准噶尔盆地深层相对优质储层发育机理——淋滤与溶蚀作用

准噶尔盆地腹部侏罗系砂岩埋藏深(>5800m),深部是否发育相对优质储层是制约深层勘探的科学问题.采用镜下观察、测井、试验测试等手段研究了准噶尔盆地深层砂岩的成岩机制和优质储层的发育机理.研究结果表明:(1)准噶尔盆地深层侏罗系砂岩为晚期超压,砂岩粒度细,以粉砂岩和细砂岩为主,岩屑含量高达69%,成分成熟度低,颗粒包壳对砂岩的孔隙度保存有利,但会堵塞喉道,降低渗透率,而且早期充注的油气中的有机酸会溶蚀砂岩地层中的长石和岩屑等矿物,造成高岭石和石英沉淀,对储层的发育与保存不大有利;(2)盆地腹部深层侏罗系西山窑组顶部砂岩中存在一个次生孔隙发育带,孔隙度和渗透率增大,孔隙度从7%增大至11%,渗透率从0.5md增加至2.5md.这个次生孔隙发育带位于侏罗系与白垩系之间的不整合面(埋深5 850m)之下的半风化砂岩中,主要是表生期大气淡水的淋滤作用和深埋后溶蚀作用形成.      

济阳坳陷沾化凹陷陡坡带始新统沙三段扇三角洲储层成岩作用与有利储层成因

15口井岩芯和众多储层实验资料研究表明,沾化凹陷北部陡坡带始新统沙河街组扇三角洲砂体由长石砂岩、岩屑长石砂岩等构成。在埋藏成岩演化过程中,该砂岩储层经历了多种成岩作用,现储层埋深1800~4000m,处于中成岩演化阶段,总体形成了中孔中渗储层(平均孔隙度为19.7%,平均渗透率为111.5×10-3μm2)。但在成岩演化过程中,溶蚀作用对于改善储层质量起到了重要作用,主要在2800~3300m深度段,有机酸对长石颗粒的溶蚀,形成的粒间和粒内孔隙不仅增加了孔隙度,而且提高了储层渗透率,改善了储层质量(孔隙度可达到30%,渗透率达到1000×10-3μm2)。可以看出,确定次生孔隙发育深度段有利于有利储层和油气富集层段预测。     

颗粒包膜在深埋藏砂岩储层原生孔隙保存中的意义

埋藏条件下颗粒包膜对原生孔隙的保存机制是深埋藏砂岩储层原生孔隙演化的关键机制,但不同类型颗粒包膜的成因机制及其在深埋藏砂岩储层原生孔隙保存中的意义颇具争议。本文系统介绍了自生绿泥石包膜、微晶石英包膜和其它类型颗粒包膜的基本特征、成因机制及其对深埋藏砂岩储层质量的影响。目前,自生绿泥石包膜和微晶石英包膜对深埋藏砂岩储层原生孔隙的良好保存作用已经越来越被接受和认同,但自生伊利石、混层粘土、沥青和蛋白石等其它碎屑颗粒包膜的原生孔隙保存作用仍缺乏足够的说服力。对不同类型颗粒包膜本质的模糊认识是当前开展深入研究的现实瓶颈,尤其需要加深对深埋藏储层砂岩原生孔隙保存过程中颗粒包膜形成和演化的理解,以提高油气勘探中钻前储层质量预测的准确性。     

障壁坝砂体储层特征与成岩孔隙定量演化模式 ——以鄂尔多斯盆地延长探区本溪组为例

为明确海陆变迁背景下障壁坝砂体成岩孔隙演化规律,运用岩石薄片、扫描电镜及配套能谱、阴极发光等资料,对延长探区石炭系本溪组障壁成因砂体储集特征与成岩作用进行综合分析,并结合砂岩初始孔隙度恢复模型与薄片孔隙定量分析技术,开展基于埋藏热演化历程的储层孔隙演化参数定量评价,建立该区本溪组障壁坝砂岩孔隙定量演化模式。结果表明:储层砂岩以石英砂岩、岩屑质石英砂岩及岩屑砂岩为主;孔隙度、渗透率平均值分别为4.72%和1.22×10^(-3 )μm^2;储集空间以溶蚀扩大孔、粒内孔、晶间孔为主;现今储层主体已达到晚成岩阶段;砂岩初始孔隙度平均值为38.1%,埋藏至今共经历了四个典型的成岩增/减孔阶段,即P_1～T_2(285～208 Ma)"低地温、快埋藏"的大幅减孔阶段(-30.7%)、T_2～J_3(208～153 Ma)"高地温、缓沉降"的溶蚀增孔阶段(+3.9%)、J_3～K_1(153～96 Ma)"高地温、稳埋深"的减孔定型阶段(-6.6%)、K_1至今(96 Ma～)"低地温、晚隆升"的弱改造阶段。     

海塔盆地优质储层发育特征及控制因素分析

凝灰质砂岩是海塔盆地主要油气储集岩层,凝灰质含量随地层变老而增多,储层物性非均质性强,大量薄片等储层微观分析结果表明,凝灰质砂岩成分和结构成熟度较低,储层储集空间主要为溶蚀成因的次生孔隙,且次生孔隙比例随地层变老而增加.本文提出孔隙成因法,并根据该方法确定凝灰质砂岩优质储层物性下限的孔隙度为10％,渗透率为0.1×10...     

砂岩机械压实与物性演化成岩模拟实验初探

为了模拟沉积地层埋藏成岩过程中,压实作用下储层物性参数的连续变化特征,采用自行设计的成岩作用模拟实验系统,利用不同的现代沉积物样品,开展了砂岩机械压实作用模拟实验。实验表明：砂岩机械压实作用过程中孔隙度和渗透率随深度的变化具有分段性,即早期速变阶段和晚期缓变阶段。利用缓变阶段的数据分析发现,深度与孔隙度之间存在着良好的指数关系,深度与渗透率之间存在着良好的乘幂关系,孔隙度与渗透率之间存在着良好的指数关系。只经历机械压实作用的情况下,相同物源、相同分选的砂岩,颗粒粒度越粗,压实作用过程中,压实减孔率越小,最终保存的孔隙越多,砂岩渗透性越好;不同分选、相近粒度的砂岩,分选越差,压实作用过程中,压实减孔率越大,最终保存的孔隙越少,砂岩渗透性越差。不同岩相类型的砂岩,在压实缓变阶段,分选好中砂岩相平均百米减孔量最小,其次为分选好细砂岩相和分选好粉砂岩相,再次为分选中等粗砂岩相,分选差含砂砾岩相平均百米减孔量最大。     

鄂尔多斯盆地华庆地区长6_3储层成藏期孔隙度定量演化及致密成因机理

基于鄂尔多斯盆地华庆地区长6_3致密砂岩储层三角洲前缘及半深湖相的稳定沉积特征,按照碎屑岩成岩演化特征或地质综合效应建立与孔隙度对应的模拟方程。采用铸体薄片及扫描电镜描述岩石的矿物组分及孔隙类型;图像粒度获取碎屑颗粒的结构特征及分选性;利用沉积微相、测井、样品取样点常规物性及深度分析获取沉积环境、埋藏深度、物性;结合古温度、镜质组反射率、最高热解温度、粘土矿物等数据,开展成岩作用、孔隙演化、相对高渗成因的研究;结合研究区埋藏史、古地温研究,基于不同成岩作用下孔隙度演化特征分析华庆油田长6_3储层致密成因机理。目的层主要属于压实型成岩改造类型,差异性成岩演化过程是导致储层物性不同和孔隙结构差异的根本原因。     

苏北盆地金湖凹陷古近系戴南组孔隙演化及次生孔隙成因分析

金湖凹陷戴南组储层总体为一套中低孔-中低渗碎屑储层,次生孔隙是本区最有效、最重要的孔隙类型,而搞清次生孔隙的分布规律及其成因成为下一步有利储层预测的关键。文中综合利用岩心、普通薄片、铸体薄片、扫描电镜及物性参数等资料,对戴南组储层的岩石类型、物性特征、孔隙类型及次生孔隙分布规律进行了综合分析,并从溶蚀作用的发育条件入手探讨了次生孔隙的成因,以期为下一步有利储层预测和勘探开发提供科学依据。研究认为,金湖凹陷戴南组碎屑岩储层主要发育于三角洲、扇三角洲和滨浅湖,受沉积相带控制,储层类型复杂,以不等粒砂岩、含砾不等粒砂岩、细砂岩及粉砂岩为主,不同地区岩性存在差异。根据岩性三角图,砂岩类型以长石岩屑质石英砂岩为主。砂岩成分成熟度中等偏低,结构成熟度中等。戴南组砂岩孔隙度峰值分布在12.0%~14.0%,渗透率峰值分布在1~10 mD。不同沉积环境和地区储层物性也存在一定差异。三角洲前缘亚相的储层物性最好,平均孔隙度约19.4%,平均渗透率约134.2 mD,岩性以细砂岩为主,主要分布于研究区西部和中部。扇三角洲物性次之,平均孔隙度约12.5%,平均渗透率约6.2 mD,岩性以含砾不等粒砂岩为主,位于桐城断裂带东南部便1井附近。滨浅湖亚相的储层物性最差,岩性以粉砂岩为主,平均孔隙度约8.3%,平均渗透率约2.3 mD。戴南组储层孔隙分为原生孔隙和次生孔隙两大类,以次生粒间溶蚀孔隙为主。溶蚀孔隙包括粒间溶孔、粒内溶孔和铸模孔。粒间溶孔多由粒间碳酸盐胶结物如方解石、白云石、铁方解石等溶蚀后形成,粒内溶孔主要是长石及碳酸盐岩屑被选择性溶解而形成,可见白云石晶粒溶解留下的铸模孔。戴南组储层中的原生孔隙相对较少,主要以石英次生加大后的残余粒间孔的形式存在,发育于埋藏较浅的井如新庄1井、关1-1井。戴南组储层孔隙经历了由原生到次生的演化过程。总体上,在浅于约1 100 m,储层主要处于早成岩A阶段,以原生孔隙为主。在1 100~1 500 m,储层处于早成岩B阶段,形成混合孔隙段。超过1 500 m,储层进入中成岩A阶段,原生孔隙消失殆尽,基本上以次生孔隙为主。戴南组储层存在3个次生孔隙发育带:第一次生孔隙发育带在1 200~1 600 m,分布于埋藏相对较浅-中等的井区;第二次生孔隙发育带分布在1 800~2 800 m;第三次生孔隙发育带在2 900~3 000 m左右。第一、二次生孔隙发育带次生孔隙的绝对值较大,说明溶蚀作用较强。戴南组储层次生孔隙发育与方解石、白云石胶结物的溶蚀及长石碎屑和碳酸盐岩岩屑的溶蚀有关。烃源岩成熟排烃是次生孔隙发育的主控因素;碳酸盐胶结物发育提供了次生孔隙发育的物质基础;长石的溶蚀对次生孔隙发育有一定的贡献;次生孔隙的形成与黏土矿物的相互转化有一定的关系;断裂活动进一步促使了次生孔隙的发育。     

一种改进的通过压汞来计算致密砂岩渗透率经验方法:以鄂尔多斯盆地姬塬地区长7致密砂岩为例

利用Winland公式可以从压汞测试数据中快速合理地预测渗透率,但对于致密砂岩油藏,由于滑脱效应的存在,常规方法测得的地层样品渗透率和实际有一定差距,克氏渗透率能更真实地反映致密砂岩储层的实际情况。利用压汞曲线中孔隙半径的几何加权平均值(RWGM)预测了鄂尔多斯盆地姬塬地区长7致密砂岩地层渗透率:通过鄂尔多斯盆地长7致密砂岩样品的孔隙度、克氏渗透率和进汞曲线的测试数据,利用多元线性回归分析,得到研究区克氏渗透率、孔隙度和RWGM之间的经验公式。相比于Winland公式,RWGM公式在致密砂岩储层中可以更好地预测渗透率,对致密砂岩的开发有重要作用。     

围压和孔隙结构对不同粒级砂岩孔隙度渗透率的影响实验研究

孔隙度和渗透率是储层评价的两个重要参数.岩石毛管压力曲线和核磁共振T2谱图是描述储层微观结构特征的重要参数.通过测量不同压力条件下岩心样品的孔隙度和渗透率,得到了孔隙度和渗透率随压力的变化情况.实验结果表明：孔隙度和渗透率随着压力的增加而降低,并且与压力服从对数函数变化规律.不同孔隙度渗透率区间的砂岩样品,孔隙度和渗透率随着压力变化的趋势不同.通过测量不同粒级砂岩样品的毛管压力曲线和核磁共振T2谱图,证实了孔隙结构对孔隙度和渗透率的影响,微观孔隙结构是决定渗透性好坏的关键因素.     

The terrestrial fauna of the Late Triassic Pant-y-ffynnon Quarry fissures,South Wales,UK and a new species of Clevosaurus (Lepidosauria: Rhynchocephalia)

Pant-y-ffynnon Quarry in South Wales yielded a rich cache of fossils in the early 1950s, including articulated specimens of new species (the small sauropodomorph dinosaur Pantydraco caducus and the crocodylomorph Terrestrisuchus gracilis), but no substantial study of the wider fauna of the Pant-y-ffynnon fissure systems has been published. Here, our overview of existing specimens, a few described but mostly undescribed, as well as freshly processed material, provides a comprehensive picture of the Pant-y-ffynnon palaeo-island of the Late Triassic. This was an island with a relatively impoverished fauna dominated by small clevosaurs (rhynchocephalians), including a new species, Clevosaurus cambrica, described here from a partially articulated specimen and isolated bones. The new species has a dental morphology that is intermediate between the Late Triassic Clevosaurus hudsoni, from Cromhall Quarry to the east, and the younger C. convallis from Pant Quarry to the west, suggesting adaptive radiation of clevosaurs in the palaeo-archipelago. The larger reptiles on the palaeo-island do not exceed 1.5?m in length, including a small carnivorous crocodylomorph, Terrestrisuchus, and a possible example of insular dwarfism in the basal dinosaur Pantydraco.     

Définition d'une limite multicritère ; stratigraphie du passage Campanien–Maastrichtien du site géologique de Tercis (Landes,SW France)Definition of a multi-criteria boundary; stratigraphy of the Campanian–Maastrichtian interval of the geological site at Tercis (Landes,SW France)

Lithostratigraphy, physicochemical stratigraphy, biostratigraphy, and geochronology of the 77–70 Ma old series bracketing the Campanian–Maastrichtian boundary have been investigated by 70 experts. For the first time, direct relationships between macro- and microfossils have been established, as well as direct and indirect relationships between chemo-physical and biostratigraphical tools. A combination of criteria for selecting the boundary level, duration estimates, uncertainties on durations and on the location of biohorizons have been considered; new chronostratigraphic units are proposed. The geological site at Tercis is accepted by the Commission on Stratigraphy as the international reference for the stratigraphy of the studied interval. To cite this article: G.S. Odin, C. R. Geoscience 334 (2002) 409–414.     

The effect of water on accessory phase solubility in subaluminous and peralkaline granitic melts

The solubilities of columbite, tantalite, wolframite, rutile, zircon and hafnon were determined as a function of the water contents in peralkaline and subaluminous granite melts. All experiments were conducted at 1035 °C and 2 kbar and the water contents of the melts ranged from nominally dry to approximately 6 wt.% H₂O. Accessory phase solubilities are not affected by the water content of the peralkaline melt. By contrast, solubilities are affected by the water content of the subaluminous melt, where the solubilities of all the accessory phases examined increase with the water content of the melt, up to 2 wt.% H₂O. At higher water contents, solubilities are nearly constant. It can be concluded that water is not an important control of accessory phase solubility, although the water content will affect diffusivities of components in the melt, thus whether or not accessory phases will be present as restite material. The solubility behaviour in the subaluminous and peralkaline melts supports previous spectroscopic studies, which have observed differences in the coordination of high field strength elements in dry vs. wet subaluminous granitic glasses, but not for peralkaline granitic glasses. Lastly, the fact that wolframite solubility increases with increasing water content in the subaluminous melt suggests that tungsten dissolved as a hexavalent species.     

Quaternary stresses revealed by calcite twinning inversion: insights from observations in the Savonnières underground quarry (eastern France)

Calcite samples were extracted both from the rock matrix and the superficial coating of a karstified fault plane of an underground quarry, located in the eastern border of the Paris basin. The karstification is dated as Quaternary. Analysis of mechanical calcite twinning reveals that only the calcite matrix has also undergone a compression trending WNW that can be attributed to the Mio-Pliocene alpine collision. Both coating and matrix have undergone a strike-slip regime with σ₁ roughly trending north–south, that could correspond to the regional present-day state of stress, a strike-slip compression rather trending NNW, modified by local phenomena. To cite this article: M. Rocher et al., C. R. Geoscience 335 (2003).     

NONMETALS DEPOSITS

正20141520 Bo Ying(Key Laboratory of Metallogeny and Mineral Assessment,MLR,Beijing 100037,China);Liu Chenglin Saline Spring Hydrochemical Characteristics and Indicators for Potassium Exploration in Southwestern and Northern Tarim Basin,Xinjiang(Acta Geoscientica Sinica,ISSN1006-3021,CN11-3474/P,34(5),2013,p.594-602,5 illus.,3 tables,28 refs.)     

MATHEMATICAL GEOLOGY

正20141243Chen Ge(Hangzhou Research Institute of Petroleum Geology,PetroChina,Hangzhou 310023,China);Si Chunsong Study on Sedimentary Numerical Simulation Method of Fan Delta Sand Body(Journal of Geology,     

PROSPECTING EXPLORATION

正20142599Chen Sanming(Guangxi Key Laboratory of Concealed Deposits Exploration,Guilin University of Technology,Guilin541004,China);He Yuzhou Block Model and Reserves Estimation of Panzhihua Iron Deposit Based on 3D Geological Modeling(Journal of Guilin University of Technology,ISSN1674-9057,CN45-1375/N,33(4),2013,p.610-615,9illus.,1table,15refs.)     

STRUCTURAL GEOLOGY

正20140594 Bai Daoyuan(Hunan Institute of Geology Survey,Changsha 410016,China);Zhong Xiang Faults in the Jingzhou Basin and Their Tectonic Settings(Geotectonica et Metallogenia,ISSN1001-1552,CN44-1595/P,37(2),2013,p.173-183,6illus.,59refs.)Key words:basin evolution,tectonic setting,South China In the Upper Paleozoic and Jurassic se-     

STRUCTURAL GEOLOGY

正20141912Cao Hui(State Key Laboratory for Continental Tectonics and Dynamics,Institute of Geology,Chinese Academy of Geological Sciences,Beijing 100037,China)Gravitational Collapse and Folding during Orogenesis:A Comparative Study of FIA Trends and Fold Axial Plane Traces(Geology in China,ISSN1000-3657,CN11-1167/P,40(6),2013,p.1818-1828,9illus.,35refs.,with