Early Miocene benthic foraminifera and biostratigraphy of the Qom Formation, Deh Namak, Central Iran

A total of 165 samples were collected from the Qom Formation investigated in a stratigraphic section north of Deh Namak, in Central Iran. From these, 35 genera and 47 species of benthic foraminifera were identified. The age of the studied section is Early Miocene (Aquitanian to Early Burdigalian) based on the occurrence of Borelis melo curdica, Meandropsina anahensis, Meandropsina iranica, Elphidium sp. 14, Peneroplis farsensis, and Triloculina tricarinata. The thickness of the Qom Formation is 401 m of which 161.2 m is early Burdigalian in age. Foraminiferal assemblages in the Deh Namak section are referable to the Borelis melo group-Meandropsina iranica Assemblage Zone and Miogypsinoides-Archaias-Valvulinid Assemblage Zone of [Adams, T.D., Bourgeois, F., 1967. Asmari biostratigraphy. Iranian Oil Operating Companies, Geological and Exploration Division, Report1074 (unpublished) 1–37.] described originally from the Asmari Formation.     

Revision of the age of the Qom Formation in the Central Iran Basin, Iran

The Qom Formation in the Central Iran Basin contains not only relatively abundant calcareous nannofossils and a small number of dinoflagellate cysts, but also a number of stratigraphically significant benthonic foraminifers and ostracods. Calcareous nannofossils reported for the first time from this formation include Coccolithus pelagicus, Cyclicargolithus abisectus, C. floridanus, Dictyococcites bisectus, D. scrippsae, Helicosphaera euphratis, Ericsonia fenestratus, Pontosphaera sp., Reticulofenestra dictyoda, R. minuta and Sphenolithus moriformis. Dinoflagellates include Homotryblium plectilum, Hystrichokolpoma rigaudiae, Operculodinium centrocarpum, Palaeocystodinium golzowense, Spiniferites pseudofurcatus and Thalassiphora pelagica. Benthonic foraminifers include Assilina aff. spira, Discocyclina sp., Neodiscocyclina cf. barkeri, Nummulites aff. variolarius, Operculina sp. and Orbitolites sp. Among the ostracods recovered are Alocopocythere dhansariensis, Asymmetricythere samalutensis, Bairdia montiformis, Cytherella jonesiana, Cytheretta virgulata, Cytheridea cf. bundensis, C. cf. scruposa, C. sp., Eopaijenborchella sp., Hermanites cf. grafica, Krithe oryza, K. cf. pernoides, Loxoconcha sp., Paracypris sp., Propontocypris zongbuensis, P. sp. and Xestoleberis sp. This assemblage indicates that the Qom Formation is Eocene in age instead of Middle-Late Oligocene to Early Miocene as previously determined.     

鄂尔多斯盆地上三叠统延长组三角洲沉积及演化

鄂尔多斯盆地上三叠统延长组广泛发育曲流河三角洲沉积,其总体沉积特征为：沉积体系及相带发育完整;成分成熟度及结构成熟度较高;发育各种沉积构造、动植物化石及生物遗迹构造。曲流河三角洲平原的分流河道具有复杂分支与决口历史,因此常呈交织状,受分流河道冲蚀作用的影响,河口坝不发育。曲流河三角洲主要形成于湖盆坳陷回返期。通过对岩相组合、骨架砂体的几何形态及盆地古地理背景的综合分析,认为延长组的环境演化反映了浅水台地型三角洲逐渐转变为陆上平原的过程。曲流河三角洲可形成良好的储层,是油气勘探的有利相带。     

Facies Analysis and Sequence Stratigraphy of the Qal’eh Dokhtar Formation (Middle–Upper Jurassic) in the West of Boshrouyeh, East Central Iran

The study area is located in the east Tabas Block in Central Iran. Facies analysis of the Qal’eh Dokhtar Formation (middle Callovian to late Oxfordian) was carried out on two stratigraphic sections and applied to depositional environment and sequence stratigraphy interpretation. This formation conformably overlies and underlies the marly-silty Baghamshah and the calcareous Esfandiar formations, respectively. Lateral and vertical facies changes documents low- to high energy environments, including tidal-flat, beach to intertidal, lagoon, barrier, and open-marine. According to these facies associations and absence of resedimentation deposits a depositional model of a mixed carbonate–siliciclastic ramp was proposed for the Qal’eh Dokhtar Formation. Seven third-order depositional sequences were identified in each two measured stratigraphic sections. Transgressive systems tracts (TSTs) show deepening upward trends, i.e. shallow water beach to intertidal and lagoonal facies, while highstand systems tracts (HST) show shallowing upward trends in which deep water facies are overlain by shallow water facies. All sequence boundaries (except at the base of the stratigraphic column) are of the no erosional (SB2) types. We conclude eustatic rather than tectonic factors played a dominant role in controlling carbonate depositional environments in the study area.     

Provenance,tectonic setting and age of the sediments of the Upper Disang Formation in the Phek District,Nagaland

Integrated petrographic and geochemical studies of sandstones, and geochemical studies of shales of turbidites from the Upper Disang Formation, Phek district, Nagaland have been carried out to determine their provenance, weathering conditions and tectonic setting. Paleomagnetic studies were carried out for magnetostratigraphic purposes. Studies indicate that most of these sediments were derived from felsic and mafic sources with minor contribution from low to medium grade metamorphic rocks. Most of the felsic components have been transported from distant sources as evidenced from extensive reworking of grains. The most likely source rocks are the granite/granite gneiss of the Karbi Anglong crystalline complex to the west of the study area. However, the bulk of the sediments have been contributed from nearby basic and ultrabasic sources. This would correspond to the fast rising Naga Ophiolite, which probably emerged above sea level during the Mid-Eocene. Prevailing high temperatures and humid climate caused intense chemical weathering of the source rocks. The sediments from the west were transported great distances by turbidity currents into an easterly deepening basin. Sediments from the nearby east were rapidly dumped on the seafloor causing rapid mixing, leading to textural and chemical immaturity. Paleomagnetic studies endorse published paleontological evidence to indicate that most of the sediments of the Upper Disang Formation were deposited during the Late Eocene. Deposition took place in a westward-migrating accretionary-prism complex in an active-margin setting at the convergence of the Indian and Burma plates. This was a rapidly-closing basin where anoxic conditions prevailed. Towards the end of the Eocene this basin closed completely with the destruction of the Tethyan Ocean.     

沙湾凹陷上乌尔禾组储层成岩作用及成岩相分析

二叠系上乌尔禾组为沙湾凹陷重要勘探目的层之一,主要发育岩性油气藏,但成岩作用的相关研究较少,阻碍该区上乌尔禾组深入勘探。在储层岩石学以及储集特征分析基础上,利用薄片观察、物性分析、扫描电镜以及能谱等实验手段,对上乌尔禾组成岩作用类型以及成岩相进行详细研究。发现研究区上乌尔禾组储层成岩作用包括压实作用、胶结作用以及溶蚀作用。结合大量成岩现象及特征,认为研究区上乌尔禾组成岩阶段为中成岩B期。综合成岩强度以及典型成岩现象,将研究区上乌尔禾组成岩相划分为强压实致密相、强压实中溶蚀相、中强压实方解石胶结弱溶蚀相、中强压实伊蒙混层包膜弱溶蚀相、中强压实沸石胶结弱溶蚀相,利用Fisher判别法建立各成岩相判别公式,并结合测井资料探索各成岩相的分布规律,为优质储层的预测提供依据。     

Depositional systems and sequence stratigraphy analysis of the Upper Callovian to Tithonian sediments in the Central and Western Kopet‐Dagh Basin,Northeast Iran

Upper Callovian to Tithonian (late Jurassic) sediments represent an important hydrocarbon reservoir in the Kopet‐Dagh Basin, NE Iran. These deposits consist mainly of limestone, dolostone, and calcareous mudstone with subordinate siliciclastic interbeds. Detailed field surveys, lithofacies and facies analyses at three outcrop sections were used to investigate the depositional environments and sequence stratigraphy of the Middle to Upper Jurassic interval in the central and western areas of the basin. Vertical and lateral facies changes, sedimentary fabrics and structures, and geometry of carbonate bodies resulted in recognition of various carbonate facies related to tidal flats, back‐barrier lagoon, shelf‐margin/shelf‐margin reef, slope and deep‐marine facies belts. These facies were accompanied by interbedded beach and deep marine siliciclastic petrofacies. Field surveys, facies analysis, parasequences stacking patterns, discontinuity surfaces, and geometries coupled with relative depth variation, led to the recognition of six third‐order depositional sequences. The depositional history of the study areas can be divided into two main phases. These indicate platform evolution from a rimmed‐shelf to a carbonate ramp during the late Callovian–Oxfordian and Kimmeridgian–Tithonian intervals, respectively. Significant lateral and vertical facies and thickness changes, and results obtained from regional correlation of the depositional sequences, can be attributed to the combined effect of antecedent topography and differential subsidence related to local tectonics. Moreover, sea‐level changes must be regarded as a major factor during the late Callovian–Tithonian interval. Copyright © 2015 John Wiley & Sons, Ltd.     

Characteristics and distribution of clay minerals and their effects on reservoir quality: Huagang Formation in the Xihu Sag,East China Sea Basin

Abstract

The characteristics and distribution of clay minerals and their effects on reservoir quality in the Huagang sandstones in the Xihu Sag, East China Sea Basin were studied by using X-ray diffraction, casting thin-sections, scanning electron microscopy, electron microprobe analysis, fluid inclusion analysis, constant-rate mercury injection and nuclear magnetic resonance. Clay minerals consist of kaolinite, chlorite, illite and illite–smectite mixed layer (I/S); kaolinite forms from dissolved feldspars, chlorite occurs as clay coatings that are transformed from clay precursors owing to the flocculation of suspended detrital clays or the crystallisation of pore fluids, and illite forms from the illitisation of detrital smectite, authigenic kaolinite and K-feldspars. Clay distribution is controlled by sedimentary environments, burial history and lithologies. Typical reservoirs in the western sub-sag are thin and developed in braided river facies at relatively shallow burial depths with clays dominated by kaolinite. However, typical reservoirs in the central inversion tectonic zone are thicker and developed in a braided delta front facies at deeper burial depths with clays mainly consisting of chlorite, illite and I/S. High-quality reservoirs are characterised by coarse granularity, high quartz content and low clay content with widespread development of chlorite coatings that inhibit quartz cements at low temperatures. At higher temperatures, the high-quality reservoirs develop more pores providing growth space for quartz cements and result in the coexistence of chlorite coatings and quartz cements. The high-quality reservoirs are controlled by their lithological characteristics rather than chlorite coatings. Illite and I/S clays create severe damage to reservoirs by reducing the size and connectivity of pore-throats.     

松辽盆地钱家店地区姚家组砂岩黏土矿物特征及其与铀矿化的关系

[研究目的]钱家店铀矿床位于松辽盆地西南部,含铀岩系为上白垩统姚家组.目的层中含有大量的黏土矿物,因此揭示姚家组砂岩黏土矿物特征,对铀的成矿作用探讨至关重要.[研究方法]本文通过系统的显微镜下鉴定、扫描电镜、X射线衍射等分析测试手段,对钱家店地区姚家组砂岩黏土矿物的镜下特征、成分及含量进行了系统的观察和研究.[研究结果...     

Depositional conditions of the coal-bearing Hirka Formation beneath Late Miocene explosive volcanic products in NW central Anatolia,Turkey

This work focuses on the relationship between the coal deposition and explosive volcanism of the Miocene basin, NW central Anatolia, Turkey. The coal-bearing Hirka Formation was deposited over the Galatian Andesitic Complex and/or massive lagoonal environments during the Miocene. The investigated lignite is a high ash (from 32 to 58%) and sulphur (from 1.43 to 3.03%) lignite which is petrographically characterised by a high humunite content. The mineral matter of the studied lignite samples is made up of mainly clay minerals (illite-smectite and kaolinite), plagioclase and quartz in Bolu coal field, clay minerals (illite-smectite, smectite and illite), quartz, calcite, plagioclase and gypsum in Seben coal field, quartz, K-feldspar, plagioclase and clay minerals (kaolinite and illite) in K?br?sc?k, and dolomite, quartz, clinoptilolite, opal CT and gypsum in Çaml?dere coal field. The differences in these four types of lignite with specific mineralogical patterns may be due to the explosive volcanic events and depositional conditions which changed from one coal field to the others. There is a zonation from SW to SE in the studied area for zeolites such as Opal CT+smectite-clinoptilolite-analcime-K-feldspar. Carbonate minerals are commonly calcite in Seben and K?br?sc?k coal fields. In Bolu, coal samples are devoid of calcite and dolomite. These analyses show that there is an increase in the amount of Mg and a decrease in the amount of Na from the northwestern part to the southern part in the study area.     

Hydrodynamics and petroleum migration in the Upper Ordovician Red River Formation of the Williston Basin

Simulations of petroleum migration within the Red River petroleum system of the Williston Basin show that petroleum generation and secondary migration preceded the onset of an active hydrodynamic regime that persists to the present day. Furthermore: (1) a better understanding of the eastern limit of the mature source rock area, which is largely facies controlled, is required to reduce exploration risk east of the Nesson Anticline, (2) the Red River play types that have been prosperous in southeastern Saskatchewan should extend considerable distances to the north, as well as throughout central Saskatchewan and western Manitoba, Canada, and (3) accumulations that may have developed in the southwest of the basin have likely been flushed and redistributed subsequent to the onset of hydrodynamics.     

准噶尔盆地南缘上三叠统黄山街组辫状河三角洲沉积

准噶尔盆地南缘上三叠统黄山街组主要为砾岩、含砾砂岩、砂岩、粉砂岩和泥岩构成的一套碎屑岩组合,野外沉积特征研究确定为典型的辫状河三角洲沉积。通过对沉积相、亚相、微相的详细研究,认为辫状河三角洲具有类似曲流河三角洲的层序结构和微相类型,但两者间也存在很大的差别。与曲流河三角洲相比,辫状河三角洲的三角洲平原亚相不仅沉积物的粒度较粗,而且辫状河道沉积较发育,河道间洪泛平原沉积不发育。辫状河三角洲前缘亚相也可以识别出水下分流河道、河口坝、席状砂和水下分流河道间等微相,水下分流河道沉积为主体。根据野外露头的追索研究,建立了准噶尔盆地南缘上三叠统黄山街组辫状河三角洲的沉积模式。从沉积物的岩性特征看,辫状河三角洲砾岩和含砾粗砂岩体具有分布较稳定、展布较广、储集物性较好的特点。     

Diagenetic and Depositional Impacts on the Reservoir Quality of the Upper Jurassic Arab Formation in the Balal Oilfield,Offshore Iran

The Kimmeridgian‐Tithonian aged Arab Formation, as the main reservoir of the Jurassic succession in the Balal oilfield, located in the offshore region of the Iranian sector of the Persian Gulf, is investigated in this study. The formation is composed of dolomites and limestones with anhydrite interbeds. Based on detailed petrographic studies, six microfacies are recognized, which are classified in four sub‐environments including supratidal, intertidal, lagoonal and the high energy shoal of a homoclinal carbonate ramp. The main diagenetic features of the studied succession include dolomitization, anhydritization, cementation, micritization, fracturing and compaction. Based on stable isotope data, dolomitization of the upper Arab carbonates is related to sabkha settings (i.e. evaporative type). In terms of sequence stratigraphy, three shallowing‐upward sequences are recognized, based on core and wireline log data from four wells of the studied field. Considering depositional and diagenetic effects on the reservoir quality, the studied facies are classified into eight reservoir rock types (RRT) with distinct reservoir qualities. Dolomitization has played a major role in reservoir quality enhancement, whereas anhydritization, carbonate cementation, and compaction have damaged the pore throat network. Distribution of the recognized RRTs in time and space are discussed within the context of a sequence stratigraphic framework.     

Build‐up and depositional dynamics of an arc front volcaniclastic complex: the Miocene Tepoztlán Formation (Transmexican Volcanic Belt,Central Mexico)

Volcanic terrains such as magmatic arcs are thought to display the most complex surface environments on Earth. Ancient volcaniclastics are notoriously difficult to interpret as they describe the interplay between a single or several volcanoes and the environment. The Early Miocene Tepoztlán Formation at the southern edge of the Transmexican Volcanic Belt belongs to the few remnants of this ancestral magmatic arc, and therefore is thought to represent an example of the initial phase of evolution of the Transmexican Volcanic Belt. Based on geological mapping, detailed logging of lithostratigraphic sections, palaeocurrent data of sedimentary features and anisotropy of magnetic susceptibility, mapping of two‐dimensional panels from outcrop to field scale, and geochronological data in an area of ca 1000 km², three periods in the evolution of the Tepoztlán Formation were distinguished, which lasted around 4 Myr and are representative of a volcanic cycle (edifice growth phases followed by collapse) in a magmatic arc setting. The volcaniclastic sediments accumulated in proximal to medial distances on partly coalescing aprons, similar to volcanic ring plains, around at least three different stratovolcanoes. These volcanoes resulted from various eruptions separated by repose periods. During the first phase of the evolution of the Tepoztlán Formation (22·8 to 22·2 Ma), deposition was dominated by fluvial sediments in a braided river setting. Pyroclastic material from small, andesitic–dacitic composite volcanoes in the near vicinity was mostly eroded and reworked by fluvial processes, resulting in sediments ranging from cross‐bedded sand to an aggradational series of river gravels. The second phase (22·2 to 21·3 Ma) was characterized by periods of strong volcanic activity, resulting in voluminous accumulations of lava and tuff, which temporarily overloaded and buried the original fluvial system with its detritus. Continuous build‐up of at least three major volcanic centres further accentuated the topography and, in the third phase (21·3 to 18·8 Ma), mass flow processes, represented by an increase of debris flow deposits, became dominant, marking a period of edifice destruction and flank failures.     

鄂尔多斯盆地富县—黄陵县地区上三叠统 延长组长6、长7浊积岩成岩作用

根据砂岩薄片、铸体薄片、扫描电镜、压汞等分析,对富县—黄陵县地区上三叠统延长组长6及长7油层组的浊积岩岩石学特征、成岩作用类型及其对孔隙的影响进行了研究.研究结果表明,该区长6及长7浊积岩主要为细粒长石砂岩.压实作用、胶结作用、交代作用和溶解作用是控制浊积岩储层物性演化的主要成岩作用,其中压实作用和胶结作用强烈破坏了浊积岩的原生孔隙,它们造成的平均孔隙度丧失分别为23.1％和6.5％,但早成岩阶段绿泥石薄膜的形成使浊积岩的一些原生孔隙得以保存.溶解作用和交代作用有效地改善了浊积岩的孔隙结构,从而提高了浊积岩储层的孔渗条件.     

伊拉克中部上白垩统Khasib组岩溶储层演化及异常高渗层成因

针对伊拉克艾哈代布(Ahdeb)油田Khasib组早期的注水突破难题, 本文以地球化学资料及取心薄片分析为基础, 结合区域沉积-构造演化背景, 对储层演化及异常高渗层的成因进行了研究, 并将储层演化划分为3个阶段: 沉积同生期、低沉降速率浅-中埋藏期和快速沉降深埋藏期。沉积同生期具两层高孔段: 即受同生岩溶改造形成的以砂屑粒间孔为主的Kh2-2-1砂屑颗粒灰岩和以藻屑铸模孔为主的Kh2-3-2藻屑泥粒灰岩。在此基础上, 浅-中埋藏期产生以走滑断裂为流体的运移通道, 以深部源岩降解形成的有机酸为溶蚀介质, 以同生期后形成的高孔层段为溶蚀的载体, 以非组构选择溶蚀作用为特征的埋藏有机酸岩溶, 它与同生期岩溶作用在时间上具有连续性, 形成的孔隙分布在空间上具有继承性。晚期地层快速沉降深埋藏期, 发生大规模烃类充注成藏, 阻止孔隙内水岩反应, 减弱储层内压实胶结破坏性成岩作用, 最终使得这两段具异常高渗透率特征。Kh2-2-1砂屑颗粒灰岩段以砂屑粒间孔、粒间溶孔、针状溶洞为主要孔隙类型, 以孔隙缩小型为主要喉道类型, 孔喉连通性好, 岩相区域分布稳定, 是造成早期注水突破的层段。总体而言, 本区异常高渗层的成因主要是: 优质储层的沉积基础及同生岩溶改造, 长期浅-中埋藏期有机酸溶蚀对储层的叠加和改造优化, 以及快速深埋藏期与烃类充注极好的耦合关系使其得以保存。     

Climatic and sea‐level control of Jurassic (Pliensbachian) clay mineral sedimentation in the Cardigan Bay Basin,Llanbedr (Mochras Farm) borehole,Wales

Early Jurassic climate is characterized by alternating cold and warm periods highlighted by studies based notably on oxygen isotopes measured on belemnite guards and other marine invertebrate shells. These climatic changes include changes in the hydrological cycle, and consequently weathering and runoff conditions. In order to clarify the erosion and weathering conditions during the Pliensbachian, this study determined the mineralogical composition of the clay fraction of 132 samples taken from the entire stage drilled in the Llanbedr (Mochras Farm) borehole (Cardigan Bay Basin). The clay mineral assemblages are composed of various proportions of chlorite, illite, illite/smectite mixed‐layers (R1 I–S), smectite and kaolinite, with possibly occasional traces of berthierine. The occurrence of abundant smectite indicates that the maximum burial temperature never exceeded 70°C. Consequently, clay minerals are considered mainly detrital, and their fluctuations likely reflect environmental changes. The variations in the proportions of smectite and kaolinite are opposite to each other. Kaolinite is particularly abundant at the base of the jamesoni Zone, in part coinciding with the δ¹³C negative excursion corresponding to the Sinemurian/Pliensbachian Boundary Event, and through the davoei Zone, whilst smectite is abundant in the upper part of jamesoni and base of ibex zones and through the subnodosus/gibbosus subzones of the margaritatus Zone. The kaolinite‐rich intervals reflect an intensification of hydrolysis and an acceleration of the hydrological cycle, while the smectite‐rich intervals indicate a more arid climate. The spinatum Zone is characterized by a distinct clay assemblage with abundant primary minerals, R1 I–S, kaolinite reworked from previously deposited sediments or from Palaeozoic rocks, and probably berthierine originating from contemporaneous ironstone‐generating environments of shallower waters. This mineralogical change by the end of the Pliensbachian likely reflects a transition from a dominant chemical weathering to a deeper physical erosion of the continent, probably related to a significant sea‐level fall consistent with a glacio‐eustatic origin.     

达县—宣汉地区长兴组礁滩白云岩成岩过程中的孔隙演化

川东北达县—宣汉长兴组礁滩白云岩具有良好的油气储集潜力。作者通过大量岩石常规薄片、铸体薄片观察研究,发现该礁滩白云岩储层储集空间主要为次生成因的晶间孔、晶间溶孔、粒间粒内溶孔、生物体腔内溶孔和生物格架间溶孔。这些孔隙的形成和演化除了受沉积作用、构造作用和有机质热演化史的影响外,还受成岩作用的控制。首先在海底-暴露-浅埋藏环境下,压实及胶结使原生孔隙基本消失;而准同生混合水白云石化及早期暴露溶蚀作用改变了沉积物内部结构,形成众多微小孔隙的网络及溶孔,为后期形成大量孔隙创造了条件。其次在中—深埋藏环境下,强烈的重结晶作用和溶蚀作用使得岩石形成大量的次生孔隙,大大提高了礁滩白云岩的储集性能。     

西藏改则上三叠统日干配错组生物礁组成特征及演化

西藏改则地区上三叠统日干配错组发育有大量生物礁,造礁生物有六射珊瑚、钙质海绵和钙藻类,附礁生物为双壳类、有孔虫、苔藓虫、棘皮动物、腹足类、腕足类等。单个礁体的生物发育顺序可分为5个阶段,自下而上依次为:钙藻类+双壳类+腹足类→钙藻类+双壳类+六射珊瑚→六射珊瑚→六射珊瑚+钙质海绵+苔藓虫→生物碎屑。与此相对,各礁体岩性演化顺序也包括5段:生物碎屑灰岩→障积岩→骨架岩→粘结岩→生物碎屑和内碎屑灰岩。台地边缘生物礁的发育经历了3个旋回,各旋回组成结构相似,礁体均由礁基、礁核和礁顶构成,生物礁经历了生物礁奠基、初期繁盛、最大繁盛和生物礁衰亡4个演化阶段。旋回Ⅰ和旋回Ⅱ规模较大,内部构成复杂,旋回Ⅲ规模较小,内部构成较简单,自下而上构成一个海侵大背景下的次级进积序列。     

鄂尔多斯盆地中部姚店油田上三叠统长4＋5储层砂岩的成岩作用

根据砂岩薄片、铸体薄片、扫描电镜、X－衍射等分析,对姚店油田三叠系延长组长4+5油层砂体的岩石学特征、成岩作用阶段划分、成岩作用类型及其对孔隙的影响进行了研究。研究结果表明,该区长4+5储层储集砂体成分主要以长石砂岩为主。成岩作用类型包括压实作用、胶结作用和溶蚀作用。砂岩经历了早期成岩阶段A、B期和晚期成岩阶段A期（A1、A2 期）的成岩演化过程。早期的压实作用、多种矿物胶结作用是使物性变差的2个重要因素,但早成岩阶段形成的绿泥石膜保护了一些砂岩的原生孔隙;晚成岩阶段A期的溶蚀作用,特别是长石的溶蚀是储层物性变好的重要成岩控制因素