Reconstruction of the Upper Cretaceous chalks removed by dissolution during the Cenozoic in the western Paris Basin

 During the Cenozoic, in the western Paris Basin, atmospheric weathering of the chalks with flints of the Upper Cretaceous led to the creation of clay with flints. A reconstitution of the chalks lost to dissolution is proposed and is based on the determination of the age of the parent chalks of the clay with flints and the quantification of the thickness of dissolved chalk. The chalks affected by weathering range in age from Turonian to Maastrichtian, thus confirming the deposition of calcareous sediments in the western Paris Basin up to the Maastrichtian. Chalk weathering took place in situ, as indicated by the preservation of the stratigraphic succession of the chalk in the clay with flints profiles. Weathering led to the dissolution of 20–200 m of chalk, with regional variations. The weathering rate varies between 2.1 and 14.5 m/Ma. Received: 20 July 1998 / Accepted: 1 July 1999     

柴达木盆地石油地质条件、资源潜力 及勘探方向

通过对柴达木盆地石油地质条件的分析,总结建立了富烃凹陷古构造成藏、源外古隆起-古斜坡成藏、源上晚期构造成藏以及富烃凹陷周缘斜坡致密油-岩性成藏等4类石油成藏模式,优选类比法和成因法客观评价了盆地不同区带、不同区块、不同层系的常规油及致密油资源,得出常规油地质资源量为29.59×10~8 t,致密油资源量为8.58×10~8 t。结合盆地石油勘探现状,理清了剩余常规石油地质资源及其分布,明确柴西地区为剩余常规石油地质资源最丰富、资源丰度最大的地区。指出盆缘古隆起及斜坡区、盆内凹陷-斜坡区、盆内大型晚期构造带是近期重点勘探领域:狮子沟—大乌斯构造带、油泉子—开特米里克构造带、阿尔金山前西段是常规石油有利勘探目标,柴西南区的跃东—扎哈泉—乌南和红柳泉—跃进一带,以及柴西北区的小梁山—南翼山等地区是致密油勘探现实有利区。     

准噶尔盆地石油地质条件、资源潜力及勘探方向

近年来,准噶尔盆地的油气勘探在许多新领域取得重大突破,展现良好勘探前景。然而,盆地第三次油气资源评价结果与勘探实际、储量增长之间的矛盾越来越突出,常规、非常规领域的石油资源潜力亟待落实。在解剖盆地石油成藏条件,分析成藏控制因素,总结不同地区、不同层系成藏模式及其富集规律的基础上,开展地质评价参数研究,优选评价方法,重新评价盆地资源潜力,梳理了盆地有利的勘探方向。评价结果显示:盆地常规、非常规石油资源量近100×10~8t,综合探明率约为27%;剩余待探明石油资源量近55×10~8 t,主要分布于富烃凹陷斜坡区的二叠系—三叠系、盆地深层及凹陷周缘低勘探程度的凸起构造。未来应围绕盆地这3个领域,加大勘探力度,同时依托技术进步,努力拓展页岩油等资源潜力大、勘探程度低的勘探领域。     

Residence time of Chalk groundwaters in the Paris Basin and the North German Basin: a geochemical approach

The comparative geochemical and isotopic study of confined and unconfined Chalk groundwaters of the Paris Basin and the N German Basin proves a significant chemical evolution during groundwater flow from the recharge zones to the deep confined aquifer. Different time dependent geochemical parameters have been tested as dating tools: Cation ratios (Sr²⁺/Ca²⁺, Mg²⁺/Ca²⁺), N–NO⁻₃, noble gas contents as paleotemperature indicators (Ne, Ar, Kr, Xe), radiogenic He, ¹³C, ¹⁴C, ¹⁸O, ²H, ³H. Cation ratios and ¹³C show the importance of incongruent dissolution processes in the Chalk aquifer. Water–rock interactions were taken into account in a multi-step dissolution model to determine radiocarbon groundwater ages. The oldest waters in the confined part of the Paris basin Chalk with maximum ¹⁴C ages of 14,000 a B.P. contain pleistocene recharge components as can be shown by a stable isotope depletion and noble gas temperatures significantly lower than in recent groundwaters. Chalk waters at the Lägerdorf site in Northern Germany show a distinct stratification with respect to residence times and hydrochemistry.     

The Vigny limestones: a record of Palaeocene (Danian) tectonic-sedimentary events in the Paris Basin

Danian marine sedimentation in the Paris Basin occurred between two major erosional phases. The earlier was responsible for the stripping of presumably deposited Maastrichtian sediments and of a variable thickness of Campanian chalk. The later occurred during the late Palaeocene and resulted in the erosion of almost all Danian deposits, which are now limited to small and scattered outcrops. One of these outcrops corresponds to reefal and peri‐reefal limestones of middle to late Danian age, exposed in the quarries of Vigny (NW of Paris). Danian deposits here show intricate relations with the surrounding Campanian chalk. Danian sedimentation was contemporaneous with faulting, which generated signifiant sea‐floor relief and resulted in contrasting depositional areas: topographic highs with coralgal reefs, and depressions where calcirudite channel fill accumulated. Normal faulting occurred along WNW–ESE master faults. The generation of submarine fault scarps gave rise to various types of gravity‐driven phenomena, including the sliding and slumping of large blocks of reefal limestone and the deposition of carbonate debris flows. Along with the redeposition of the Danian carbonates, flows of fluidized and reworked Campanian chalk resulted from the peculiar physical properties of the undercompacted chalks. Erosion and faulting occurred predominantly during the Palaeocene and represent a major episode in the physiographic evolution of the Paris Basin.     

鄂尔多斯盆地中生界石油地质条件、资源潜力及勘探方向

鄂尔多斯盆地中生界油气资源丰富,三叠系延长组和侏罗系延安组是主力含油层系。在鄂尔多斯盆地石油地质条件研究的基础上,提出沉积相、输导体系、异常压力和构造为中生界成藏的主要控制因素,建立了三叠系延长组大型岩性油藏模式和侏罗系古地貌控藏模式,并结合盆地勘探成果,精细评价了鄂尔多斯盆地石油地质资源量,预测了油气资源的空间分布。结果表明:鄂尔多斯盆地石油地质资源量约为146.50×10~8 t,其中常规油资源量为116.50×10~8 t,致密油资源量为30.00×10~8 t;按层系分,三叠系石油资源量为137.20×10~8 t,侏罗系石油资源量为9.30×10~8 t。盆地剩余资源量为96.93×10~8 t,姬塬、陇东和志靖—安塞等地区,是长庆油田的规模储量区,仍然是未来勘探的主要区域。延长组长6、长8油层组和侏罗系是下一步勘探的重点层系;延长组下部的长9、长10油层组为新的目标层系;长7油层组致密油具有较大的勘探潜力。     

The role of geodiversity on the groundwater resource potential in the upper Blue Nile River Basin, Ethiopia

Groundwater has been the main source of water supply for large cities and towns over the last few decades in the upper Blue Nile River Basin, Ethiopia. However, provision is often unsuccessful because of poor well productivity, difficult drilling conditions, poor well positioning, or sometimes due to poor water quality. The growing pressure of urban population and industrial development is focusing unprecedented attention on the groundwater potential of the basin. The purpose of this work is to spatially characterize the groundwater potential of the upper Blue Nile River Basin with respect to variable recharge and geodiversity. The study shows that from the annual recharge obtained using the base flow separation method, the renewable groundwater potential in the basin was estimated to be in the range of 1.2 and 2 billion m³/year. The aquifers in the area are divided into three categories: low to moderate productivity (≈3.5 l/s) which includes crystalline basement rocks, acidic lava flows and domes, and very fine alluvial sediments; moderate to high productivity (≈5.5 l/s) that includes Mesozoic sedimentary rocks (sandstone, limestone, gypsum, dolomite); and high to very high productivity (≈20 l/s) which includes basic lava flows of the Trap series, Quaternary lava flows and alluvial sediments.     

松辽盆地西缘断陷盆地特征及油气远景

大杨树盆地与松辽盆地及其他西缘盆地的对比, 发现它们具有类似的充填序列和构造演化历史, 表明这些盆地应是松辽盆地的一部分。目前, 在陆家堡凹陷中已发现具有一定规模的油田, 大杨树盆地深部发现良好的烃源岩, 这表明沿松辽盆地西缘发育的一系列断陷盆地具有良好的油气远景, 大杨树盆地是其中最具勘探潜力的盆地之一。     

塔里木盆地西部巴什托普断裂的主要特征及其油气勘探意义

巴什托普断裂经历了两期变形。早期变形发生在中生代(或中生代末),沿中寒武统膏盐层发生的顺层滑动在上盘形成断层转折褶皱,之后发生冲断并伴有断层传播褶皱发育。由于南天山冲断带向南扩展(始自始新世晚期在中新世达到高潮)时该断裂带不活动,巴楚断隆南界的西段由中生代的巴什托普断裂北移至色力布亚断裂带。晚期变形发生在更新世,向南冲断,属西昆仑前陆褶皱冲断带中低级别的背冲断层。该地的生储盖条件较好,是相对的低应变区,因而是有利的油气勘探区。     

中国中西部前陆盆地烃源岩特征与油气资源潜力分析

中国中西部前陆盆地(冲断带)以发育陆相烃源岩为特征。中西部周缘和弧后前陆盆地烃源岩形成于前陆盆地沉积期,包括准噶尔西北缘、准噶尔南缘、塔里木盆地西南缘、吐哈盆地二叠系烃源岩和川西、鄂尔多斯盆地西缘三叠系烃源岩;再生前陆盆地(冲断带)烃源岩主要形成于再生前陆盆地沉积之前的三叠—侏罗系和白垩系、古近系。根据沉积环境可以将烃源岩分为被动大陆边缘海相、残留海—(泻)湖相、湖沼相、内陆坳陷淡水湖相以及内陆坳陷断陷半咸水-咸水湖相烃源岩5种类型,其中湖沼相煤系烃源岩有机质类型为III型,以产气为主,其他烃源岩有机质类型主要为II型,其次为I型,以产油为特征。中国中西部前陆盆地石油潜在资源量为89.17×108t,天然气潜在资源量为101 464×108m3,与国外典型前陆盆地相比,中国前陆盆地具有富气特征。     

吐哈盆地石油地质条件、资源潜力及勘探方向

通过对吐哈盆地生储盖组合配置、成藏模式等石油地质条件的综合研究,认为吐哈盆地主要发育侏罗系西山窑组、八道湾组煤系烃源岩,以及二叠系桃东沟群湖相烃源岩,这2套烃源岩生油强度较大的地区均位于台北凹陷主体沉降区,具备形成大油田的烃源基础。盆地主要发育侏罗系、三叠系和二叠系等3套储层,侏罗系储层主要为辫状河三角洲分流河道粗砂岩,二叠系梧桐沟组、三叠系克拉玛依组储层主要为扇三角洲、辫状河三角洲前缘水下分流河道的细砂岩、砂砾岩。侏罗系主要有正向分异、逆向分异、垂向分异及混合型等4种成藏模式;二叠系为侧向长距离运聚-古斜坡成藏模式;三叠系为源内垂向运聚-自生自储油气成藏模式。采用类比法、统计法、成因法及特尔菲加权法综合得到吐哈盆地常规石油地质资源量为10.09×10~8t,剩余资源量为6.07×10~8t。通过地质评价、原油剩余资源量和剩余资源丰度的分布预测,提出了鄯善弧形带、鲁克沁—红连带、西部弧形带3个勘探方向及有利目标区。     

太原盆地岩溶地热系统的形成演化及其地热资源潜力

【研究目的】太原盆地作为优质岩溶热储分布与城市供暖需求匹配良好的地区之一,其岩溶地热系统的形成演化与成因要素的研究对本区地热资源的整体开发以及断陷盆地型地热资源展布规律的认识均具有重要的指导意义。【研究方法】本文在综合前人研究成果与最新54口地热井资料的基础上,分析了太原盆地岩溶地热系统的热源、热储展布和水热动力学特征,并分8个单元评价了地热资源量。【研究结果】结果表明,岩溶热储发育的层位主要为华北板块广泛分布的下古生界奥陶系,经历了早古生代末的表生岩溶、晚古生代的直接盖层沉积、中生代岩溶地热系统初始形成、新近纪的改造与第四纪最终定型等5个阶段。该地热系统的热源来自于新生代裂谷盆地产生的高大地热流（最高达79.12 mW/m2）,热传递方式可分为强烈对流型（盆地边缘）和热传导型（盆地内部）截然不同的两类。热储储集性能具纵向分层、平面分带特征。在纵向上识别出15～20层有效储集段,累计厚度160～180 m,可划分为3~4层主力含水段;在平面上有利储集带主要受NE向隐伏构造的控制,且主力含水层在运移过程中易发生“越流”现象。盆地中段的奥陶系热储因埋藏适中（约400~1900 m）、且储层温度较高（30~75℃）,是最有利的勘探开发区。依据热储体积法评价出太原盆地岩溶地热系统可利用的静态地热资源量为83.03×108 GJ,折合标煤2.83×108 t。【结论】年开采地热资源量可满足1502万m2的供暖面积。鉴于目前已开发资源仅占可开发的23.3%,开发潜力巨大。创新点：根据区域构造－沉积旋回对地热系统组成要素的控制作用,剖析山间断陷盆地岩溶地热系统的成因模式;结合地热井产水量与测井曲线解释成果,分析热储物性纵向分层、平面分带的规律;采用热储体积法分区块精细评价太原盆地岩溶地热系统的地热资源量。     

青海共和盆地结构构造与能源资源潜力

共和盆地处于西秦岭、南祁连、东昆仑造山带结合部,其中发现了高温干热岩及多套烃源岩,但地热藏和油气藏的成因、资源潜力与分布规律尚不清楚,难以对其开展准确评价和有效勘探开发。本文在系统研究共和盆地及周缘地层发育、沉积充填、构造变形与盆地深部结构的基础上,深入探讨了盆地演化的动力学机制,分析了盆地地热藏和油气藏的成藏主控因素,预测了有利分布区带和勘探方向。多期活动的哇洪山—温泉、多禾茂、瓦里贡、塘格木右行走滑逆冲断裂与青海南山左行走滑逆冲断裂异向、同向相交(切),叠加地幔上涌作用,导致在中新生代共和盆地长期处于走滑-伸展的独特环境,并控制了盆地7个隆起、断陷构造单元的展布及属性。它经历了6期演化阶段：早中三叠世处于昆北弧前盆地及陆缘火山弧带,共和盆地基底主要岩石发育;晚三叠世阿尼玛卿洋闭合并发生碰撞造山,共和盆地褶皱基底形成;晚三叠纪末期发生碰撞后伸展,发育初始小型陆内裂谷盆地;在侏罗纪—白垩纪区域性伸展环境下形成局部断陷盆地;古近纪晚期—中新世发育拉分-断陷盆地;中新世末至今发育陆内前陆盆地。形成了3个大构造-沉积层序和8个亚层序,发育了深海陆棚相-碳酸盐岩台地相-火成岩相以及多旋回的冲积...     

Erosion balance in the watersheds of the western Paris Basin by high-frequency monitoring of discharge and suspended sediment in surface water

An accurate quantification of erosion, based on high-frequency monitoring of river discharge and suspended sediment fluxes is proposed for two watersheds in the western Paris Basin, a sensitive area with respect to erosion phenomena. This continuous monitoring makes it possible to include flood events of short duration, but significant erosion potential. The obtained erosion rate (16 and 21 t?km^?2?yr^?1) is among the weakest of the planet (3.5 to 18?000 t?km^?2?yr^?1). However, this annual balance does not reflect the behaviour of these rivers which can be torrential in certain cases. To cite this article: B. Laignel et al., C. R. Geoscience 338 (2006).     

川中地区公山庙油田侏罗系大安寨段致密油资源潜力分析

公山庙油田侏罗系大安寨段油层孔隙度大多小于2％,渗透率一般小于0.05×10-3μm2,属于典型的致密油层.该油层平面上大面积分布,存在明显的“甜点”区;剖面上非均质性强,顶部大一亚段和底部大三亚段的厚层介壳灰岩为主力产油层,中部大一三亚段的介壳灰岩与页岩薄互层为次要产油层.构造、介壳灰岩及暗色泥岩厚度对致密油富集没有明显的控制作用,“甜点”主要分布在公山庙构造西侧斜坡区.通过对公山庙油田大安寨段沉积演化、烃源岩生烃条件、储层特征及油气分布规律的研究,结合生产井数据,运用容积法和产量递减拟合法分别计算可采资源量,预测公山庙油田大安寨段致密油可采资源量分别为338.11万t和155.74万t.     

Tectonic evolution of the Anadyr Basin,northeastern Eurasia,and its petroleum resource potential

The published data on the sedimentation conditions, structure, and tectonic evolution of the Anadyr Basin in the Mesozoic and Cenozoic are reviewed. These data are re-examined in the context of modern tectonic concepts concerning the evolution of the northwestern Circum-Pacific Belt. The re-examination allows us not only to specify the regional geology and tectonic history, but also to forecast of the petroleum resource potential of the sedimentary cover based on a new concept. The sedimentary cover formation in the Anadyr Basin is inseparably linked with the regional tectonic evolution. The considered portion of the Chukchi Peninsula developed in the Late Mesozoic at the junction of the ocean-type South Anyui Basin, the Asian continental margin, and convergent zones of various ages extending along the Asia-Pacific interface. Strike-slip faulting and pulses of extension dominated in the Cenozoic largely in connection with oroclinal bending of structural elements pertaining to northeastern Eurasia and northwestern North America against the background of accretion of terranes along the zone of convergence with the Pacific oceanic plates. Three main stages are recognized in the formation of the sedimentary cover in the Anadyr Basin. (1) The lower portion of the cover was formed in the Late Cretaceous-Early Eocene under conditions of alternating settings of passive and active continental margins. The Cenomanian-lower Eocene transitional sedimentary complex is located largely in the southern Anadyr Basin (Main River and Lagoonal troughs). (2) In the middle Eocene and Oligocene, sedimentation proceeded against the background of extension and rifting in the northern part of the paleobasin and compression in its southern part. The compression was caused by northward migration of the foredeep in front of the accretionary Koryak Orogen. The maximum thickness of the Eocene-Oligocene sedimentary complex is noted mainly in the southern part of the basin and in the Central and East Anadyr troughs. (3) The middle Miocene resumption of sedimentation was largely related to strike-slip faulting and rifting. In the Miocene to Quaternary, sedimentation was the most intense in the central and northern parts of the Anadyr Basin, as well as in local strike-slip fault-line depressions of the Central Trough. Geological and geophysical data corroborate thrusting in the southern Anadyr Basin. The amplitude of thrusting over the Main River Trough reaches a few tens of kilometers. The vertical thickness of the tectonically screened Paleogene and Neogene rocks in the southern Main River Trough exceeds 10 km. The quantitative forecast of hydrocarbon emigration from Cretaceous and Paleogene source rocks testifies to the disbalance between hydrocarbons emigrated and accumulated in traps of petroleum fields discovered in the Anadyr Basin. The southern portion of the Anadyr Basin is the most promising for the discovery of new petroleum fields in the Upper Cretaceous, Eocene, and Upper Oligocene-Miocene porous and fracture-porous reservoir rocks in subthrust structural and lithological traps.     

洞庭盆地生物气地球化学勘探及资源远景评价

湖南省洞庭盆地具备形成一定规模生物气藏的条件.针对生物气资源勘探,2013~2016年在盆地内开展了以地球化学为主的勘探工作,进行了比较系统的地表沉积物测量.勘探涉及面积2 060 km2,采集样品1 498个,采用现场顶空气游离烃、室内酸解烃和少量微量甲烷同位素指标测试.研究结果表明:①洞庭盆地甲烷地球化学异常由游离烃(顶空气)和吸留烃(酸解烃)组成.游离烃是现存地下生物气的动态反映,酸解烃与沉积相造成的碳酸盐沉积和古河道分布有关.②洞庭盆地为甲烷指标高背景区域,异常分布与第四纪断陷盆地分布基本吻合,尤以沅江凹陷显著.③酸解烃河坝镇异常与中部NE向串珠状和东南部次级局部异常组成的环状异常围绕着沅江凹陷,表明其可能是洞庭盆地潜在生物气烃源区.④沅江凹陷北部青树嘴—河坝镇一带是盆地内游离烃甲烷特高值异常区,是下覆生物成因天然气在浅表层直接渗漏的反映;酸解烃甲烷高值异常环绕着游离烃甲烷高值异常,构成了酸解烃环状异常和游离烃顶端异常最佳油气藏组合模式.青树嘴—河坝镇区块是洞庭盆地下覆生物气的“烟囱”,是本区生物气勘探最有可能突破的地区.     

Evolution of the middle crust beneath the western Pannonian Basin: a xenolith study

Felsic to mafic granulite xenoliths from late Neogene basalt pyroclastics in four localities of the western Pannonian Basin (Beistein, Kapfenstein, Szigliget and Káptalantóti (Sabar-hegy) were studied to find out their metamorphic and fluid history. The characteristic mineral assemblage of the granulites consists of Pl + Opx + Qtz ± Cpx ± Bt ± Grt ± Kfs. Based on abundant magmatic relic microstructural domains occurring in these rocks, the potential precursors might have been predominantly felsic igneous or high to ultrahigh temperature rocks. Ternary feldspar thermometry provides a rough estimate of temperatures of about 920–1070 °C. The first fluid invasion event, which is linked with this early high to ultrahigh temperature stage is characterised by primary pure CO₂ inclusions in apatite and zircon. The densest primary CO₂ inclusions indicate 0.52–0.64 GPa pressure at the estimated temperature range of crystallization. According to mineral equilibria and geothermobarometry, the high to ultrahigh temperature rock cooled and crystallized to granulite of predominantly felsic composition at about 750–870 °C and 0.50–0.75 GPa in the middle crust, between 20 and 29 km depths. The second fluid invasion event is recorded by primary CO₂-rich fluid inclusions hosted in the granulitic mineral assemblage (plagioclase, quartz and orthopyroxene). In addition to CO₂, Raman spectroscopy revealed the presence of minor N₂, H₂S, CO and H₂O in these inclusions. Partial melting of biotite-bearing assemblages could be connected to the next fluid invasion shown by secondary CO₂-rich fluids recorded along with healed fractures in plagioclase, clinopyroxene and orthopyroxene. This event could have happened at depths similar to the previous ones. The final step in the granulite evolution was the sampling in the middle crust and transportation to the surface in form of xenoliths by mafic melt. This event generated temperature increase and pressure decrease and thus, limited melting of the xenoliths. The youngest fluid inclusion generation, observed mostly in healed fractures of felsic minerals, could be associated with this event.     

Meso-Cenozoic geodynamic evolution of the Paris Basin: 3D stratigraphic constraints

3D stratigraphic geometries of the intracratonic Meso-Cenozoic Paris Basin were obtained by sequence stratigraphic correlations of around 1 100 wells (well-logs). The basin records the major tectonic events of the western part of the Eurasian Plate, i.e. opening and closure of the Tethys and opening of the Atlantic. From earlier Triassic to Late Jurassic, the Paris Basin was a broad subsiding area in an extensional framework, with a larger size than the present-day basin. During the Aalenian time, the subsidence pattern changes drastically (early stage of the central Atlantic opening). Further steps of the opening of the Ligurian Tethys (base Hettangian, late Pliensbachian;...) and its evolution into an oceanic domain (passive margin, Callovian) are equally recorded in the tectono-sedimentary history. The Lower Cretaceous was characterized by NE–SW compressive medium wavelength unconformities (late Cimmerian–Jurassic/Cretaceous boundary and intra-Berriasian and late Aptian unconformities) coeval with opening of the Bay of Biscay. These unconformities are contemporaneous with a major decrease of the subsidence rate. After an extensional period of subsidence (Albian to Turonian), NE–SW compression started in late Turonian time with major folding during the Late Cretaceous. The Tertiary was a period of very low subsidence in a compressional framework. The second folding stage occurred from the Lutetian to the Lower Oligocene (N–S compression) partly coeval with the E–W extension of the Oligocene rifts. Further compression occurred in the early Burdigalian and the Late Miocene in response to NE–SW shortening. Overall uplift occurred, with erosion, around the Lower/Middle Pleistocene boundary.