resistivity (RT) values. The CO₂ gas reservoirs have lower RT values and higher CNL values than the hydrocarbon gas reservoirs. The comprehensive analysis of deep gas source rock conditions and of the source-reservoir relationship provides insights for the evaluation of deep multi-type unconventional gas reservoirs. The discovery of high hydrogen content is of significant importance for developing new areas for deep natural gas exploration.     

中国非常规油气勘探与研究新进展

全球油气勘探目标的转移和石油地质学的发展,具有从毫-微米孔喉的圈闭油气,逐渐向纳米孔喉的连续型油气聚集发展的趋势。近十年非常规油气资源在全球能源格局中的地位愈发重要,致密气、煤层气、重油、沥青砂等已成为勘探开发的重点领域,致密油成为亮点领域,页岩气成为热点领域。中国致密气、页岩气、致密油、煤层气等非常规油气资源勘探开发取得重要突破,油页岩、天然气水合物、油砂矿等有重要进展。中国非常规油气研究也取得重大进展,陆相敞流湖盆大型浅水三角洲砂体、湖盆中心砂质碎屑流沉积和湖相碳酸盐岩等,提供了湖盆中心储集体形成和分布的理论依据;创新发展了连续型油气聚集理念,明晰了连续型油气聚集的10个基本地质特征和2项关键标志,为大面积非常规油气规模勘探开发奠定了理论基础;系统表征了致密油气储层的纳米级微观孔喉结构,首次发现了纳米孔喉中油气的赋存,推动了纳米孔喉中油气流动机制和分布规律的研究。随着全球石油工业和纳米等技术的快速发展,提出了"纳米油气"概念,并指出这是未来石油工业的发展方向,需要发展纳米油气透视观测镜、纳米油气驱替剂、纳米油气开采机器人等换代技术,油气智能化时代即将到来。     

塔里木盆地北部奥陶系油气相态及其成因分析

塔里木盆地北部地区奥陶系是最重要的勘探层系,油气资源丰富;同时油气相态复杂多样,既有凝析气藏、正常油藏,也有稠油油藏、沥青等。通过对油气藏形成演化与保存过程的系统分析,结合油气地球化学和流体包裹体等分析数据,发现油气相态的多样性与油气多期次充注与次生蚀变作用有关。提出塔北隆起的东部奥陶系存在三期油气充注过程,分别发生在加里东运动晚期-海西早期、海西运动晚期、喜马拉雅运动晚期,原油主要来源于中、上奥陶统烃源岩,天然气主要来自与寒武系烃源岩有关的液态烃的裂解;塔北隆起的中西部奥陶系的油气充注主要发生在海西运动晚期。塔北奥陶系油藏形成以后,经历了三期明显的调整改造过程:海西早期构造抬升导致志留-泥盆系遭受剥蚀,东部源自寒武系油气的古油藏遭受破坏,形成沥青;三叠系沉积前的晚海西运动,使得奥陶系生源的油藏大范围遭受降解稠化;晚喜山期,来自于满加尔坳陷的天然气自东向西充注,致使隆起东部早期形成的油藏发生强烈的气侵改造,形成次生凝析气藏。而中西部奥陶系油藏在三叠系沉积前遭受降解稠化后,一直处于沉降深埋过程,油藏得到有效保存;由于成藏时间较早,轻质组分散失较多,气油比极低,油质较稠。研究认为,油气相态的多样性主要受晚海西期构造运动的抬升造成的生物降解作用和喜马拉雅晚期构造运动造成的天然气自东向西大规模充注对油藏进行气洗改造两大过程的控制。     

Alteration and Reformation of Hydrocarbon Reservoirs and Prediction of Remaining Potential Resources in Superimposed Basins

<正>Complex hydrocarbon reservoirs developed widely in the superimposed basins of China formed from multiple structural alterations,reformation and destruction of hydrocarbon reservoirs formed at early stages.They are characterized currently by trap adjustment,component variation, phase conversion,and scale reformation.This is significant for guiding current hydrocarbon exploration by revealing evolution mechanisms after hydrocarbon reservoir formation and for predicting remaining potential resources.Based on the analysis of a number of complex hydrocarbon reservoirs,there are four geologic features controlling the degree of destruction of hydrocarbon reservoirs formed at early stages:tectonic event intensity,frequency,time and caprock sealing for oil and gas during tectonic evolution.Research shows that the larger the tectonic event intensity,the more frequent the tectonic event,the later the last tectonic event,the weaker the caprock sealing for oil and gas,and the greater the volume of destroyed hydrocarbons in the early stages.Based on research on the main controlling factors of hydrocarbon reservoir destruction mechanisms,a geological model of tectonic superimposition and a mathematical model evaluating potential remaining complex hydrocarbon reservoirs have been established.The predication method and technical procedures were applied in the Tazhong area of Tarim Basin,where four stages of hydrocarbon accumulation and three stages of hydrocarbon alteration occurred.Geohistorical hydrocarbon accumulation reached 3.184 billion tons,of which 1.271 billion tons were destroyed.The total volume of remaining resources available for exploration is～1.9 billion tons.     

湖相烃源岩中的火山—热液深源物质与油气生成耦合关系研究进展*

陆内湖相烃源岩系是中国含油气盆地广泛发育的一类组分复杂且富含有机质的细粒沉积岩。随着非常规油气资源需求量日益增加,该岩系被作为致密油或页岩油层系受到广泛关注。然而,其极细的粒度增加了精细岩石学、矿物学研究难度,使它长期被简单视为陆源沉积岩。研究发现,该岩系中发育丰富的火山喷发及热液喷流产生的深源物质,并与油气的生成和富集表现出了极强的耦合关系。因此,探索深源物质如何参与烃源岩形成并影响油气生成亟待深入研究。作者详细总结并探讨了国内外近年来关于湖相烃源岩成因以及火山—热液活动带来的深源物质与油气形成关系的现阶段新发现与认识。并结合笔者研究团队基于新疆三塘湖盆地二叠系芦草沟组烃源岩的新发现,采用精细的岩石学、矿物学方法,结合无机和有机地球化学等方法,初步开展了该耦合关系的机理研究。认为火山—热液深源物质参与了烃源岩的沉积与成岩作用,并与正常湖相沉积物共同影响着油气的形成。建议重新认识湖相烃源岩的物质组成,从而拓展陆相生油理论,同时为同类型非常规油气资源勘探开发提供理论指导。