碳酸盐矿物的阴极发光性与其Fe,Mn含量的关系

根据不同地区和时代84件碳酸盐样品的阴极发光和Fe,Mn元素分析,在本次研究使用的仪器和实验条件下,方解石和白云石的阴极发光性与其Fe,Mn含量之间存在如下关系:Mn<40μg/g(ppm)时,其阴极发光性主要受Mn的绝对含量控制,当Mn<20μg/g时,不具阴极发光;Fe>5000μg/g时,其阴极发光性与Fe的绝对含关系更为密切,当Fe>10000μg/g时,不具阴极发光;Mn>40μg/g,Fe<5000μg/g时,其阴极发光性受Fe/Mn比值的显著控制,此时当Fe/Mn<7时,具强的阴极发光,30>Fe/Mn>7时,具中等强度的阴极发光,Fe/Mn>30时,具弱的阴极发光。两个热液碳酸岩中单晶白云石样品的阴极发光性和稀土元素含量间的关系说明,碳酸盐矿物的阴极发光性可能还与某些稀土元素的存在有关,它们可能是某些样品具低激活电压和长发光余辉的原因。     

泥盆纪海相碳酸盐岩碳同位素组成及演变

根据对六景泥盆系碳酸盐岩碳同位素组成的系统分析表明：从落霍柯夫期到布拉格期海洋中的δ~１３Ｃ是逐渐变重，埃姆斯期明显变轻．艾菲尔期又开始变重，特别是基维特期有较明显的正向偏移，并继续向上变重，至弗拉斯期与法门期之交达到最大，尔后逐渐变轻，反映了泥盆纪海洋碳同位素组成的演变趋势．这和泥盆纪（二级）海平面的变化趋势是基本一致的，反映海洋碳同位素组成与海平面变化及相关的气候和海洋、大气中ＣＯ_２含量的成因联系。弗拉斯阶－法门阶界线附近δ~１３Ｃ的变化型式表明其间发生的生物绝灭事件是海平面升降和缺氧环境的周期性扩展等因素的累积效应的结果．     

碳酸盐岩米级旋回层序的成因类型及形成机制

在前人研究及自己野外观察的基础上,本文把碳酸盐岩米级旋回层序归为四大类:深水非对称米级旋回层序、L-M米级旋回层序、潮下碳酸盐米级旋回层序、潮坪碳酸盐米级旋回层序。米级旋回层序的形成机制是与米兰柯维奇旋回有关的高频率海平面振荡变化旋回所形成的间断-加积旋回沉积作用,它们的识别标志主要是岩石类型、界面特征、产出环境等。碳酸盐岩米级旋回层序的规则的垂直叠加形式是识别三级旋回层序的基础。     

Cretaceous stratigraphy and palaeoenvironments of the Southern Petén Basin, Guatemala

The Cretaceous deposits of the Southern Petén Basin, an oil-producing province, are located to the south of the Yucatan Platform and to the east of the Chiapas Carbonate Platform of Mexico. The succession in the southern part of this basin has been studied both in wells and at outcrop by microfacies analysis. It is composed of 5000 m of shallow marine carbonates and evaporites with a few thin layers of pelagic limestones rich in organic carbon and planktic foraminifera deposited during peak transgressions or maximum flooding. The sedimentation of this thick succession was not continuous, and the section is punctuated by subaerial erosional bounding surfaces and a single hardground which marks the final drowning of the carbonate platform during the late Maastrichtian. New age determinations have been obtained on the basis of planktic and benthic foraminifera from the Aptian to Santonian Cobán Formation, D, C, B and A Members. Cobán C (Albian) and B (Cenomanian) Members are the present oil reservoirs. The rudist and alveolinid limestones of late Campanian and Maastrichtian age referred to the Campur Formation in the Southern Petén Basin are here reassigned to the Angostura Formation, as recognized in the Chiapas area. The Actela Formation is defined here to encompass the limestone breccia deposits that occur at the Cretaceous–Tertiary boundary and extend into the Parvularugoglobigerina eugubina Zone of early Danian age. The D, C, B and A Members of the Cobán Formation and the Angostura Formation represent second order transgressive and regressive trends in a passive margin area where the deposits indicate a succession of various environments, including fluviatile, salinas, shallow marine carbonate platform, outer shelf and intrashelf basin. High subsidence rates, sea-level changes and tectonic uplift controlled the sedimentation.

Abstract

Les formations crétacées du sud-est du Bassin du Petén, région pétrolière du nord du Guatemala, sont situées au Sud du Yucatan et à l'Est du Chiapas au Mexique. Ces sédiments ont été étudiés à la fois dans deux puits et à l'affleurement par l'analyse des microfaciès. Cet ensemble sédimentaire est composé de 5000 m de carbonates de plate-forme de faible profondeur et d'évaporites, dans lesquels s'intercalent de minces couches de calcaires pélagiques riches en matière organique et en foraminifères planctoniques. Ces calcaires pélagiques se sont déposés lors des maximums de transgressions. La sédimentation de cette épaisse série n'est pas continue et est ponctuée par quelques surfaces d'érosion sub-aérienne et une surface durcie qui souligne l'ennoyage définitif de la plate-forme carbonatée au Maastrichtien terminal. De nouvelles datations ont été obtenues sur la formation Cobán et ses membres D, C, B et A qui s'étagent de l'Aptien au Santonien. Les membres C (albien) et B (cénomanien) constituent les réservoirs productifs. Les calcaires à rudistes et à alveolinidés du Campanien supérieur–Maastrichtien ont été appelés à tort au Petén formation Campur. Ils doivent, selon nous, être attribués à la formation Angostura comme au Chiapas voisin, où affleurent des faciès comparables et de même âge. Une nouvelle formation est créée (formation Actela) pour les brèches calcaires de la limite Crétacé–Tertiaire et de la Zone à Eugubina du Danien inférieur. Les membres D, C, B, A de la formation Cobán et la formation Angostura représentent des cycles transgressifs–régressifs de deuxième ordre. Sur cette marge passive du Petén, les dépôts correspondent à des environnements variés comme des terres émergées soumises à une altération karstique et à des dépôts fluviatiles, des salinas, des plates-formes carbonatées marines, des shelf externes et des bassins intra plate-forme. La sédimentation a été, ici, contrôlée par une forte vitesse de subsidence, les variations du niveau marin et des soulèvements tectoniques.     

Effects of groundwater flow on mineral diagenesis, with emphasis on carbonate aquifers

 This article provides a critical synopsis of the effects of groundwater flow on mineral diagenesis. Emphasis is placed on those aspects and processes that change porosity and permeability in carbonate aquifers, because they are of particular importance to human societies as sources of supplies of water for human consumption (drinking, irrigation) and of crude oil and natural gas. Diagenetic settings in carbonates as well as clastics are generally ill defined. This paper proposes a new comprehensive classification of diagenetic settings into near-surface, shallow-, intermediate-, and deep-burial diagenetic settings; hydrocarbon-contaminated plumes; and fractures. These settings are defined on the basis of mineralogy, petroleum, hydrogeochemistry, and hydrogeology. This classification is applicable to all sedimentary basins. Diagenesis is governed by various intrinsic and extrinsic factors that include thermodynamic and kinetic constraints, as well as microstructural factors that may override the others. These factors govern diagenetic processes, such as dissolution, compaction, recrystallization, replacement, and sulfate–hydrocarbon redox-reactions. Processes such as cementation, dissolution, and dolomitization require significant flow of groundwater driven by an externally imposed hydraulic gradient. Other processes, such as stylolitization and thermochemical sulfate reduction, commonly take place without significant groundwater flow in hydrologically nearly or completely stagnant systems that are geochemically "closed." Two major effects of groundwater flow on mineral diagenesis are enhancement and reduction of porosity and permeability, although groundwater flow can also leave these rock properties essentially unchanged. In extreme cases, an aquifer or hydrocarbon reservoir rock can have highly enhanced porosity and permeability due to extensive mineral dissolution, or it can be plugged up due to extensive mineral precipitation. Received, April 1998 · Revised, July 1998 · Accepted, September 1998     

测井资料在碳酸盐岩洞—裂缝型储层产能评价中的应用

介绍了一种基于测井资料来预测双孔结构碳酸盐岩储层产能的新方法。首先根据碳酸盐岩剖面中双孔结构储层的地质和测井特征,提取与储层产能密切相关的多个测井和地质参数,考虑到这些参数与产能的非线性相关关系以及产能数据的变化特点,采用BP神经网络技术建立其储层产能的预测模型,由此处理了轮南地区的多口井测井资料。所预测的储层段产能与试油产能较为一致,效果良好。     

塔河油田奥陶系碳酸盐岩岩溶发育模式的测井分析

构造运动控制着岩溶发育的期次。塔河油田奥陶系主要发育了加里东中期岩溶和海西早期的两期岩溶。加里东中期岩溶保留于本区南部下奥陶统,岩溶较弱,以发育小的溶孔为特征;海西早期的两期岩溶发育于北部下奥陶统,岩溶较强,以大型溶洞、地下暗河为特征。各期岩溶在纵向上可分为三个带：地表岩溶带、垂直渗沈岩溶带和水平潜流岩溶带。利用各岩溶带自然伽玛测井、井径测井、双侧向电阻率、密度测井、中子孔隙度测井、声波副井和地层檄电阻率成傈测井的响应特征,对两口典型井岩溶带进行划分。以“双峰灰岩”为标准,对两口井的岩海带进行横向对比,建立加里东中期和海西早期岩溶空间分布与发育强度的模式。     

陕西二台子铜金床钠长石碳酸（角砾）岩类特征及形成构造背景分析

从岩石学、矿物学、岩石化学、地球化学、稀土元素等方面研究了二台子铜金矿内长石炭酸（角砾）岩类地质地球化学特征。晚泥盆世－石炭纪,在区域幔羽构造作用下,深部热流体沿先存在构造通道上升进入镇安二台子三级热水沉积盆地之中,形成了石英重晶石炭酸角砾岩、碳酸角砾岩、复成分角砾岩、钠长岩、钠长石碳酸岩,受同性断裂及层位控制明显,并构成了金的矿源层及普遍金矿化。燕山期,具有幔源特征的深部含矿热流体在北东、北西向     

新元古代晚期盖帽碳酸盐岩的成因与“雪球地球”的终结机制

新元古代晚期约635 Ma的地球发育了到达赤道附近的冰川作用，地质记录上表现为代表寒冷气候的冰期沉积杂砾岩，直接被代表温暖环境的碳酸盐岩层（常称盖帽碳酸盐岩）覆盖。由于盖帽碳酸盐岩奇特的岩石学和地球化学特征，引起了对其成因认识的巨大争论，提出了“雪球地球”和“甲烷渗漏”等假说。“雪球地球”假设可以解释一些令人困惑的地学现象，如低纬度和低海拔冰川沉积、盖帽碳酸盐岩、碳酸盐δ13C负漂移和条带状铁矿层等，但许多科学家对此提出了质疑。最近对盖帽碳酸盐岩的δ13C分析结果（最低达-41‰）、盖帽碳酸盐岩发育的类似现代冷泉碳酸盐岩沉积组构等似乎支持“甲烷渗漏”假说。     

Lithological and physical properties of core samples from the Sagara oil field: Oil occurrence in Sagara core samples

Abstract   A drilling and coring investigation of the Sagara oil field, central Honshu, Japan, was conducted to contribute to the understanding of hydrocarbon migration processes in a forearc basin. Core samples were analyzed to determine lithology, physical properties (specifically gas permeability) and the characteristics of oil occurrence. Gas permeability values greater than approximately 10⁻¹¹ m² constitute the basic precondition for any lithology to serve as a potential fluid conduit or reservoir in the Sagara oil field. Cores recovered from the 200.6-m-deep borehole were primarily composed of alternating siltstone, sandstone and conglomerate, all of which are correlated to the late Miocene Sagara Group. Both sandstone and conglomerate can be classified into two types, carbonate-cemented and poorly to non-cemented, based on matrix material characteristics. Oil stains are generally absent in the former lithology and more common in the latter. Variations in physical properties with respect to gas permeability values are directly related to the presence and character of carbonate cement, with higher permeabilities common in poorly to non-cemented rocks. The relationships between lithology, oil-staining, cementation and permeability indicate that cementation preceded oil infiltration and that cementation processes exerted significant control on the evolution of the reservoir.