Diagenesis-porosity evolution and“sweet spot”distribution of low permeability reservoirs:A case study from Oligocene Zhuhai Formation in Wenchang A sag,Pear River Mouth Basin,northern South China Sea

The characteristics of low permeability reservoirs and distribution of sweet spots in the Oligocene Zhuhai Formation of Wenchang A sag, Pearl River Basin were investigated by core observation and thin section analysis. The study results show that there develop the fine, medium and coarse sandstone reservoirs of tidal flat–fan delta facies, which are of mostly low permeability and locally medium permeability. There are two kinds of pore evolution patterns: oil charging first and densification later, the reservoirs featuring this pattern are mainly in the third member of Zhuhai Formation between the south fault zone and the sixth fault zone, and the pattern of densification first and gas charging later is widespread across the study area. Strong compaction and local calcium cementation are the key factors causing low permeability of the reservoirs in the Zhuhai Formation. Thick and coarse grain sand sedimentary body is the precondition to form "sweet spot" reservoirs. Weak compaction and cementation, dissolution, early hydrocarbon filling and authigenic chlorite coating are the main factors controlling formation of "sweet spot" reservoir. It is predicted that there develop between the south fault and sixth fault zones the Class Ⅰ "sweet spot" in medium compaction zone, Class Ⅱ "sweet spot" in nearly strong compaction zone, Class Ⅲ "sweet spot" reservoir in the nearly strong to strong compaction zone with oil charging at early stage, and Class IV "sweet spot" reservoir in the strong compaction and authigenic chlorite coating protection zone in the sixth fault zone.

Pore and fracture characteristics of Cretaceous tight reservoir and its control effect on hydrocarbon accumulation in the Liuhe Basin

Tight oil and gas in the Cretaceous has been found in the Liuhe Basin,but the rules of tight reservoir and oil and gas accumulation are not clear.This paper discusses the developmental characteristics and evolution law of pores and fractures in the Cretaceous tight reservoir in the Liuhe Basin,and reveals its controlling effect on tight oil and gas accumulation.The results show that intercrystalline pores,intergranular pores and dissolution pores are scattered and only developed in shallow tight reservoirs,while microfractures are developed in both shallow and deep layers,which are the main type of reservoir space in the study area.The results of mercury intrusion porosimetry and nitrogen gas adsorption show that with the increase of depth,the proportion of macropores(microcracks)increases,while the proportion of micropores decreases.There are two stages of microfractures developed in the study area,corresponding to the initial fault depression stage from late Jurassic to early late Cretaceous and compressional uplift at the end of late Cretaceous.According to the principle of“inversion and back-stripping method”,combined with the data of optical microscopy and inclusions,the time of each key diagenesis and its contribution to porosity are revealed,and the porosity evolution history of reservoirs in different diagenetic stages is quantitatively restored.The porosity reduction rate of compaction can reach more than 80%,which is the main reason for reservoir densification.The relationship between pore evolution history and oil and gas accumulation history reveals that during the oil and gas filling period of the Xiahuapidianzi Formation(90-85 Ma),the reservoir porosity is only 1.15%,but the development of microfractures in the first stage of the reservoir is conducive to oil and gas accumulation.

Coupling relationship between reservoir diagenesis and hydrocarbon accumulation in Lower Cretaceous Yingcheng Formation of Dongling,Changling fault depression,Songliao Basin,Northeast China

The Lower Cretaceous Yingcheng Formation in the southern Songliao Basin is the typical tight oil sandstone in China.In order to better predict the petrophysical properties of the tight sandstone reservoirs in the Lower Cretaceous Yingcheng Formation,Songliao Basin,Northeast China,the diagenesis and porosity evolution was investigated using a suite of petrographic and geochemical techniques including thin section analysis,scanning electron microscopy,mercury intrusion and fluid inclusion analysis,on a set of selected tight sandstone samples.Combined with the histories of burial evolution,organic matter thermal evolution and hydrocarbon charge,the matching relationship between reservoir porosity evolution and hydrocarbon accumulation history is analyzed.The result showed that the tight sandstone reservoirs characterized of being controlled by deposition,predominated by compaction,improved by dissolution and enhanced by cementation.The hydrocarbon accumulation period was investigated using a suite of hydrocarbon generation and expulsion history,microfluorescence determination and temperature measurement technology.According to the homogenization temperature of the inclusions and the history of burial evolution,Yingcheng Formation has mainly two phases hydrocarbon accumulation.The first phase of oil and gas is charged before the reservoir is tightened,the oil and gas generated by Shahezi source rocks enter the sand body of Yingcheng Formation,influenced by the carrying capability of sand conducting layer,oil and gas is mainly conducted by the better properties and higher connectivity sand body and enriched in the east,which belongs to the type of densification after hydrocarbon accumulation.The second phase of oil and gas charge after densification,which belongs to the type of densification before the hydrocarbon accumulation.

Modes of Shale-Gas Enrichment Controlled by Tectonic Evolution

The typical characteristics of shale gas and the enrichment differences show that some shale gases are insufficiently explained by the existing continuous enrichment mode. These shale gases include the Wufeng–Longmaxi shale gas in the Jiaoshiba and Youyang Blocks, the Lewis shale gas in the San Juan Basin. Further analysis reveals three static subsystems（hydrocarbon source rock, gas reservoirs and seal formations） and four dynamic subsystems（tectonic evolution, sedimentary sequence, diagenetic evolution and hydrocarbon-generation history） in shale-gas enrichment systems. Tectonic evolution drives the dynamic operation of the whole shale-gas enrichment system. The shale-gas enrichment modes controlled by tectonic evolution are classifiable into three groups and six subgroups. Group I modes are characterized by tectonically controlled hydrocarbon source rock, and include continuous in-situ biogenic shale gas（Ⅰ_1） and continuous in-situ thermogenic shale gas（Ⅰ_2）. Group Ⅱ modes are characterized by tectonically controlled gas reservoirs, and include anticline-controlled reservoir enrichment（Ⅱ_1） and fracture-controlled reservoir enrichment（Ⅱ_2）. Group Ⅲ modes possess tectonically controlled seal formations, and include faulted leakage enrichment（Ⅲ_1） and eroded residual enrichment（Ⅲ_2）. In terms of quantity and exploitation potential, Ⅰ_1 and Ⅰ_2 are the best shale-gas enrichment modes, followed by Ⅱ_1 and Ⅱ_2. The least effective modes are Ⅲ_1 and Ⅲ_2. The categorization provides a different perspective for deep shale-gas exploration.

Tectonic Evolution and Hydrocarbon Potential in Northern Area of the South Yellow Sea

The northern area of the South Yellow Sea, located in the offshore region of China, resulted from the continental-continental collision orogeny during the Mesozoic and can be divided into four stages in terms of tectonic evolution： （1） pre-orogenic passive continental margin stage （Z-T2）; （2） foreland basin stage corresponding with the late phase of the Sulu （苏鲁） orogeny （J3-K）; （3） post-orogenic intracontinental rifted basin stage （K2t-E）; and （4） regional subsidence and coverage stage （N-Q）. Based on detailed investigation and study of the intracontinental rifted basin, hydrocar- bon source rocks of Late Cretaceous Taizhou （泰州） Formation distributed well in the basin, and four reservoir-cap combinations as well as numerous trap structures were found. As a result, the geological conditions would be excellent for reservoir formation in the basin, and the oil resource amount is estimated at about 20×10^8 t, which makes the basin a major target for hydrocarbon exploration in the South Yellow Sea.

准噶尔盆地东道海子凹陷二叠系平地泉组烃源岩特征及热演化史模拟

基于钻井、录井、测井及烃源岩分析测试等资料,对准噶尔盆地东道海子凹陷二叠系平地泉组烃源岩的生烃潜力和热演化史进行了系统研究。研究结果表明:(1)准噶尔盆地东道海子凹陷二叠系平地泉组烃源岩主要为深灰色、灰黑色泥岩,颜色深且厚度普遍较大,自东北部斜坡区向凹陷中部厚度逐渐增大,并向西部莫索湾凸起逐渐减小,最大泥岩厚度可达536 m。(2)研究区平地泉组烃源岩有机质丰度综合评价为中等—极好,纵向上以平一段有机质丰度最高,平面上以凹陷东北部滴南7井区和滴南19井区最高;平地泉组有机质类型主要为Ⅱ_(2)—Ⅲ型,少部分为Ⅱ_(1)型,纵向上以平二段有机质类型最好,平面上凹陷区烃源岩有机质类型主要为Ⅱ_(1)—Ⅱ_(2)型。(3)热演化史模拟结果显示,凹陷区和斜坡区烃源岩分别在晚三叠世和晚侏罗世达到生烃高峰,现今分别处于高成熟阶段和成熟阶段。(4)研究区发育“下生上储”和“自生自储”2类油气藏,其中平地泉组烃源岩与上乌尔禾组储集层形成“下生上储”油气藏,平二段和平一段的优质烃源岩与湖盆边缘的小型扇三角洲沉积在平地泉组内部形成“自生自储”油气藏,二者油气勘探潜力均较大。

塔里木盆地兰尕与和田河断裂带变形特征及成藏演化模式

塔里木盆地中部发育北北东向—近南北向“半走滑-半逆冲”的“Y”字形逆冲滑脱断裂,其构造样式与邻区断裂差异较大,两侧断裂体系也不同,目前对其形成机制和构造演化特征的认识尚不清楚。通过对和田河与兰尕断裂带的构造解析,研究其形成机制与演化特征;通过与塔河油田兰尕断裂带油气成藏特征对比,分析和田河断裂带油气运移聚集特征。研究表明:兰尕及和田河半走滑-半逆冲的“Y”字型逆冲滑脱断裂带形成于加里东晚期,向下收敛为走滑断裂,向上逆冲至志留纪地层内,形成断背斜。区域地应力是这2条断裂带形成的主要原因。早奥陶世末,受西南、东南和北部3面应力作用,塔北隆起形成大规模北北东向和北北西向走滑断裂,巴楚隆起形成北北东向走滑断裂。加里东运动晚期,受东昆仑和南天山洋挤压作用,形成向下收敛为走滑断裂、向上逆冲至志留纪地层内的逆冲滑脱断裂,并切割走滑断裂,使逆冲断裂上盘走滑断裂再活动,形成的缝网规模及破碎程度远比下盘及其他区域大。在后期构造运动作用下,逆冲断裂带内走滑断裂继承发育,并错断逆冲断裂。兰尕断裂带内发育两种有利成藏模式:①主干北北东向走滑断裂横向交切上倾断溶体油气成藏模式;②油气沿次级北北东向走滑断裂分段富集的断溶体油气成藏模式。海西运动晚期,和田河构造带沿主干断裂充注的油气向次级北北东向走滑断裂控制的缝洞型储层侧向调整,发育断溶体油气藏,油气沿断裂带分段富集。因此,南部背斜区北北东向断溶体为有利勘探目标。

渤东凹陷新生代伸展-走滑叠合断裂时空差异演化模式及控藏效应

以三维地震精细解释为基础,通过构造剖面恢复,系统分析了渤东凹陷新生代伸展-走滑叠合断裂的时空差异演化特征及控藏作用。研究结果表明:(1)渤东凹陷新生代广泛发育以NNE向为主干、NE向为派生、NW向为叠加的伸展-走滑叠合断裂体系,可划分为强伸展-弱走滑断裂和强走滑-弱伸展断裂2类;整体具有深浅分层、南北分段的特征,纵向上,古近系主要发育强伸展-弱走滑断裂,断裂大而稀,新近系—第四系主要发育强走滑-弱伸展断裂,断裂小而密;平面上,同一断裂在不同段的构造组合样式存在差异。(2)研究区新生代伸展-走滑叠合断裂的演化主要表现为北部断裂活动强度“早强晚弱”,中部断裂继承性持续发育,南部断裂活动强度“早弱晚强”;演化模式分为初始断陷(孔店组—沙四段沉积期)、强烈断陷(沙三段—东营组沉积期)和走滑坳陷(馆陶组—平原组沉积期)3个阶段,初始断陷阶段,NNE—NE向强伸展与弱走滑叠合,NE向强伸展-弱走滑断裂为主控,NW向先存断裂活化,分割凹陷;强烈断陷阶段,NNE—NE向强伸展与弱走滑叠合,NNE向强伸展-弱走滑断裂变为主控,NW向断裂活动减弱或停止;走滑坳陷阶段,NNE向强走滑与弱伸展叠合,断裂不控制沉积,但对地层展布具有调整作用。(3)研究区伸展-走滑叠合断裂的发育演化与油气成藏密切相关,整体具有“早期伸展控源、晚期走滑控运、多期叠加控圈”的特征,东部斜坡带是油气运聚的有利区。

渤海湾盆地济阳坳陷东部深层砂砾岩多类型油气藏成藏机理及模式

渤海湾盆地济阳坳陷东部深层砂砾岩油气展现出良好的勘探前景,深层油气藏类型多样且成藏地质条件与中、浅层差异显著,其差异化地质特征的形成机理制约着深层油气勘探开发的进程。采用镜下薄片观察、储层流体包裹体分析和盆地模拟等方法,分析了深层储层孔隙类型及地层压力存在差异的原因,进而建立了济阳坳陷深层砂砾岩多类型油气成藏模式。结果表明:(1)储层成岩演化揭示了深层储层不同孔隙类型的形成机制,深层砂砾岩储层中原生粒间孔隙的保存为早期油气充注和超压流体共同作用的结果,烃源岩生烃充注酸性流体引发的溶蚀反应是次生溶蚀孔隙形成的关键,储层中超压环境有助于微裂缝发育,形成孔-缝型储集空间。(2)深层流体超压演化受到生烃作用和沉积过程的控制,超压环境的形成取决于保存条件,构造-岩性油气藏中压力的分布受断-砂输导体系调配。在深层常压-弱超压储层中,源-储剩余压力差为稳定和充足的成藏动力;而在超压储层中,源-储剩余压力差随着时间推移逐渐减弱。在断层发育区和垂向连通性强的砂体中浮力是油气二次运移、调整的主要动力。(3)基于生烃-储层-压力对济阳坳陷东部深层砂砾岩油气成藏的耦合控制作用,建立了多期叠置近岸水下扇油气相态垂向分异型、近岸水下扇泥岩顶部及侧向联合封堵型、近岸水下扇-浊积扇近源成藏型3种油气成藏模式。济阳坳陷深层多类型砂砾岩油气藏成藏机理和模式的揭示为后续深入勘探奠定了坚实的基础。

特提斯洋与古亚洲洋协同演化控制下的塔里木台盆区油气富集效应

显生宙特提斯洋和古亚洲洋2大构造域演化历史对塔里木盆地产生了巨大的影响,其效应包括原型盆地的形成与沉积充填过程及油气成藏与调整改造等。原特提斯洋和古亚洲洋分别经历了扩张、俯冲-消减和关闭-碰撞造山过程。特提斯域经历了原特提斯、古特提斯和新特提斯3个阶段,具有此消彼长的关系。古亚洲洋在新元古代—古生代多陆-岛-洋的格架下经历了复杂的伸展—聚敛过程。受特提斯洋(昆仑-阿尔金分支洋)和古亚洲洋(南天山洋分支)协同演化控制,塔里木盆地经历了新元古代—早古生代和晚古生代—新生代2个从伸展—聚敛的巨型盆地旋回,与海平面升降和气候旋回匹配,形成了优质烃源岩、多类型规模性储层和盖层,构成了油气形成的优越物质基础。特提斯洋和古亚洲洋多圈层协同演化控制的油气富集效应体现在:①多类型盆地原型与后期构造改造决定了塔里木台盆区不同部位油气成藏与富集的差异性;②北部坳陷广泛分布的优质烃源岩,是塔北—顺托—塔中地区大型油气富集区形成的基础;③多期构造运动伴随的构造破裂与古岩溶作用造就了断控缝洞型和岩溶缝洞型2类各具特点且规模发育的储集体;④区内构造与地温场差异演化决定了油气聚集区内油气相态与次生改造的规律性变化。台盆区大型古隆起和不整合面、走滑断裂带、高能相带及其叠加区是油气有利目标区。

致密砂岩储层成岩过程及其与油气充注的关系——以鄂尔多斯盆地富县地区长8储层为例

储层致密化与油气充注的时间过程及其相互关系在勘探评价中具有关键作用。将铸体薄片观察、X射线衍射、扫描电镜及核磁共振相结合,细致分析了储层砂岩成岩过程与孔隙演化。结合已有油气成藏资料,综合建立了储层砂岩埋藏-成岩-孔隙演化-油气充注的演化序列。结果表明:富县地区长8储层类型以长石砂岩和岩屑长石砂岩为主,孔喉关系复杂,为低-特低孔及特低-超低渗致密储层。早成岩阶段A期,长8储层经历机械压实(压溶)作用(Φ_(2)=21.6%),少量胶结物生成,距今192.5~152.0 Ma(J_(1)~K_(1)),Ⅰ期油气充注;早成岩阶段B期,大量胶结物生成(Φ_(3)=6.9%);中成岩阶段,距今152~126 Ma(K_(1)),Ⅱ期油气充注(主成藏阶段);晚期盆地构造抬升(Φ_(3)=10.8%),距今65.0~36.5 Ma(E_(1)),Ⅲ期油气充注。成岩过程导致油气充注的选择性与储层含油的差异性,研究成果对于寻找富县地区长8储层的“甜点区”具有重要的实际意义。

Association of Sandstone-Type Uranium Mineralization in the Northern China with Tectonic Movements and Hydrocarbons

In the continental basins of Northern China(NC),a series of energy resources commonly co-exist in the same basin.As the three typical superimposed basins of different genesis in the NC,the Junggar,Ordos,and Songliao basins were chosen as the research objects.The favorable uraniumbearing structures are generally shown as a basin-margin slope or transition belt of uplifts with the development of faults,which are conducive to a fluid circulation system.The Hercynian,Indosinian,and Yanshanian movements resulted in the development of uranium-rich intrusions which acted as the significant uranium sources.The main hydrocarbon source rocks are developed in the Carboniferous,Permian,Jurassic and Cretaceous.The mature stage of source rocks is concentrated in the Jurassic–Cretaceous,followed by the multi-stage expulsion events.Influenced by the India-Eurasian collision and the subduction of the Pacific Plate,the tectonic transformation in the Late Yanshanian and Himalayan periods significantly influenced the sandstone-type uranium mineralization.The hydrocarbon reservoirs are spatially consistent with sandstone-type uranium deposits,while the hydrocarbon expulsion events occur in sequence with sandstone-type uranium mineralization.In the periphery of the faults or the uplifts,both fluids met and formed uranium concentration.The regional tectonic movements motivate the migration of hydrocarbon fluids and uranium mineralization,especially the Himalayan movement.

准噶尔盆地西北缘下二叠统油气储层中火山物质蚀变及控制因素

通过岩心分析、显微镜下观察(常规、铸体薄片和扫描电镜)、岩石地球化学分析测试等技术手段,以准噶尔盆地西北缘下二叠统油气储层为实例,研究了火山岩、火山碎屑岩和火山岩屑质砂砾岩中的火山玻璃、火山碎屑、长石以及辉石、角闪石等火山物质的低温-埋藏蚀变作用。镜下观察发现,在含火山物质油气储层中,常见对储集空间具有重要影响的自生矿物主要有绿泥石、沸石(包括方沸石、片沸石和浊沸石)、方解石、钠长石和自生的石英。结合共生关系、元素组成和元素迁移,分析了自生矿物的微观特征和成因,建立了火山物质蚀变的成岩演化序列,可以概括为:①火山玻璃水化—蒙脱石化—沸石化及各种沸石的转化——钠长石化;②铁镁矿物影响的绿泥石化;③长石蚀变向绿泥石和方解石转化,后期发生钠长石化。在研究区,火山物质的蚀变和自生矿物的析出与中-基性的母岩物质组成密切相关,并受地层温度、压力、孔隙水的化学性质控制。研究火山物质蚀变的产物、蚀变过程及控制因素,能够明确含火山物质的油气储层质量差异机理,为优质储层预测提供科学的依据。

富有机质泥页岩高压生烃模拟与孔隙演化特征

针对深层高演化气页岩储层勘探和潜力评价的需求,通过高温高压模拟实验探讨了泥页岩在深层高演化阶段的成烃规律和孔隙演化。研究表明,高压条件下富有机质泥页岩中的纳米级微孔隙随温度和压力的升高不断增加,增加高峰与气态及液态烃产率高峰相一致,并导致页岩孔隙率升高,但进入高—过成熟阶段后页岩孔隙率将随模拟条件的进一步升高而降低。与微孔隙相反,页岩中的微米级毛细孔和巨孔随模拟温度或压力的升高不断减少,指示深层条件不利于游离气的储存,而该阶段微孔隙和表面积的显著增加,可弥补随温度和压力升高吸附能力下降引起的页岩吸附态天然气的减少,从而使深层页岩仍然具有较高的页岩气潜力。模拟样品黄铁矿、白云石等组分中发现大量次生微孔隙,证明页岩碎屑及矿物基质在深层演化阶段也能形成丰富的次生微孔隙,作为烃源岩页岩在演化过程中能形成大量酸性流体,有利于次生孔隙的发育。

鄂尔多斯盆地延长组低渗透致密岩性油藏成藏机理

以层序地层学为指导,从成藏条件解剖入手,从孔隙演化的角度分析鄂尔多斯盆地中生界上三叠统延长组低渗透致密岩性油藏成藏机理,归纳其成藏演化模式。延长组低渗透致密岩性油藏分布于优质烃源岩范围内,湖相重力流沉积与三角洲前缘沉积为主要储集砂体类型。延长组低渗透致密砂岩在早期成藏期具有高孔高渗的特点,早期生成的油气在浮力作用下正常成藏,中后期成藏过程中经历了持续压实致密过程;后期主生烃期生成的原油在浮力和源储压差共同作用下沿先前残余路径以浸润方式运聚,达到致密条件时,油气停止运移。晚侏罗世—早白垩世中期,油气在高孔隙砂岩中近源多点面状充注大面积成藏,油气从湖盆中心向四周运移;早白垩世晚期,砂岩储集层成岩作用加强,储集层发生致密化。晚白垩世之后,受西倾东翘的构造挤压抬升运动影响,形成现今低渗透致密岩性油藏。

四川地区志留系页岩气成藏的地质背景

从构造演化入手,以四川地区志留系龙马溪组底部的黑色泥岩为研究对象,探讨其页岩空间分布特征、生烃作用历程及页岩气的成藏过程。研究认为:四川地区龙马溪组黑色页岩是一套富含有机质的烃源岩,属Ⅰ型干酪根,具有厚度大、埋藏适中、有机质成熟度高等有利条件,为页岩气在该地区的形成和聚集成藏,并形成大规模的气藏提供可能;威远、泸州、宜宾和自贡区域龙马溪组页岩气资源潜力很大。

准噶尔盆地腹部二叠系、三叠系储集层特征及烃类侵位对深部储集层物性的影响

利用薄片、扫描电镜、储集层物性、黏土矿物X衍射等资料,分析了准噶尔盆地腹部二叠系、三叠系储集层岩石学特征,进而探讨了烃类侵位对其物性的宏观影响及微观机理。大量观察与分析表明,研究区储集层以岩屑砂岩为主,具有火山岩岩屑含量高等特点,其储集物性总体具有低孔、低渗的特点,但差中有优,4000m以下深度物性明显变好。研究区深部含油储集层物性明显好于不含油储集层,深层方解石、浊沸石和自生伊利石含量随含油级别的提高呈降低趋势,说明原油的侵入在一定程度上抑制了自生矿物的形成与演化,导致深部含油储集层中自生矿物的含量减少,从而使含油储集层物性获得明显改善。

低潜山反转构造演化、成藏体系与勘探——以胜利油区孤北低潜山为例

隐蔽油气藏的勘探是一切大中型油气田油气勘探开发中晚期所经历的必然阶段。胜利油区孤北低潜山已经取得一定的勘探成果 ,但基本上都是局限于低潜山之上的第三系地层中 ,潜山构造本身还没有取得突破。在勘探程度日益增高的胜利油区 ,类似的勘探目标由于埋藏深、经历了多期构造叠加和破坏 ,研究程度较低 ,但它将是下一步勘探的重点目标和方向。运用大量的实际资料 ,对潜山地层发育及构造特征进行了研究 ,通过构造演化过程的分析 ,论述了反转构造与油气聚集的关系 ,预测总结了油气藏类型和油气分布特征 ,划分了 3个成藏组合 ,指出了勘探潜力和方向。

川中—川东南地区震旦系—下古生界沥青来源及成烃演化

据实测实验数据分析了川中及川东南地区典型构造上勘探井震旦系—下古生界泥岩及沥青样品的生物标志化合物的特征,证实源岩的沉积环境主要为具有一定盐度的还原环境,生物多来自于低等水生生物的菌藻类。川中震旦系—下古生界和川东南震旦系储层沥青主要来自寒武系泥岩;川东南下古生界储层沥青则为寒武系和志留系的混合来源。利用Karweil方法分析了川中地区高科1井寒武系烃源岩的成烃史;采用磷灰石裂变径迹技术与Easy%Ro模型联合模拟恢复了川东南地区丁山1井的生烃史;对比分析表明,川东南寒武系烃源岩成熟时间、主生油及主生气期均早于川中寒武系烃源岩。

大民屯凹陷压力场演化及其成藏意义

利用Basin 2盆地模拟软件模拟了辽河坳陷大民屯凹陷 5条横向地质剖面的压力演化史 ,并探讨了其超压形成机制及油气成藏意义。模拟结果显示 :①大民屯凹陷超压较明显 ,超压主要出现在沙三段及沙四段 ,超压演化总体上遵循“无超压—陡增—平缓上升—最高值—下降—最低值”这一规律 ;②大民屯凹陷超压的演化分为两个阶段 :沙三段和沙一、二段沉积期 (距今 43 0～3 6 9Ma)为超压积累阶段 ,东营沉积期及其以后 (3 6 9Ma至现今 )为超压释放阶段。综合研究结果表明 :①不均衡压实和生烃作用是大民屯凹陷超压发育的主要机制 ,断层对超压的积累与释放起着重要的控制作用 ;②大民屯凹陷的超压对油气成藏起着积极的作用 ,提供了油气运移的动力和通道 ,提高了高分子量组分特别是“蜡”的排出效率 ,同时也是泥岩刺穿构造的诱发因素 ,并可成为下伏油气藏的优质盖层条件。