中国油气盆地砂岩储层的成岩压实机制分析

埋藏成岩作用理论认为碎屑沉积物的压实作用是由上覆岩柱的有效应力产生的,但该理论解释不了我国油气盆地砂岩储层的成岩作用特征.我国油气盆地复杂的地质条件导致碎屑岩成岩压实机制的多样性,它既有上覆岩柱引起的压实效应(静岩压实效应),也有盆地热流控制的压实效应(热压实效应)、地层流体性质影响的压实效应(流体压实效应)以及构造变形引起的压实效应(构造压实效应).静岩压实效应、流体压实效应和热压实效应是沉积盆地中普遍的砂岩成岩作用现象;构造控制成岩作用贯穿于整个成岩过程,本文的构造活动指施加于岩石的构造变形作用,它引起的压实效应见于我国西部地区的油气盆地.物理模拟的实验结果表明静岩压实速率为0.013～0.138%/MPa,模拟温度提高,其压实速率变大.热压实效应具有深度加大,热效应压实量(或热效应压实速率)减小;以及盆地的地温梯度差距加大,热效应压实量(或热效应压实速率)增大的特点;在相同的地层温度(T)下,低地温梯度地区的砂岩孔隙度是高地温梯度地区的e0.077+0.0042×T倍.流体压实效应具有粒级越粗,其压实效应越强;以及深度变大,一定岩性储层的流体压实效应变弱,而不同粒级之间储层流体压实效应的差距变大的特点.构造压实效应反映在多个方面,侧向构造挤压和基底隆升加快砂岩的压实进程,侧向构造挤压应力每增加1.0MPa,砂岩压实量平均增加0.1051%;而晚期构造推覆使下伏砂岩储层保持较高孔隙度.     

Heat flow in Indian Gondwana basins and heat production of their basement rocks

Temperatures have been measured in eight boreholes (ranging from 260 to 800 m in depth) in five Gondwana basins of the Damodar and Son valleys. With the aid of about 250 thermal conductivity determinations on core samples from these holes, heat flow has been evaluated. Measurements of radioactive heat generation have been made on samples of Precambrian gneisses constituting the basement for the Sonhat (Son valley) and Chintalapudi (Godavari valley) basins.Heat-flow values from all of the Damodar valley basins are within the narrow range of 69–79 mW/m². The value from the Sonhat basin (107 mW/m²) is significantly higher. The generally high heat flows observed in Gondwana basins of India cannot be attributed to the known tectonism or igneous activity associated with these basins. The plots of heat flow vs. heat generation for three Gondwana basins (Jharia, Sonhat and Chintalapudi) are on the same line as those of three regions in the exposed Precambrian crystalline terrains in the northern part of the Indian shield. This indicates that the crust under exposed regions of the Precambrian crystalline rocks as well as the Gondwana basins, form an integral unit as far as the present-day geothermal character is concerned.     

深层—超深层碎屑岩储层非均质性特征与油气成藏模式

深层—超深层地质条件下,储层的孔渗物性特征和流体动力连通关系决定了油气在储层中的流动状态,这也就决定了油气运移的动力条件和聚集成藏的机理与过程。本文基于对深层—超深层碎屑岩储层结构非均质性的研究,认识深层—超深层油气运聚成藏机制和过程,总结油气多期复合成藏模式,探索深层—超深层油气分布规律。碎屑岩储层普遍存在强烈的非均质性,受到沉积结构构造及成岩作用控制,表现出空间结构性特征,在埋藏至深层—超深层的过程中经历了差异性的成岩演化和油气充注。结构非均质性储层中的油气总体向上倾方向运移,受储层中砂体分布、隔夹层结构以及连通方式的影响,油气运移路径的分布极不均匀,在储层中任何部位都可能聚集,并可能继续运移到有利圈闭中富集。在深埋过程中,多期多幕的构造变动促使深层—超深层储层中已聚集的油气向着上倾方向运移调整,或沿着断裂向上运移调整至中—深层与之相关的有效储层中运移、聚集。深层—超深层勘探具有更为广泛的目标选择,洼陷区和斜坡区都可能成为有利勘探区域。现实的深层—超深层油气勘探新领域包括：构造高点油气藏向供源方向的拓展,深层—超深层烃源由断裂调整至中深层—超深层的次生油气聚集,深层—超深层与油气源...     

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.     

Naturally propped fractures caused by quartz cementation preserve oil reservoirs in basement rocks

Much silica precipitation in oil reservoirs occurred in the presence of hydrocarbons, evidenced by the entrapment of oil fluid inclusions in quartz. Also, silica in sedimentary basins is commonly precipitated at oil‐window temperatures. This spatial and temporal relationship between oil and quartz precipitation aids the entry of oil into fractured reservoirs, including fractured basement. Where quartz is precipitated as fracture linings, the fractures are propped open by bridging quartz crystals, creating high fracture porosity and permeability. Evidence from fossil fractured reservoirs shows a large proportion of oil residue is in such propped open fractures.     

Terrestrial sediment yield and the lifetimes of reservoirs, lakes, and larger basins

Water reservoirs, lakes, and larger basins, including their drainage areas, represent sedimentologically closed to semi-closed denudation-accumulation systems. The mean rates of mechanical denudation, DR_me, and clastic sedimentation, SR_me, are related by the ratio of the drainage/lake area, A_d/A_l. If the latter is known, DR_me (or the specific sediment yield SY in t per km²/a) can be calculated from SR_me, or vice versa. The best data for modern SY mainly come from the sediment fills of artificial reservoirs. Small drainage areas of mountainous regions show SY values up to two orders of magnitude higher than lowlands and approximately one order higher than larger regions of mixed relief. This is also true of arid to semi-arid zones which often provide approximately as much sediment (SY) as humid temperate and even tropical zones of comparable relief. Lithology and climate (river runoff) also may play some role for SY from catchments of limited size. The importance of these factors is exemplified by perialpine lakes and two East African lakes. Sediment yields gained from some large reservoirs compare well with long-term denudation rates derived from geological studies (e.g., the Tarbela dam reservoir along the Indus River). In many other cases, human activities have raised SY by factors of 2–10, locally up to >100. Artificial reservoirs in mountainous regions with SY in the range of 300–2000?t?per?km²/a tend to become filled within several tens to hundreds of years; some have even shorter lifetimes. Perialpine lakes of the Alps and British Columbia are strongly affected by delta prograding and have lifetimes mostly between 15 and 40?ka. Closed lake systems in deep morphological depressions (Lake Bonneville, Aral Sea, northern Caspian Sea) have a high potential for sediment storage up to the level of spillover and therefore can persist over long time periods. Basins with markedly subsiding basin floors (lakes of the East African rift zone, the southern Caspian Sea, and the Black Sea, both on oceanic crust) can survive for many Ma in the future, despite relatively high terrigenous input.     

Genetic identification of natural gases from shallow reservoirs in some oil- and gas-bearing basins of China

Natural gases of shallow reservoirs with the carbon isotopic compositions of methane ranging from -50‰ to -60‰ (PDB) were considered as mixed gases of biogenic and thermogenic origins previously and some of them were considered as low-mature (or low temperature thermogenic) gases lately. In this paper natural gases with the carbon isotopic compositions of methane in the above range were identified using the molecular and stable carbon isotopic compositions of methane, ethane and propane. The mixed gases of biogenic and mature thermogenic origins display the characteristics of δ 13 C1 ranging from -50‰to -60‰,δ13C2 ＞ -35‰,Δvalues (δ13C3 -δ13C2) ＜ 5‰ and C1/∑C2 ratios ＜ 40. Immature to low-mature gases display the characteristics of δ 13 C1 ranging from - 50‰ to - 60‰, δ13 C2 ＜- 40‰,Δ values (δ13C3 -δ13C2) ＞7‰, and C1/∑C 2 ratios ＞60.     

多旋回盆地叠合-复合控藏在常规非常规天然气勘探中的实践

四川盆地是我国典型的多旋回盆地,更是最重要的天然气基地,发现了大量的常规、致密砂岩、页岩气田。具有海相、海陆过渡相、陆相垂向叠加与平面分区明显、纵向多期构造运动叠加改造的特点,形成了全盆地、全层系含气。本文以普光气田、涪陵页岩气田和中江致密砂岩气为实例,阐述了叠合-复合控藏的概念,即叠合盆地油气成藏和富集的各种要素均受相互关联的多种因素的控制,不同要素间既有时间上的累加和空间上的叠置,也有横向上地质体因某种原因而结合在一起,比如构造与岩性体、构造与地层等。叠合控制油气的形成与演化,复合控制油气的富集与定位,进一步论述明确多旋回盆地叠合-复合控藏研究内容对油气勘探研究与实践具有重要的指导意义。通过对四川盆地典型大型气田实例剖析,表明四川盆地大型气田均是受多旋回盆地叠合-复合控藏的结果,即叠合控制油气的形成与演化,复合控制油气的富集与定位。本文系统分析总结四川盆地大型气田油气形成、成藏与富集规律,结合四川盆地勘探开发现状,针对四川盆地多旋特征提出油气勘探三个方面的重点研究内容:(1)构造古地理研究,厘清构造格局、储层、烃源和圈闭空间的叠合、复合关系以及对油气形成的控制作用;(2)区域地质构造演化研究,明确不同期次构造叠合关系以及对成油、成气、油气富集的控制作用;(3)构造分级与控藏研究,精细构造分级明确不同级次构造对气水关系、富集、储层改造控制作用。     

断拗型盆地构造-沉积模式与隐蔽性油藏——以西藏伦坡拉盆地古近系为例

伦坡拉盆地为西藏地区唯一发现工业油流的古近系断拗型陆相残留盆地。勘探实践表明,早期对该盆地构造-沉积模式与油气成藏关系认识不够一定程度上制约了勘探,为理清二者关系并落实有利勘探方向,本文对该盆地的构造、沉积特征及成藏条件进行分析。盆地南北向可划分为缓坡带、深凹带、陡岸带3个构造带;识别出河流-冲积扇、扇三角洲、湖泊、水下扇4种沉积体系,其中在缓坡带发育河流-冲积扇、扇三角洲沉积体系,深凹带发育湖相沉积体系,陡岸带发育水下扇沉积体系;盆地存在2种沉积体系组合:缓坡带(河流)冲积扇-扇三角洲-滨浅湖相沉积体系组合,陡岸带水下扇-半深湖(深湖)-滨浅湖相沉积体系组合;可用"双向物源、缓坡扇三角洲、陡坡水下扇"构造-沉积模式解释。在缓坡带,应寻找扇三角洲前缘岩性隐蔽性油藏;在陡岸带,有可能发现构造-岩性复合型隐蔽性油藏。盆地具有多种潜在有利勘探目标类型,展现出较好的勘探前景。     

含煤盆地煤储层后期改造形式及对煤层气选区影响--以华北克拉通选区为例

阐述了改造型含煤盆地煤储层被改造的两种形式；煤体结构的改造及构造煤的形成原因；后生充填物对煤层孔隙的改造及形成原因。提出了以构造煤发育程度作为改造型含煤盆地改造强度的一个指标。概述了华北克拉通盆地由中生代剪压应力转化为新生代剪张应力和拉张应力，而在盆地内形成以挤压构造为主到伸展构造为主的演化历程，及不同构造类型的区域分布，指出这种演化极易形成构造煤和后生充填物。提出将华北克拉通含煤盆地分为3种改造类型及其分布区域，分析了各自区域的煤储层物性及对煤层气开发选区的影响。提出应重视鄂尔多斯盆地侏罗纪煤层的煤层气．研究与开发．     

A new regional tectonic map of the consolidated crystalline basement of sedimentary basins and near-surface fold structures of the Ural region

A new approach to the tectonic zoning of the consolidated crystalline basement and near-surface fold structures, taking into account the specific features of the structure of the Earth’s crust is suggested. As a result, a new regional tectonic map of these complexes of the Ural region was created.     

Linking the Sulu UHP belt to the Korean Peninsula: Evidence from eclogite, Precambrian basement, and Paleozoic sedimentary basins

Considerable debate on whether and how the Sulu Orogenic Belt extends eastward to the Korean Peninsula has remained over the past decade. New results reported here include the following: (1) an eclogite and retrograded eclogite-bearing complex (Hongseong Complex) is discovered in South Korea, in which the eclogite occurs as lenses in circa  810–820 Ma granitic gneiss. SHRIMP zircon dating of the eclogite yields  230 Ma for the metamorphic age and  880 Ma for the protolith age; (2) The basement of the Rangnim, Gyeonggi and Yeongnam massifs have affinities to the basement of the North China Block (NCB). However the Gyeonggi Massif encloses a minor amount of large or small slabs of the Hongseong Complex that are similar to the rocks of the Sulu Belt. (3) Two main Paleozoic basins within the Rangnim and Gyeonggi massifs have a similar Paleozoic tectono-stratigraphy to the NCB. (4) The Imjingang and Ogcheon belts do not exhibit any metamorphic characteristics of collisional orogenic belts. Based on these facts, we propose a crustal-detachment and thrust model and suggest that the collision belt between the Yangtze Block (YB) and NCB (Sino–Korea Craton) is preserved along the western margin of the Korean Peninsula. The lower part of the UHP metamorphosed lithosphere of the YB was subducted under the Korean Peninsula and not uplifted to the surface. The lower crust of the YB (the Hongseong Complex) was detached from the subducted lithosphere and thrust over the Korean Peninsula, and inserted into the basement rocks of the Gyeonggi Massif. The upper crust of the YB possibly was detached from the lower crust and overthrusted along the Honam and Chugaryong shear zones. The Imjingang and Ogcheon belts possibly represent the detached upper crust of YB and their present occurrences are controlled by a Mesozoic strike–slip shear structure. All these detached lower and upper crustal slabs were strongly deformed during the Late Jurassic and Early Cretaceous tectonic event leading to their present geological distribution and characteristics.     

Cavitation in oil-gas reservoirs of the crystalline basement from the well logging data on the White Tiger field in Vietnam

The methods and results of logging the oil reservoirs in the crystalline basement of the White Tiger field are characterized. The data on 46 wells that exposed the basement of the Central arch were used to determine the values and to establish the regularities of the changes in the general and secondary cavitation (porosity).     

A strontium, oxygen and hydrogen isotopic composition of brines, Michigan and appalachian basins, Ontario and Michigan

⁸⁷Sr/⁸⁶Sr ratios of brine from samples from the Michigan and Appalachian Basins, in Ontario and Michigan, covering the stratigraphic interval from the Cambrian to Mississippian, vary from 0.708 to 0.711. With the exception of the salt units of the Salina Formation (Silurian), most values are greater than seawater for the time in question, indicating water-rock interaction. The sources of the radiogenic Sr has not been identified. All samples plot below the GMWL in δ¹⁸O−δ²H space, with the Cambrian and Ordovician samples closest to the line. Mixing of brines meteoric and glacial (Pleistocene) water is indicated in some cases. The more concentrated brines from each stratigraphic unit show a very narrow spread in values. All the Ordovician brines show a narrow range over a 200 km area for Sr, O and H isotopes, indicating extensive lateral migration of the fluids.Strontium in the brine has not equilibrated isotopically with its host rock. In some cases the late-stage minerals saddle dolomite, calcite and anhydrite have the same ⁸⁷Sr/⁸⁶Sr ratios as the brine, indicating that they precipitated from the brine in isotopic equilibrium.     

地表溶蚀盆地-地下岩溶联合成库条件分析——以弄岩水库为例

水资源已成为人类社会及经济发展的重要制约因素,国内外都在积极探索不同气候、不同地质条件下水资源的合理开发利用。受地下岩溶发育及气候影响,岩溶地区的地表及地下水资源在时间、空间上分布极不均匀,旱涝并存,通常以单一拦蓄地表水或直接抽取地下水来应对,存在较大局限性。文章在总结分析前人的研究成果上,结合弄岩水库,利用水文系列资料进行相关分析,找出地表水与地下水之间的变量关系及相应可开采水资源量;查明地下岩溶蓄水条件,在岩溶通道设置地下拦蓄工程,实现地表水与地下水联合开发,并利用地表及与地下岩溶水库的调蓄功能均衡供水,有效解决旱涝问题,水资源得以最大化合理利用。     

Lithosphere,crust and basement ridges across Ganga and Indus basins and seismicity along the Himalayan front,India and Western Fold Belt,Pakistan

Spectral analysis of the digital data of the Bouguer anomaly of North India including Ganga basin suggest a four layer model with approximate depths of 140, 38, 16 and 7 km. They apparently represent lithosphere–asthenosphere boundary (LAB), Moho, lower crust, and maximum depth to the basement in foredeeps, respectively. The Airy’s root model of Moho from the topographic data and modeling of Bouguer anomaly constrained from the available seismic information suggest changes in the lithospheric and crustal thicknesses from ∼126–134 and ∼32–35 km under the Central Ganga basin to ∼132 and ∼38 km towards the south and 163 and ∼40 km towards the north, respectively. It has clearly brought out the lithospheric flexure and related crustal bulge under the Ganga basin due to the Himalaya. Airy’s root model and modeling along a profile (SE–NW) across the Indus basin and the Western Fold Belt (WFB), (Sibi Syntaxis, Pakistan) also suggest similar crustal bulge related to lithospheric flexure due to the WFB with crustal thickness of 33 km in the central part and 38 and 56 km towards the SE and the NW, respectively. It has also shown the high density lower crust and Bela ophiolite along the Chamman fault. The two flexures interact along the Western Syntaxis and Hazara seismic zone where several large/great earthquakes including 2005 Kashmir earthquake was reported.The residual Bouguer anomaly maps of the Indus and the Ganga basins have delineated several basement ridges whose interaction with the Himalaya and the WFB, respectively have caused seismic activity including some large/great earthquakes. Some significant ridges across the Indus basin are (i) Delhi–Lahore–Sargodha, (ii) Jaisalmer–Sibi Syntaxis which is highly seismogenic. and (iii) Kachchh–Karachi arc–Kirthar thrust leading to Sibi Syntaxis. Most of the basement ridges of the Ganga basin are oriented NE–SW that are as follows (i) Jaisalmer–Ganganagar and Jodhpur–Chandigarh ridges across the Ganga basin intersect Himalaya in the Kangra reentrant where the great Kangra earthquake of 1905 was located. (ii) The Aravalli Delhi Mobile Belt (ADMB) and its margin faults extend to the Western Himalayan front via Delhi where it interacts with the Delhi–Lahore ridge and further north with the Himalayan front causing seismic activity. (iii) The Shahjahanpur and Faizabad ridges strike the Himalayan front in Central Nepal that do not show any enhanced seismicity which may be due to their being parts of the Bundelkhand craton as simple basement highs. (iv) The west and the east Patna faults are parts of transcontinental lineaments, such as Narmada–Son lineament. (v) The Munghyr–Saharsa ridge is fault controlled and interacts with the Himalayan front in the Eastern Nepal where Bihar–Nepal earthquakes of 1934 has been reported. Some of these faults/lineaments of the Indian continent find reflection in seismogenic lineaments of Himalaya like Everest, Arun, Kanchenjunga lineaments. A set of NW–SE oriented gravity highs along the Himalayan front and the Ganga and the Indus basins represents the folding of the basement due to compression as anticlines caused by collision of the Indian and the Asian plates. This study has also delineated several depressions like Saharanpur, Patna, and Purnia depressions.     

Rifted arch basins and post-breakup rim basins on passive continental margins

In its evolution by plate divergence to a passive continental margin, a continental arch marked by narrow rift valleys (intra-arch basins) and flanked by broad basins (inter- and extra-arch basins) is most likely to break up along a rift valley boundary fault. The resulting dismembered arch at the continental margin is a rim that constitutes the oceanward flank of a rim basin, and the rim basin succeeds one or other of the basins related to the previous arch. In offshore Western Australia, the juxtaposition of Mesozoic reservoir rock at a rift shoulder and source rock of the succeeding rim basin provide a mechanism for concentrating a large gas deposit.     

全球含硫化氢天然气的分布特征及其形成主控因素

含硫化氢天然气是天然气资源的重要组成部分,也是硫磺的重要来源之一,其全球资源量巨大,分布范围广泛。高含硫化氢天然气主要分布在北美洲、欧洲、前苏联、中东、亚洲等地区的大型油气田中。这些油气田的油气地球化学性质各不相同,硫化氢成因复杂,硫化氢含量变化较大,从0.1%～98%都有分布。通过对全球各大含硫化氢油气田进行系统的调查研究,发现含硫化氢的油气藏主要分布在三叠纪和石炭纪碳酸盐岩储层中,构造位置位于被动大陆边缘;碳酸盐岩储集体物性较好,盖层通常由膏盐与岩盐组成,膏盐的位置对硫化氢的产生影响很大;良好的盖层也是大量硫化氢气体得以聚集保存的重要条件。大量硫化氢的产生一般出现在温度等于或高于120℃的储集体中,并伴随有大量的二氧化碳产生。