松辽盆地白垩纪微体生物群分布特征与富烃源岩层的形成

松辽盆地是我国白垩纪最大的陆相含油气盆地,晚白垩世两次大的湖侵事件导致了微体生物群的繁盛和富烃源岩层的形成。在论述松辽盆地白垩纪微体古生物群分布特征的基础上,着重阐述了以微体生物为核心的松花江生物群的发育与富烃源岩层形成的关系。认为大型富营养湖泊的发育为松花江生物群的繁盛创造了良好的外部条件,而湖盆内繁盛的微体生物群则为富烃源岩层的形成提供了丰厚的物质基础,与此同时,长期继承性深水构造凹陷和非补偿沉积则是富烃源岩层形成的有利场所。

烃源岩层系地层破裂情况的定量评价及应用

地层破裂情况定量评价、破裂岩石对地层输导能力的促进作用研究,对非常规油气藏勘探具有重要的作用。通过同围压条件下岩石破裂压力与烃源岩层系围压影响范围的对比,对渤海湾盆地济阳坳陷渤南—四扣地区烃源岩层系静岩压力作用下的岩石破裂情况进行了定量研究,并实测了烃源岩层系岩石破裂对输导能力的影响。在此基础上提出了围压、破裂压力、破裂后输导能力综合比对研究地层破裂情况的方法。渤南—四扣区域烃源岩层系中,古近系沙河街组三段上、中亚段,区域较深部位砂岩、泥页岩岩层普遍产生破裂,中部位砂岩岩层产生破裂;沙河街组三段下亚段,区域中、深部位岩层普遍产生破裂;沙河街组四段上亚段,区域中、深部位岩层普遍产生破裂、高部位部分砂岩岩层产生破裂。破裂的地层渗透率大幅提升,能够作为有效输导通道。上述方法对现有“甜点”评价提供了有力补充。

论烃源岩层系含油气系统

含油气系统(PS)作为一种研究对象、研究思路和研究方法,是常规油气勘探评价的重要手段之一,但对非常规油气研究却有一定的局限性。为了探寻源内非常规油气勘探评价研究思路和方法,在回顾含油气系统概念发展历程的基础上,对比分析了烃源岩体系和非烃源岩体系油气特征和差异,形成了一套适合于源内滞留烃准连续—连续聚集型油气藏的研究思路和研究方法,提出了烃源岩层系含油气系统(SRPS)概念,论证了其研究思路、研究内容及基本内涵,总结了4项研究关键技术。研究成果丰富了源内非常规油气勘探评价理论体系,为源内非常规油气勘探评价提供了指导。

鄂尔多斯盆地延长组长7段富铀烃源岩的铀赋存状态与富集机理

鄂尔多斯盆地晚三叠世延长组长7段是一套深湖相富铀烃源岩,岩石富含草莓状黄铁矿、有机质纹层、胶磷矿等。本文通过电子探针、LA-ICPMS、逐级化学提取、α径迹蚀刻等方法研究了长7段烃源岩中铀的赋存状态,发现烃源岩中约50%以上的铀赋存于胶磷矿中,20%以上的铀以吸附形式赋存于有机质中。因此,胶磷矿在铀的富集过程中起了重要作用。岩石地球化学参数表明长7段烃源岩沉积于缺氧环境,频繁的火山喷发活动为长7段富铀烃源岩层提供了丰富的铀源。在缺氧的沉积环境下,成岩作用早期底层水和裂隙水的交换作用使铀从凝灰岩中向长7段黑色页岩中迁移,赋存于胶磷矿和有机质纹层中。总之,缺氧的沉积环境、丰富的铀、高含量的有机质及胶磷矿共同促进了铀在鄂尔多斯盆地上三叠统延长组长7段富铀烃源岩中的形成。

油气沿断层垂向运移特征及主控因素分析——以东海盆地西湖凹陷平湖斜坡为例

东海盆地西湖凹陷平湖斜坡油气纵向富集差异受断层控制作用明显,但断层活动期与成藏期匹配关系差,油气成藏时断层处于不活跃期(简称静止断层),明确油气沿静止断层垂向运移特征及影响因素,可以为西湖凹陷或相似地区油气勘探提供理论依据。为此,综合测井、录井、地震等资料和包裹体均一温度及盐度、岩石热解等分析测试数据,研究平湖斜坡油气供烃层系与成藏期次,确定油气沿静止断层垂向运移特征及影响因素。结果表明,平湖斜坡供烃层系为宝石组和平湖组好—优质的成熟烃源岩,油气纵向上主要富集于平中段—平上段,具有下生上储的运聚特征。存在玉泉组—柳浪组沉积期和三潭组沉积期至今两期油气充注,断层主要活动时间为宝石组—龙井组沉积期,与成藏期匹配关系差,油气晚期沿静止断裂带发生了垂向运移。油气能够沿静止断层垂向运移的影响因素包括断裂带宽度、烃源岩层压力和断裂带排替压力。研究区断裂带宽度分布在138~288m之间,与油气垂向运移距离呈正相关关系。烃源岩层压力经历了复杂的演化过程,成藏期压力略低于现今,但已发育弱超压或超压,现今和成藏期压力系数越高,油气垂向运移距离越大。断裂带排替压力主要分布在0.2~3.5MPa之间,与油气垂向运移距离呈负相关关系。基于3个影响因素与油气垂向运移距离的相关关系,建立了断层垂向输导能力定量评价公式,评价结果与油气最大运移距离具有明显的正相关性,据此确定了平湖斜坡有利勘探层系为F2和F5断层附近的平湖组和花下段。

松辽盆地南部伏龙泉断陷烃源岩特征研究与评价

伏龙泉断陷位于松辽盆地东南隆起区,是东南隆起区次一级构造单元,为一独立的生烃凹陷。经历了多期构造运动和多期油气生成、运移、成藏,由此造成油气源对比的复杂性,而对于有效烃源岩层的确定和分布,直接关系着油气资源量的预测和勘探方向的选择,因而,对伏龙泉断陷烃源岩的深入研究具有重要的现实与实践意义。

松辽盆地生油门限重新厘定及其意义

对松辽盆地滨北地区、主力烃源岩区（齐家－古龙凹陷和三肇凹陷）、主力烃源岩层（白垩系青山口组一段、青二段－青三段）成烃转化率－埋深关系曲线及R0－埋深关系曲线进行了系统分析，重新厘定盆地生油门限深度。结果表明，松辽盆地主力烃源岩的生油门限深度可能为1400～1700m，而不是过去认为的1200m左右。生油门限深度的变化对盆地各地区资源潜力和勘探方向具有不同的影响：对于主力烃源岩区，生油门限变深，将使评价所得生、排烃量减少，但对资源潜力没有明显影响，可能影响对勘探方向和有利目标的评价；对于烃源岩埋藏相对较浅的滨北地区，生油门限变深，勘探潜力、勘探方向、有利目标评价将受到至关重要的影响；对于盆地内抬升剥蚀量较大的东南隆起区，生油门限变浅，约为700m，将明显提升朝阳沟阶地、长春岭背斜和宾县－王府地区的勘探潜力。

柴窝堡凹陷石油地质特征及勘探方向

准噶尔盆地东南柴窝堡凹陷自晚石炭世以来经历了4个发展演化阶段,形成了多层烃源岩层、储集岩层和盖层。上二叠统芦草沟组、红雁池组为主力烃源岩层和主要勘探目的层,上三叠统-侏罗系为区域性盖层;主力烃源岩层在凹陷北部较南部发育,但其成熟度北部较南部低;主力烃源岩层于三叠纪末期进入生油门限,侏罗纪末期达生油高峰期,与西部及北部圈闭的形成期相匹配。该凹陷三葛庄凸起及北部深大断裂带附近是油气勘探的主要方向。

东濮凹陷异常高压油气藏形成机理

研究了东濮凹陷异常高压油气藏的特征后指出,东濮凹陷内的异常高压可分为烃源岩层异常高压和储集层异常高压。导致烃源岩层异常高压的主要原因是晚期生烃作用;造成储集层异常高压的主要原因是的盐岩或致密泥岩的有效封堵作用、油气充满度及油气成熟度。二次生烃是造成深层异常高压油气藏晚期成藏的原因,具有成藏形成时间晚,运移距离短,气油比高,油气藏压力系数较大,分布在隆起带翼部或构造斜坡带,埋深一般小于4 300 m的特点。

从常规与非常规油气成藏的正相关性角度预测有利区——以孤岛1号凹隆域低部位为例

前人对于如何通过已发现常规油气藏预测未发现非常规油气藏的研究不足。根据常规油气藏与烃源岩层系的非常规油气藏的成藏正相关性,结合凹隆域分布、断层活动性、砂体展布、油气来源及运移路径研究,提出基于相关性油气藏范围的非常规油气藏有利区预测方法。首先,对某一区域从凹隆域岩层的组合构造、烃源岩层系砂体展布、油气来源及运移路径4个方面进行相关性基础研究;然后,将已发现油气藏分布、油气来源研究结果与基础研究结果结合,综合判断相关性油气藏范围;最后,对范围中未发现油气藏的区域进行有利区预测,其中烃源岩发育且存在有利砂岩、砂泥互层、裂缝性泥页岩储层的区域均为有利区。在有利区存在叠置或相邻的烃源岩层系油气藏、有利区紧邻断层且上覆层系发育油气来自断层的油气藏这2种情况下的油气成藏条件最为有利。

长岭断陷龙凤山地区源内致密砂岩气成藏特征

长岭断陷南部龙凤山地区沙二段长期被认为是该区的主力烃源岩层系,近年来在该层段钻井后获得良好的油气显示,表明沙二段的源内致密气具有相当广阔的勘探前景。本文根据钻井、录井等资料,结合古构造分析,详细研究了龙凤山地区沙二段的沉积特征及源储配置关系,进而探讨源内致密砂岩气的成藏特征。分析认为该区发育扇三角洲前缘水下分流河道和席状砂储集体,砂体与暗色泥岩呈互层状,薄层砂岩被暗色泥岩包裹,有利于致密砂岩气藏的形成及保存。

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我国地质工作正经历大变革、大调整,新时代地质工作要更好地支撑服务国家能源资源安全和生态文明建设。在未来很长一段时间内,能源矿产地质调查仍然将作为地质调查工作的重点。在这样一个大的背景下,《沉积与特提斯地质》编辑部与自然资源部沉积盆地与油气资源重点实验室组织出版了本期沉积与油气地质专辑.

Discovery and prediction of high natural gamma sandstones in Chang 73 Submember of Triassic Yanchang Formation in Ordos Basin, China

The large scale development of high natural gamma sandstones has been discovered in the Chang 73 Submember of the Triassic Yanchang Formation in the Ordos Basin, China. High natural gamma sandstones consist of terrigenous detrital rocks with particle sizes ranging from silt to sand. They represent turbidite deposits characterized by high gamma ray values that are more than 180 American Petroleum Institute (API) units on a natural gamma ray log profile. For a long time, very high natural gamma sandstones had been identified as high-quality source rocks, such as oil shales, from conventional well log profiles, such as natural gamma ray well logs. Therefore, predicting the distribution of high natural gamma sandstones was studied. The sedimentary, lithological, and well log characteristics, as well as the genesis of the high radioactivity of high natural gamma sandstones were analyzed in the Chang 73 Submember. Thorium (Th), uranium (U) and other radioactive elements were found, carried by deep hydrothermal activity, and probably resulted in the formation of a relatively high radioactive zone in the cross-section, where high natural gamma sandstones usually develop in large quantities. This caused many turbidite sand bodies, which should have a continuous distribution in the cross-section, to appear to have a discontinuous distribution, when using conventional well log profiles, such as natural gamma ray well logs. From the above mentioned apparent discontinuous distribution of turbidite sand bodies in the cross-section, a continuous distribution can be predicted. It is obvious that the prediction of areas of continuous turbidite sand bodies in the cross-section usually corresponds with areas where high natural gamma sandstones are developed in large quantities. Exploration and development practice demonstrated that the developed method is fast and effective in predicting high natural gamma sandstones in the Chang 73 Submember.

The significance and variation characteristics of interlay water in smectite of hydrocarbon source rocks

To investigate variation characteristics of interlayer water bound up with organic matter in smectite, organo-clay complexes extracted from grinded source rock samples were determined using thermo-XRD, DTA and PY-GC. The dool diffraction peak of organo-clay complexes is postponed from 250 to 550℃ before reaching 1.00 nm and accompanied by exothermal peaks on DTA and organic matter with abundant C20-C30carbon detected by PY-GC, which is different from single smectite and indicates the existence of organic matter in the interlayer of smectite. Water desorption characteristics of organo-clay complexes are in consistent with smectite at 100 and 600℃, but different from smectite at 550℃ with an additional dehydration peak and a remaining d001 diffraction peak, suggesting the vcater removed at 550℃ is interlayer adsorption water rather than constituent water of clay minerals. Comparing the dehydration order and water loss, we conclude that part of interlayer water of smectite may act as the ＂bridge＂ that binds organic matter and smectite, which results in water-expelled lag beyond 250℃ and may provide a good medium for hydrocarbon migration and oil pool formation.

Formation and influencing factors of carbonate source rock of the Lower Permian Chihsia Formation in Chaohu region, Anhui Province

Highly-mature carbonate source rock is essential to the exploration of oil and gas in southern China. In this study, the carbonate strata in the relatively well-developed Lower Permian Chihsia Formation (located in Chaohu, Lower Yangtze) were targeted, and the formation and influencing factors of source rock were discussed based on paleoenvironment reconstruction using comprehensive sedimentology, palynofacies, and organic geochemistry data. The results demonstrate that the Chihsia Formation is oxygen-deficient biogenic carbonate sediments, with marked variations in the organic and inorganic components, formed during a period of Permian transgression. The formation of source rock is the combined result of high bioproductivity and oxygen-deficient environment generated by transgression and oxygenation events which frequently occurred during transgression periods. Source rock was affected by self-dilution effects and diagenesis, causing its heterogeneous distribution in many intervals. Source rock is over 40 m thick, and can be identified based on its different organic, biological, and mineral composition characteristics. The carbonate rock appears to require no specific clay content in order to become a source rock. The combination of sedimentology, palynofacies, and organic geochemistry has provided an effective means for evaluating and predicting high-maturity carbonate source rock in the region.

Potential petroleum sources and exploration directions around the Manjar Sag in the Tarim Basin

Since the discovery of the Tahe oilfield, it has been controversial on whether the main source rock is in the Cambrian or Middle-Upper Ordovician strata. In this paper, it is assumed that the crude oil from the Wells YM 2 and TD 2 was derived from the Middle-Upper Ordovician and Cambrian source rocks, respectively. We analyzed the biomarkers of the crude oil, asphalt-adsorbed hydrocarbon and saturated hydrocarbon in bitumen inclusions from the Lunnan and Hade areas in the North Uplift of the Tarim Basin. Results show that the ratios of tricyclic terpane C2~/C23 in the crude oil, asphalt-adsorbed hydrocarbon and saturated hydrocarbon in bitumen inclusions are less than 1.0, indicating that they might be from Upper Ordovician source rocks; the ratios of C28/（C27＋C28＋C29） steranes in the saturated hydrocarbon from reservoir bitumen and bitumen inclusions are higher than 25, suggesting that they might come from the Cambrian source rocks, however, the ratios of C28/（C27＋C28＋C29） steranes in oil from the North Uplift are less than 25, suggesting that they might be sourced from the Upper Ordovician source rocks. These findings demonstrate that the sources of crude oil in the Tarim Basin are complicated. The chemical composition and carbon isotopes of Ordovician reservoired oil in the Tarim Basin indicated that the crude oil in the North Uplift （including the Tahe oilfield） and Tazhong Depression was within mixture areas of crude oil from the Wells YM 2 and TD 2 as the end members of the Cambrian and Middle-Upper Ordovician sourced oils, respectively. This observation suggests that the crude oil in the Ordovician strata is a mixture of oils from the Cambrian and Ordovician source rocks, with increasing contribution from the Cambrian source rocks from the southern slope of the North Uplift to northern slope of the Central Uplift of the Tarim Basin. Considering the lithology and sedimentary facies data, the spatial distribution of the Cambrian, Middle-Lower Ordovician and Upper Ordovician source rocks was reconstructed on the basis of seismic reflection characteristics, and high-quality source rocks were revealed to be mainly located in the slope belt of the basin and were longitudinally developed over the maximum flooding surface during the progressive-regressive cycle. Affected by the transformation of the tectonic framework in the basin, the overlays of source rocks in different regions are different and the distribution of oil and gas was determined by the initial basin sedimentary structure and later reformation process. The northern slope of the Central Uplift-Shuntuo-Gucheng areas would be a recent important target for oil and gas exploration, since they have been near the slope area for a long time.