库车凹陷克拉2气田深层优质储层成因及成岩作用模式

基于成岩作用的影响因素及库车盆地的实际,深入研究了克拉2气田次生孔隙发育段储层岩石成分特征及早期古气候条件下胶结物对于成岩作用及次生孔隙的影响,分析了地层压力系统中超高压带、构造裂缝、自生矿物分带的成因、作用、特点及其与储层物性、成岩环境的相关关系,评价了储层中长石、方解石的溶解,白云石对方解石的交代,压实、胶结等主要成岩作用类型对次生孔隙的具体影响和贡献,认为该区早期碱性成岩环境下方解石胶结物的溶解是形成该区次生孔隙发育带的主导因素,并根据该区自生矿物流体包裹体及埋藏史特征,建立了该区成岩作用及孔隙演化的模式。     

塔中Ⅰ号断裂坡折带上奥陶统碳酸盐岩储层微观孔隙成因

塔中Ⅰ号断裂坡折带上奥陶统良里塔格组碳酸盐岩储集空间类型主要有孔、洞、缝三大类,微观储集空间主要有粒内溶孔、铸模孔、粒间溶孔、晶间溶孔和微裂缝。通过对台地边缘16口井的良里塔格组灰岩进行岩石薄片鉴定、胶结物地球化学分析以及成岩演化序列研究,指出微观孔隙主要形成于埋藏成岩环境中,并列出4项具有指示意义的证据,包括：方解石胶结物中高温包裹体普遍存在;方解石胶结物稳定氧碳同位素丰度分异特征;灰岩中丰富与优质储层伴生的指示埋藏成岩作用的白云石;广泛分布的H₂S气体。此外,分析了溶蚀性流体的主要组分和不同区域埋藏溶蚀作用强度的差异性。     

莱州湾凹陷北洼沙三段砂岩碳酸盐胶结物特征及地质意义

碳酸盐胶结特征不仅反映了成岩环境,而且可表明成岩阶段及其对储层质量的影响。综合运用岩石学、矿物学和地球化学等方法,对莱州湾凹陷北洼古近系沙三段砂岩中碳酸盐胶结物的分布规律、形成环境、物质来源、沉淀温度以及其对储层物性的影响进行了系统研究。结果表明：沙三段发育两期碳酸盐胶结物,分别为形成于埋藏早期的菱铁矿和隐晶方解石,以及成岩作用中后期形成的方解石、白云石、铁方解石和铁白云石,其中方解石是最主要的胶结物类型。碳酸盐胶结物形成于埋藏作用中后期的高盐度流体环境,与有机质脱羧作用相关,有机碳是最主要的碳来源,Ca2+是长石的溶蚀和粘土矿物转化的产物。包裹体均一温度研究结果表明,碳酸盐胶结物在油气充注的同时或之后形成。形成于成岩作用早期的碳酸盐胶结物在一定程度上增强了岩石骨架颗粒固结和抗压实能力,同时也是后期有机酸溶蚀的主要对象,对储层物性起到促进作用;溶蚀作用之后形成的碳酸盐胶结物占据粒间孔隙和部分溶蚀孔隙,对储层物性起到破坏作用。     

珠江口盆地东沙隆起珠江组灰岩成岩环境的恢复

本文主要在岩心观察和描述的基础上,借助于薄片分析、扫描电镜分析和阴极发光分析,通过不同成岩组构的识别及其成岩作用特征分析,结合区域地质背景,恢复珠江口盆地东沙隆起珠江组灰岩经历的成岩环境。结果表明:(1)整体的海侵背景和渐进埋藏过程使得珠江组灰岩中不发育表生成岩作用,但是频繁的海平面变化使得古地貌高部位生长的灰岩受到大气淡水的成岩改造,珠江组灰岩主要经历了海水潜流、大气淡水渗流、大气淡水潜流和埋藏环境等成岩环境;(2)不同成岩环境具有明显不同的成岩组构特征。海水潜流环境的成岩组构主要有广泛发育的藻的包壳作用和藻类-生物的相互包裹、生物钻孔的发育、泥晶化作用、海绿石的形成以及等厚纤维状环边胶结物、颗粒表面的刀刃状或叶片状胶结物、犬牙状胶结物和共轴生长方解石胶结物的发育;淡水潜流环境的主要成岩特征包括粒状亮晶方解石胶结物、棘皮多期共轴加大边和有限的溶解作用;淡水渗流环境中识别的成岩特征有非组构选择性溶解作用、示底构造、微型钟乳状胶结物和新月形胶结物;埋藏成岩环境的成岩作用主要包括压实、压溶作用、晚期溶蚀作用以及油气的侵位。     

贵州紫云上石炭统叶状藻礁灰岩胶结物特征

贵州紫云县猴场镇扁平村的上石炭统叶状藻礁及其周边灰岩中广泛发育大量的各类胶结物。通过对胶结物的形态、结构和阴极发光特征以及胶结物间的接触关系的研究,可以确定成岩作用的先后并识别成岩环境。浅海海底同生成岩阶段大的孔隙中形成等厚环边针状胶结物、葡萄状胶结物,小的孔隙里形成微晶胶结物。早成岩阶段形成微亮晶和斑块状亮晶方解石胶结物和放射纤维扇状胶结物,表生成岩阶段的溶蚀作用和胶结作用强烈,胶结物类型有斑块状或等粒的方解石胶结物和等厚环壁柱状胶结物,等厚环壁柱状胶结物在所有胶结物中体积是较大的。早期胶结作用使叶状藻礁灰岩孔隙度大为降低。中、晚成岩阶段,孔隙被等厚环壁刃状胶结物和晶簇或斑块状亮晶方解石所充填,有些先成的胶结物被热液改造。后生作用阶段发生的主要是构造破裂作用,其中少数裂隙被红褐色含Fe2O3微晶层和晶体粉砂及渗流豆粒充填。叶状藻礁灰岩的孔隙在晚成岩阶段前或中被胶结而之后没有创造出大且连通的孔隙,是它没能成为油气储集层的原因之一。     

鄂中地区下奥陶统碳酸盐岩成岩作用及孔隙演化

本文根据岩石学特征、沉积构造、生物化石等标志将鄂中地区下奥陶统碳酸盐岩沉积划分为五种不同的相带，其中以开阔台地相最为发育。并采用阴极发光、氧碳同位素、混合染色等手段，详细研究了该区碳酸盐岩成岩作用类型、成岩序列和孔隙演化特征。认为胶结、溶解、压溶作用和白云石化作用是控制该区碳酸盐岩储层的主要因素，聚集期孔隙形成于深埋藏成岩环境，与压溶作用和深部溶解作用密切相关     

辽河盆地西部凹陷沙河街组砂岩碳酸盐胶结物特征

碳酸盐胶结物中氧碳同位素组成研究是分析成岩过程中流体-岩石相互作用的重要技术方法.综合运用岩石学、矿物学和地球化学方法，对辽河盆地西部凹陷沙河街组砂岩中碳酸盐胶结物的化学组成和碳酸盐胶结物及成岩流体同位素组成特征进行系统分析.研究表明，研究区碳酸盐岩主要为方解石和白云石，胶结物主要类型为嵌晶式胶结、孔隙式胶结、斑块状胶结和星点状胶结.碳、氧稳定同位素组成能有效地反映成岩-成矿流体及其他物质的来源，碳酸盐胶结物与现今浅层地下水氧同位素组成差异巨大而与变质水同位素组成具有相似性，反映了盆地演化过程中活动热流体对成岩作用的影响.包裹体的氢、氧同位素组成可表征成矿溶液的演化特征，砂岩碳酸盐胶结物包裹体更富集氢的轻同位素和氧的重同位素，表明发生了明显的“氧-18漂移”.碳酸盐胶结的成矿溶液表现出“受热雨水”的同位素组成特征，反映了深源活动热流体对成岩作用的影响.      

黄骅坳陷千米桥地区奥陶系胶结物地层学及其在裂缝研究中的应用

在不同时期，由于埋藏深度不同，成岩环境的氧化还原性不同，形成的胶结物的特征也就不同。有些情况下，胶结物期次之间是连续沉淀的，即呈“整合接触”。而有些情况下，两个期次之间曾发生过溶蚀，形成“不整合接触”。有些孔隙和裂缝形成早，其内胶结物的期次齐全，而有些孔隙和裂缝形成晚，就会缺失一些期次。因此，胶结物可以像地层一样进行划分和对比。据此可以分析成岩环境的变化，判断孔隙和裂缝形成的时期等。由于成岩环境的变化常与构造运动有关，因此胶结物地层学的研究可以间接地分析构造运动发生的时期。黄骅坳陷千米桥地区奥陶系碳酸盐岩的裂缝和孔隙中，充填了5期胶结物，每期胶结物阴极发光的特征不同，其中第二期与第三期胶结物之间存在溶蚀不整合。根据胶结物的特征，可划分出5期裂缝，形成于三叠纪、中晚白垩世、古近纪末、新近纪末等。     

碳酸盐岩中方解石胶结物的阴极发光环带与微量元素构成的关系——以塔河油田奥陶系碳酸盐岩为例

对塔河油田奥陶系碳酸盐岩中方解石胶结物的阴极发光性和微量元素构成研究发现,一些与大气水成岩环境有关的方解石胶结物显示出亮、暗相间阴极发光环带,微量元素含量与阴极发光环带之间具有良好的对应关系,亮带具有较高的Mn、Fe含量,暗带则具有较高的Sr、Na含量,显示方解石胶结过程中大气水作用强度的变化。这些碳酸盐矿物的阴极发光环带受元素构成变化控制,并反映成岩流体中元素含量的变化和/或结晶速率的变化,这在一定程度上与大气水环境相对开放的成岩条件有关。相对晚期的环带发光较亮,并具有较高的Mn和较低的Sr、Na含量,显示与加里东—海西期构造运动有关的古岩溶过程中大气水作用逐渐加强的总体成岩趋势。     

查干凹陷下白垩统砂岩储层碳酸盐胶结物成岩期次及形成机理

通过矿物学、岩石学和地球化学方法,分析了查干凹陷下白垩统巴音戈壁组碎屑岩储层中多期碳酸盐胶结物的特征及成因机理。结果表明,根据碳酸盐胶结物的组分和结构,从矿物学和成岩序列的角度,可划分出三期胶结物类型,分别是Ⅰ期泥晶方解石、Ⅱ期含铁方解石,以及Ⅲ期的铁方解石、白云石及少量铁白云石。碳氧同位素研究表明,Ⅰ期泥晶方解石胶结物形成于常温常压中,主要从过饱和的碱性湖水介质中析出,形成于早成岩阶段A期,早于压实期,对孔隙的形成起到保存作用;Ⅱ期铁方解石形成于早成岩阶段B期-中成岩阶段A期,受控于埋藏过程中的水岩作用影响,其中的碳酸根来源于有机酸脱羧产生的CO_2,而Ca~(2+)和Fe~(3+)来自长石类颗粒的溶解和黏土矿物的转化,该期胶结物主要充填在残余原生粒间孔和各类次生溶孔中,对储层以破坏作用为主;Ⅲ期碳酸盐胶结物主要形成于中成岩阶段B期,成岩环境由弱酸向弱碱性转化,黏土矿物转化释放Mg~(2+)和Fe~(3+),其中Fe~(3+)被烃类还原成低价铁,为Ⅲ期含亚铁碳酸盐胶结物提供了充足来源,该期胶结物与Ⅱ期胶结物类似,对储层形成也属于"破坏型成岩作用"。     

中韩第五次《东北亚地壳演化》学术研讨会在北京举行

新疆天山东部广泛发育晚石炭世碳酸盐岩隆。这些岩隆主要为生物丘,少数为生物滩及与岩隆有关的生物层,其中生物丘含大量灰泥和内碎屑。基本岩石类型为泥粒状灰岩、粒泥状灰岩、粒泥状－泥粒状灰岩,少量岩石类型包括颗粒岩、骨架岩和障积岩。成岩作用是碳酸盐岩隆发展演化的重要阶段和过程,在生物丘内,已经识别出四种重要的胶结物,即球粒泥晶、纤状方解石、放射轴状方解石和粒状方解石。尽管缺失典型的造礁生物,但通过岩石类型研究和微相分析,认为碳酸盐岩隆的形成主要取决于生物作用及古环境格局。本区碳酸盐岩隆可以同欧洲瓦尔索坦的岩隆对比     

龙虎泡地区高台子油层成岩作用及其对储集岩孔隙演化的影响

龙虚泡地区高台子油层储集岩基本上由岩屑长石粉砂岩组成。压实作用、胶结作用、溶蚀作用、粘土矿物的转化作用和交代作用对沉积岩 (物 )进行了改造。根据岩石的结构可以看出压实作用发育于早成岩阶段,方解石胶结物的结构和碳、氧稳定同位素组成说明方解石胶结作用发育于早成岩阶段。压实作用和方解石结作用对孔隙的减少起着决定性影响。长石和中基性火山岩岩屑的溶蚀作用使得孔隙有一定程度的增加。压实作用和胶结作用也阻止了自生石英的生长和次生孔隙带的形成。     

酒西盆地碎屑岩胶结物的形成问题

酒西盆地下白垩统陆相碎屑岩胶结物的形成关系到油气储集的重要问题,富铁的洪积扇沉积体系和非富铁的河流一湖泊沉积体系形成两种不同的胶结物组合类型,平面上可分为三带胶结物:混合胶结带、铁镁胶结带和浓聚成岩带。盆地边缘带是以铁、泥、钙为主的混合胶结物,中间为以碳酸铁镁矿物的白云石、铁白云石为主的胶结物,盆中带形成胶结物的浓聚成岩层,事实证明过渡的铁镁胶结带是最富于聚集油气的地带。本文还在纵向上探讨了泥质粘土矿物和碳酸盐胶结物的成岩变化。     

Siliciclastic grain breakage and displacement due to carbonate crystal growth: an example from the Lueders Formation (Permian) of north-central Texas, U.S.A.

The Lueders Formation (mid-Permian) in Baylor County, Texas, is an intercalated suite of fluvial siliciclastic, shallow marine siliciclastic, and shallow marine carbonate strata. There are at least two generations of carbonate cements (probably originally composed of calcite) in the fluvial sandstones where fractured grains are observed. These cements represent the initial stages of caliche formation. Cementation is envisioned as a two step process. In the first step, calcite cements form from supersaturated fluids in a freshwater, vadose environment as a meniscus cement at grain contacts. Areas of cement formation are restricted to these sites because fluid distribution is restricted to these sites. Stresses generated by the growth of cements at grain contacts are transmitted through and concentrated at quartz/quartz grain point-contacts until the stress is sufficient to fracture quartz grains, even though the ultimate strength of calcite is less than that of quartz, per unit area. This process occurs too rapidly to be accommodated by pressure solution. In the second phase of cementation, cement nucleation is no longer restricted by vadose conditions. In this phase, calcite growth can no longer result in quartz grain breakage; rather, the quartz grains are dispersed in poikilotopic calcite cement.     

微生物碳酸盐岩沉积学研究进展--基于第33届国际沉积学会议的综述

第33届国际沉积学会议于2017年10月9日-12日在法国图卢兹召开,微生物碳酸盐岩专题受到持续关注。在总结会议成果基础上,结合近年来国内外微生物沉积学文献以及现代微生物碳酸盐岩沉积考察,分析了微生物碳酸盐岩沉积学研究前沿及进展,包括:1）微生物席矿化产物及序列,认为矿化产物包括方解石（低Mg、高Mg、超高Mg）、文石、含铁、锰和钙的碳酸盐岩,镁-硅和黄铁矿等产物,矿化序列多样。2）微生物碳酸盐岩的元素记录,其中碳、氧、氮、磷、硫、铁、硅、砷等元素及同位素特征可能保留了微生物碳酸盐岩沉积和早期成岩的信息。3）纹层、凝块等微生物碳酸盐岩沉积结构机理及指示意义。4）微生物碳酸盐岩沉积环境,认为潮坪环境,特别是平均低潮面附近及其以上叠层石灰岩、凝块岩等微生物碳酸盐岩最为发育。依据国际微生物碳酸盐岩沉积学发展特点,本文针对国内相关领域进一步探讨了研究趋向,提出分类认识微生物碳酸盐岩现代沉积机理、重建古老微生物碳酸盐岩早期成岩过程、分类认识古老微生物碳酸盐岩沉积标志,这在当今微生物碳酸盐岩沉积学研究中显得尤为必要。     

Diagenetic model of carbonate rocks of Guri Member of Mishan Formation (Lower to Middle Miocene) SE Zagros basin,Iran

In order to understand the post-depositional history of carbonate rocks of Guri Member (Lower to Middle Miocene), three stratigraphic sections were selected in north Bandar-Abbas in southeast of Iran. Sampling was carried out, analyzed for selective parameters such as oxygen and carbon isotopic compositions (δ¹⁸O and δ¹³C) and interpreted in the present study. We recognized several diagenetic processes including micritization, cementation, neomorphism, compaction, dissolution, silicification, dolomitization, fracturing and vein filling. Some of the diagenetic processes occurred at different conditions, so in order to achieve precise interpretation, samples from different carbonate components such as, micrite, fracture cement, solution pore cement, intergranular cement, and some biotic allochems were analyzed. In this study micrite samples were subdivided into two groups including micro-spary and micrite. They were recognized under Cathodoluminescence microscope. In addition, micrite samples were classified into five groups based on their depositional environments: supratidal, lagoon, coral bar, open sea, and open basin. There were minor changes in stable isotope ratios based on the sedimentary environments, stratigraphy successions, and micro-spary or micrite properties. In this study, similar calcite cements in petrography studies were differentiated by stable isotope data. Those calcite cements have formed in different diagenetic environments such as meteoric and burial cements. Paragenetic sequence of carbonate rocks were interpreted by integration of petrographic and isotopic studies. We have reconstructed diagenetic models of Guri Member into four stages including marine, meteoric, burial, and uplifting.     

Diagenesis of early Permian high‐latitude limestones,Lower Parmeener Supergroup,Tasmania

The Darlington (Sakmarian) and Berriedale (Artinskian) Limestones are neritic deposits that accumulated in high‐latitude environments along the south‐eastern margin of Pangea in what is now Tasmania. These rocks underwent a series of diagenetic processes that began in the marine palaeoenvironment, continued during rapid burial and were profoundly modified by alteration associated with the intrusion of Mesozoic igneous rocks. Marine diagenesis was important but contradictory; although dissolution took place, there was also coeval precipitation of fibrous calcite cement, phosphate and glauconite, as well as calcitization of aragonite shells. These processes are interpreted as having been promoted by mixing of shelf and upwelling deep ocean waters and enabled by microbial degradation of organic matter. In contrast to warm‐water carbonates where meteoric diagenesis is important, the Darlington and Berriedale Limestones were largely unaffected by meteoric diagenesis. Only minor dissolution and local cementation took place in this diagenetic environment, although mechanical compaction was ubiquitous. Correlation with burial history curves indicates that chemical compaction became important as burial depths exceeded 150 m, promoting precipitation of extensive ferroan calcite. This effect resulted from burial by rapidly deposited, overlying, thick, late Permian and Triassic terrestrial sediments. This diagenetic pathway was, however, complicated by the subsequent intrusion of massive Mesozoic diabases and associated silicifying diagenetic fluids. Finally, fractures most probably connected with Cretaceous uplift were filled with late‐stage non‐ferroan calcite cement. This study suggests that both carbonate dissolution and precipitation occur in high‐latitude marine palaeoenvironments and, therefore, the cold‐water diagenetic realm is not always destructive in terms of diagenesis. Furthermore, it appears that for the early Permian of southern Pangea at least, there was no real difference in the diagenetic pathways taken by cool‐water and cold‐water carbonates.     

Shallow-marine carbonate cementation in Holocene segments of the calcifying green alga Halimeda

Early-diagenetic cementation of tropical carbonates results from the combination of numerous physico-chemical and biological processes. In the marine phreatic environment it represents an essential mechanism for the development and stabilization of carbonate platforms. However, diagenetic cements that developed early in the marine phreatic environment are likely to become obliterated during later stages of meteoric or burial diagenesis. When lithified sediment samples are studied, this complicates the recognition of processes involved in early cementation, and their geological implications. In this contribution, a petrographic microfacies analysis of Holocene Halimeda segments collected on a coral island in the Spermonde Archipelago, Indonesia, is presented. Through electron microscopical analyses of polished samples, this study shows that segments are characterized by intragranular cementation of fibrous aragonite, equant High-Mg calcite (3.9 to 7.2 Mol% Mg), bladed Low-Mg calcite (0.4 to 1.0 Mol% Mg) and mini-micritic Low-Mg calcite (3.2 to 3.3 Mol% Mg). The co-existence and consecutive development of fibrous aragonite and equant High-Mg calcite results initially from the flow of oversaturated seawater along the aragonite template of the Halimeda skeleton, followed by an adjustment of cement mineralogy towards High-Mg calcite as a result of reduced permeability and fluid flow rates in the pores. Growth of bladed Low-Mg calcite cements on top of etched substrates of equant High-Mg calcite is explained by shifts in pore water pH and alkalinity through microbial sulphate reduction. Microbial activity appears to be the main trigger for the precipitation of mini-micritic Low-Mg calcite as well, based on the presumable detection of an extracellular polymeric matrix during an early stage of mini-micrite Low-Mg calcite cement precipitation. Radiocarbon analyses of five Halimeda segments furthermore indicate that virtually complete intragranular cementation in the marine phreatic environment with thermodynamically/kinetically controlled aragonite and High-Mg calcite takes place in about 100 years. Collectively, this study shows that early-diagenetic cements are highly diverse and provides new quantitative constraints on the rate of diagenetic cementation in tropical carbonate factories.     

大港滩海区第三系湖相混积岩的成因与成岩作用特征

大港滩海第三系沙河街组一段下部分布的混积岩主要为陆源碎屑质-碳酸盐混积岩, 其次为碳酸盐质-陆源碎屑混积岩和含碳酸盐-陆源碎屑混积岩.其中白水头地区的混积岩发育于辫状河-扇三角洲前缘水下分流河道沉积体系之中,为相缘渐变混合沉积的产物;而马东-马东东地区的混积岩发育于重力流沉积体系之中,为浊流沉积的产物.本区混积岩主要经历了压实作用、胶结作用和溶蚀溶解作用.孔隙流体的化学性质经历了由碱性到酸性,最后又回到碱性的变化历程.其中海绿石、微晶方解石、部分石英溶蚀和连生方解石为碱性流体条件下的共生组合;次生加大石英、油气侵位、溶蚀溶解、高岭石为酸性条件下的共生组合;伊利石、绿泥石、钠长石化、孔隙充填方解石和白云石为碱性流体条件下的共生组合.