四川盆地东部建南地区三叠系须家河组低孔低渗储集层特征及形成机理

四川盆地建南地区三叠系须家河组为辫状河三角洲—湖泊沉积体系,其储集层的岩石类型为辫状河三角洲沉积的岩屑砂岩、长石质岩屑砂岩、岩屑质石英砂岩。储集层平均孔隙度5.96%,平均渗透率0.044×10-3μm2,具有明显的低孔低渗特征。须家河组储集层主要形成于三角洲辫状河道沉积,辫状河侧向改道频繁,砂泥混杂,颗粒分选及磨圆均较差,砂岩成分成熟度和结构成熟度均较低,不利于原生孔隙的发育;在早期成岩过程中,压实作用损失大量原生孔隙,压实作用损失的孔隙度一般占孔隙损失的60%～85%。随后的胶结作用使得砂岩更加致密,胶结物使孔隙减少12%～18%;此外,研究区须家河组缺乏易溶解的物质成分,长石和碳酸盐胶结物的含量较低,致使后期溶蚀作用微弱,因溶蚀作用增加的孔隙度平均为1%,最高达2.5%。     

鄂尔多斯盆地长北气田山西组二段低孔低渗储层特征及形成机理

长北气田山西组二段主要为三角洲平原分支河道沉积的石英砂岩和岩屑砂岩,其埋藏深度中等（2 700～2 950 m）,但物性较差（孔隙度和渗透率平均分别为5.2%,0.7×10-3μm2）,属于低孔低渗的致密储层。造成低孔低渗的主要原因是：该套砂岩形成于三角洲平原含煤酸性环境,砂岩中原始孔隙水介质呈酸性,碳酸钙处于不饱和状...     

四川盆地东部建南地区三叠系须家河组低孔低渗储集层特征及形成机理*

四川盆地建南地区三叠系须家河组为辫状河三角洲—湖泊沉积体系,其储集层的岩石类型为辫状河三角洲沉积的岩屑砂岩、长石质岩屑砂岩、岩屑质石英砂岩。储集层平均孔隙度5.96％,平均渗透率0.044×10^-3μm²,具有明显的低孔低渗特征。须家河组储集层主要形成于三角洲辫状河道沉积,辫状河侧向改道频繁,砂泥混杂,颗粒分选及磨圆均较差,砂岩成分成熟度和结构成熟度均较低,不利于原生孔隙的发育;在早期成岩过程中,压实作用损失大量原生孔隙,压实作用损失的孔隙度一般占孔隙损失的60％～85％。随后的胶结作用使得砂岩更加致密,胶结物使孔隙减少12％～18％;此外,研究区须家河组缺乏易溶解的物质成分,长石和碳酸盐胶结物的含量较低,致使后期溶蚀作用微弱,因溶蚀作用增加的孔隙度平均为1％,最高达2.5％。     

鄂尔多斯盆地榆林气田山西组2段砂岩成岩作用及孔隙演化

榆林气田下二叠统山西组2段为一套辫状河三角洲沉积,储集岩主要为石英砂岩、岩屑石英砂岩,平均孔隙度5.36%,平均渗透率4.58×10-3μm2,是典型的低孔低渗储层。以岩心观察为基础,结合薄片鉴定、扫描电镜、阴极发光及物性分析等资料进行研究,认为山2段砂岩经历了压实作用、胶结作用、交代作用、溶解作用、粘土杂基的充填作用等多种成岩作用,目前已达到晚成岩阶段A期。成岩作用是控制该区储层物性的关键因素,孔隙演化经历了原生孔隙的破坏、次生孔隙的形成和次生孔隙的破坏三个阶段。各类次生孔隙占总孔隙度的55.3%,其中岩屑溶孔18.4%,粒间溶孔10.8%,晶间孔26.1%。     

鄂尔多斯盆地上古生界层序格架内的成岩作用

鄂尔多斯盆地上古生界主要发育石英砂岩、岩屑砂岩、杂砂岩、“牛毛毡砂岩”、黑色石英砂岩等五种砂岩类型。这些砂岩具有成份成熟度较高、结构成熟度中—低、以正粒序为主、粒级普遍为中粗粒、储层填隙物类型多、含量变化大的特点。经历了三个重要成岩阶段:早成岩压实期—原生孔隙大量破坏损失期，中成岩A期—有机酸溶蚀—次生孔隙发育期，中成岩B期—埋藏压溶再胶结成岩期。在SQ8主要发育压溶、高岭石溶蚀、石英次生加大等成岩作用。SQ11主要发育硅质胶结、碳酸盐胶结成岩作用。成岩相可分为三级五类，即Ⅰ强压溶—石英加大相；Ⅱ压溶—碳酸盐溶蚀—高岭石交代相及溶蚀—弱杂基充填—高岭石交代相；Ⅲ强压实—粘土胶结相及强压实—碳酸盐胶结、交代相。区内储层整体为低孔低渗的致密砂岩储层，以发育次生孔隙为主，包括粒间溶孔、粒内溶孔和高岭石晶间孔，原生孔隙较少保留。通过对沉积砂体展布、储层成岩相类型及储集性能的综合分析，对有利的储层分布区带进行了预测。     

柴达木盆地乌南油田N12、N22碎屑岩储层特征及其影响因素分析

利用岩石和铸体薄片、扫描电镜、元素分析、压汞等分析测试手段,特针对N12和N22碎屑岩储层特征、成岩作用以及影响因素,对30余口井的样品和资料进行了分析研究。结果表明,乌南油田N12和N22砂岩储层岩石类型为长石岩屑砂岩和岩屑长石砂岩;经历的主要成岩作用类型有粘土膜（粘土环边）的形成、机械压实作用、胶结作用、交代作用和溶解作用。砂岩储层孔隙类型主要是次生孔隙和原生粒间孔隙,其中次生粒间溶孔占绝对优势,其次是基质内微孔隙和裂缝孔隙。孔隙度多为8%～18%,渗透率多为0.5×10-3～10×10-3 μm2,属中低孔低渗储层。影响研究区储层物性的主要因素有沉积相带、成岩作用和孔隙结构,其中最有利的储集砂体微相为分流河道和河口坝（细砂岩和粉砂岩相）,其次为远砂坝粉砂岩相,间湾薄层砂岩储集性能差。胶结作用和溶蚀作用是影响乌南油田N12和N22储层的最主要的成岩作用。     

四川盆地马路背地区上三叠统须家河组致密砂岩储层成因分析

马路背构造位于四川盆地东北部,该地区须家河组发育致密砂岩储层,却形成了“高产、稳产”的规模气藏。论文充分利用各种岩矿分析化验资料,从岩石学特征、成岩作用、孔隙演化等方面深入探讨了马路背地区须二段（T₃x2）致密砂岩储层的成因。结果表明:马路背地区须家河组以大巴山变质岩为母岩沉积了一套三角洲前缘中粒岩屑砂岩和石英砂岩;无论是石英砂岩还是岩屑砂岩,无论埋深大小,铸体薄片下孔隙均不发育,扫描电镜偶见微孔,物性很差;强烈的埋藏压实作用造成各种孔隙的缩小与消失;早燕山期（199~100 Ma）、中晚燕山期（100~65 Ma）、喜山期（65 Ma以来）等多期构造强挤压进一步造成孔隙减小和消失,构造压实减孔量大约4%;埋藏压实与构造强压实减孔的同时,产生了不同规模断层和裂缝（颗粒裂纹—粒间微裂缝—层间断层）,沟通微孔,形成断层—裂缝—微孔隙组成的断缝储集体。这类储集体主要受构造应力大小控制,构造挤压最强的部位,裂缝最发育;其次受岩性和砂岩厚度控制,中—薄层石英砂岩中最发育。     

鄂尔多斯盆地北部伊盟地区山西组碎屑岩储层特征分析

伊盟地区早二叠世早期山西组发育的冲积扇的扇中砂、砾质辫状河道砂体、曲流点坝及三角洲平原分流纂和体是本区的主要储集砂体。夺主要为富杂基、富岩屑的石英砂岩及岩屑砂岩。储层总体上具有低孔低渗、非均质性强、次生孔隙占主导地位的特点,并按照同 点砂坝、分流河道、砂、砾质辫状河道沉积的次疗储层物性依次变差。依据孔喉分布特点将山西组碎屑岩储层归为这四种类型中孔低渗型、低孔低渗型、致密型和超致密型,它们的物性依次     

鄂尔多斯盆地上三叠统延长组长6油层组储集层成岩作用及其影响因素

鄂尔多斯盆地延长组长6油层组储集层是受沉积作用和成岩作用共同控制的典型低孔低渗储集层.长6油层组储集层主要为长石砂岩、岩屑长石砂岩和长石岩屑砂岩.盆地北部砂体具有长石含量高和石英含量低的特点,西南地区具有长石含量低、石英含量高和杂基含量高的特点.储集空间以剩余粒间孔和次生溶蚀孔为主.主要成岩作用类型有压实作用、胶结作用...     

涠西南凹陷西北陡坡带流三段砂砾岩储层特征与主控因素

通过岩心观察、薄片鉴定、扫描电镜、X射线衍射分析等实验手段,结合物性、有机质演化、埋藏史、测录井等资料,研究涠西南凹陷西北陡坡带流三段砂砾岩储层储集性能、成岩特征及物性主控因素.结果表明:（1）流三段储层岩石类型以岩屑砂岩为主,岩性以粗粒级砂砾岩、含砾粗砂岩为主,储集空间以粒内溶孔、残余粒间孔、铸模孔等为主,物性变化大,以低孔特低渗、中孔低渗、中孔中渗、高孔高渗为特征,非均质性强.（2）持续的压实作用是物性变差的主要原因,碳酸盐胶结和自生粘土矿物充填使部分原生孔隙丧失,高泥质含量部位表现为早期强压实;粗粒级砂岩的中-强溶蚀作用有利于次生孔隙的发育,而微裂缝是深层砂砾岩储层的重要渗流通道之一.西北斜坡带流三段扇三角洲水下分流河道发育厚层的砂砾岩、含砾粗砂岩,杂基含量低,压实作用较弱,是研究区的优质储层发育带;湖底扇压实作用强,微裂缝提供了有机酸性流体活动的渗流通道,砂砾岩储层发生次生溶蚀使储集性能得以改善,为深层相对有利储层.      

神府解家堡区上古生界致密砂岩储层特征及主控因素

神府解家堡区构造上位于鄂尔多斯盆地东缘晋西挠褶带,上古生界自下而上发育本1段、太2段、山2段和千5段等多套致密砂岩储集层.储层岩石类型以石英砂岩、岩屑石英砂岩、长石石英砂岩、岩屑砂岩和长石岩屑砂岩为主,自下而上储层石英含量呈递减、岩屑和长石含量呈递增趋势.储集空间类型以粒间溶孔、粒内溶孔、晶间孔和微裂缝为主,储层最大孔隙半径总体偏小,孔隙中值半径较小,排驱压力中等,储层孔隙以小孔—微孔为主.本溪组海相障壁—潮坪沉积、太原组浅水三角洲沉积、山西组三角洲沉积和石千峰组陆相辫状河沉积演化序列下,岩石成分成熟度和结构成熟度自下而上降低,储层空间展布呈层多而薄、砂—泥—煤岩交互特征.成岩作用类型以压实、胶结、溶蚀作用为主,局部发育高岭石化和微裂缝.以沉积相带、岩石类型和成岩作用类型作为3个控制端元,以孔隙度和渗透率为标准,上古生界致密砂岩储层可划分为4个大类和10个亚类,优势相和强溶蚀、弱胶结作用下的Ⅰ类储层孔隙度大于8%,渗透率大于0.5 mD,是最优质储层.     

苏北盆地金湖凹陷腰滩地区古近系阜宁组储层物性特征及其影响因素

苏北盆地金湖凹陷腰滩地区古近系阜宁组储层岩石类型以岩屑长石砂岩和长石砂岩为主,其成分成熟度中等,结构 成熟度中等到好。腰滩地区储层成岩作用主要包括压实、胶结、溶蚀和交代四种类型, 目前处于晚成岩阶段A期。研究区储 层的储集物性受成岩作用和构造运动的共同影响,主要表现为对孔隙度和渗透率的影响, 其中压实和胶结作用使储层原生 孔隙迅速减少、渗透率降低、储集物性变差,而溶解作用则是导致次生孔隙发育及改善砂岩储集性能的主要因素。压实作 用主要表现为刚性颗粒发生脆性破裂、塑性颗粒挤压变形或刚性颗粒嵌入塑性颗粒中、颗粒之间呈线接触和凹凸接触、碎 屑颗粒呈明显的定向排列等; 溶蚀作用表现为碳酸盐矿物的溶解; 胶结物主要为自生黏土矿物、碳酸盐和自生石英。交代作 用主要为碳酸盐胶结物交代石英、长石及岩屑颗粒及碳酸盐胶结物之间的相互交代等。构造运动使局部的储层物性得到改 善。     

泌阳凹陷核三下亚段砂岩成岩作用及储集性

泌阳凹陷东部核三下亚段砂岩储层由辨状河三角洲成因的长石砂岩及岩屑长石砂岩组成。主要成岩作用包括压实、石英和长石次生加大、晶粒状方解石胶结、溶解、自生绿泥石等，演化程度已达到晚成岩Ｂ亚期。成岩作用使砂岩原生孔隙体系发生强烈变化。各种成岩作用对储集性有不同影响，孔隙度的减少主要与压实及碳酸盐胶结作用有关；石英和长石次生加大及自生粘土衬边经常使喉道堵塞，对渗透率危害较大；溶解作用形成的次生孔隙及喉道对砂     

新疆三塘湖盆地马朗凹陷侏罗系西山窑组沉积特征及沉积模式

在岩心观察的基础上,结合录井资料、重矿物分析及地震资料,对三塘湖盆地马朗凹陷西山窑组物源方向、沉积相展布及沉积模式进行研究。研究认为马朗凹陷西山窑组主要发育辫状河三角洲和湖泊相2种沉积相。西山窑组下段沉积时期,辫状河三角洲在湖盆北侧大面积分布,辫状河三角洲前缘的水下分流河道频繁改道、迁移,相互切割,叠置成厚20～50m连片分布的砂体。西山窑组上段沉积时期,马朗凹陷以湖泊相沉积为主,有小规模的辫状河三角洲发育,局部发育滩坝砂体。西山窑组沉积整体呈现出一个水进过程。分析化验数据表明,西山窑组砂岩以岩屑砂岩和长石岩屑砂岩为主,储集层胶结作用不强,以压实减孔为主,主要发育剩余粒间孔;储集层质量主要受控于沉积微相,水下分流河道砂体是最好的储集砂体。     

The effects of diagenesis on the reservoir characters in sandstones of the Late Cretaceous Pab Formation,Kirthar Fold Belt,southern Pakistan

The Maastrichtian Pab Formation in the southern part of Pakistan is composed of fine- to very coarse-grained texturally mature quartz arenite and subordinate sublitharenite varieties. The sandstones have undergone intense and complex diagenetic episodes due to burial and uplift. Diagenetic modifications were dependent mainly on the clastic composition of sandstone, burial depth and thrust tectonics. Diagenetic events identified include compaction, precipitation of calcite, quartz, clay minerals and iron oxide/hydroxide, dissolution and alteration of unstable clastic grains as feldspar and volcaniclithic fragments as well as tectonically induced grain fracturing. The unstable clastic grains like feldspar and lithic volcanic fragments suffered considerable alteration to kaolinite and chlorite. Dissolution and alteration of feldspar and volcanic lithic fragments and pressure solution were the main sources of quartz cements. Mechanical compaction and authigenic cements like calcite, quartz and iron oxide/hydroxide reduced the primary porosity, whereas dissolution of clastic grains and cements has produced secondary porosity. Chlorite coatings on clastic grains have prevented quartz cementation. Coarse-grained, thick bedded packages of fluviodeltaic, shelf delta lobe and submarine channels facies have higher average porosity than fine-grained, thin bedded and bioturbated sandstone of deeper shelf and abyssal plain environments and these facies are concluded to be possible future hydrocarbon prospects.     

西湖凹陷某构造低渗储层成岩演化研究

使用西湖凹陷某构造的常规岩石薄片、铸体薄片、扫描电镜及储层物性分析资料,利用视压实率、视胶结率和视溶蚀率等参数,定量研究了西湖凹陷某构造低渗储层成岩演化序列及孔隙演化过程。研究结果表明: (1)研究区低渗储层孔隙类型以次生溶蚀孔隙为主,粒间溶蚀孔是最主要的次生孔隙类型。(2)机械压实作用是储层低渗的主要因素,导致原始孔隙度损失达65%,溶蚀作用产生的次生溶蚀孔隙一定程度上使储层物性变好。(3)研究区处于中成岩阶段A2期和中成岩阶段B期,成岩演化序列为: ①脆性颗粒破碎,塑性颗粒变形,局部绿泥石衬边胶结; ②部分长石及岩屑早期溶解,早期石英次生加大; ③碳酸盐胶结并交代石英、长石等,石英颗粒发生溶蚀作用; ④碳酸盐、长石、岩屑等矿物溶蚀形成次生孔隙,石英次生加大; ⑤晚期铁方解石少量胶结、交代。该研究成果可为西湖凹陷低渗气藏优质储层的预测与评价提供科学依据。     

辫状河三角洲水下分流河道储层特征

以海安南地区堡1断块泰州组一段为例,在岩石薄片和压汞资料分析的基础上,从砂体的内部结构入手对水下分流河道储层特征进行了研究,将泰一段储层的孔隙结构划分为三种类型。经研究表明：泰一段辫状河三角洲前缘水下分流河道砂体内部结构单元为典型的中一低孔、中一低渗储层,碎屑组份成分成熟度和结构成熟度均较低,储层孔隙类型以次生孔隙为主,原生孔隙较不发育;填隙物为泥质杂基和碳酸盐矿物胶结物,属长石岩屑质砂岩和岩屑长石质砂岩;成岩作用主要发育压实作用、胶结交代作用和溶解溶蚀作用等,塑性颗粒的变形、碎屑颗粒的破裂甚至错断、石英次生加大、方解石及铁白云石交代碎屑组份、溶蚀现象等均较普遍。对各结构单元孔隙结构类型参数分析表明,水下分流河道内部结构单元河道主体砂岩储集性能好于河道侧缘,认为岩相类型和沉积环境是影响储层物性的原生因素。     

Fluvial, tidal and storm sedimentation in the Chilhowee Group (Lower Cambrian), northeastern Tennessee, U.S.A.

The Lower Cambrian Chilhowee Group of northeastern Tennessee consists of the Unicoi, Hampton and Erwin Formations, and is divided into four facies. The conglomerate facies occurs only within the lower 200 m of measured section (the Unicoi Formation) and consists of fine-grained to pebbly quartz wacke with rare thin beds of laminated siltstone. Low-angle to horizontally laminated, fine-grained sandstone with laminae and lenses of granules and pebbles represents upper flow-regime, overbank deposition within a braided stream system that was close to a coastline. Medium-scale, planar-tabular cross-stratified conglomerate in which megaripple bedforms are preserved is interpreted as representing deposition in interbar pools of braided channels, as flood stage waned and larger bedforms ceased to migrate. Large-scale, planar-tabular cross-stratified conglomerate beds represent migration of large transverse bars within a broad braided stream channel during high flood stage. The sandstone facies occurs throughout the Chilhowee Group, and is therefore interbedded with all other facies. It consists of mainly medium- to very coarse-grained, subarkosic to arkosic arenite. Thinly interbedded, laminated siltstone and sandstone, which may exhibit wavy or lenticular bedding, represents deposition during slack water periods between ebb and flood tides. Large-scale planar-tabular and trough cross-stratification reflects deposition within the deepest areas of subtidal channels, whereas medium-scale cross-stratification represents deposition in shallower water on shoals separating channels. Fining- and thinning-upward sequences most likely resulted from the longshore migration of channels and shoals. The hummocky facies occurs only in the Erwin Formation and consists of horizontally laminated to hummocky stratified, fine-grained arkosic to subarkosic arenite interbedded with equal amounts of bioturbated mudstone. It represents deposition between storm and fairweather wave-base by combined-flow storm currents. The quartz arenite facies is characterized by an absence of fine-grained units and lithologically consists of a super-mature, medium- to coarse-grained quartz arenite. Large-scale planar-tabular cross-stratification and abundant low-angle cross-stratification with rare symmetrical ripples (lower quartz arenite facies) occurs interbedded with the braided fluvial conglomerate facies, and was deposited within either a ridge-and-runnel system or a system of nearshore bars. Large-scale, planar-tabular cross-stratification (upper quartz arenite facies), which forms the top of two 40 m-thick coarsening-upward sequences of the type: hummocky faciessandstone faciesquartz arenite facies, probably represents deposition on sand ridges that formed on a sand-starved shelf as transgression caused the detachment and reworking of shoreface channel-shoal couplets. Palaeocurrent data for the Chilhowee Group are unimodal but widely dispersed from 0° to 180°, and exhibit a minor mode to the west. The data are interpreted to reflect the influence of longshore, tidal and storm currents. The ichnofossil assemblage changes upsection from one characterized only by Paleophycus to a Skolithos ichnofacies and finally to a Cruziana ichnofacies. The facies sequence, biogenic and palaeocurrent data reflect the interaction through time of (I) non-marine and marine processes; and (2) transgression coupled with shoreline progradation. The Chilhowee Group represents an overall deepening from terrestrial deposition to a marine shoreface that experienced both longshore and tidal currents, and finally to a storm shelf environment that periodically shoaled upward.