鄂尔多斯盆地三叠系延长组深水砂岩与致密油的关系<sup>*</sup>

付金华, 邓秀芹, 张晓磊, 罗安湘, 南珺祥. (2013)鄂尔多斯盆地三叠系延长组深水砂岩与致密油的关系^* [J]. 古地理学报, 15(5): 624-634
Fu Jinhua, Deng Xiuqin, Zhang Xiaolei, Luo Anxiang, Nan Junxiang. (2013)Relationship between deepwater sandstone and tight oil of the Triassic Yanchang Formation in Ordos Basin[J]. Journal Of Palaeogeography, 15(5): 624-634. DOI:10.7605/gdlxb.2013.05.050 复制到剪切板

Permissions

鄂尔多斯盆地三叠系延长组深水砂岩与致密油的关系^*

付金华^1,², 邓秀芹^2,³, 张晓磊^2,³, 罗安湘^2,³, 南珺祥^2,³

1 中国石油长庆油田分公司,陕西西安 710018

2 低渗透油气田勘探开发国家工程实验室,陕西西安 710018

3 中国石油长庆油田分公司勘探开发研究院,陕西西安 710018

第一作者简介: 付金华,男,1962年生,博士,教授级高级工程师,现任中国石油长庆油田分公司副总地质师,长期从事油气地质综合研究及勘探管理工作。

收稿日期:2013-05-09

基金:*国家科技重大专项“大型油气田及煤层气开发”(编号:2011ZX05044,2011ZX05001-004)资助

摘要

鄂尔多斯盆地湖盆中部地区三叠系延长组长6油层组中下部和长7油层组中上部大面积发育深水砂岩,这种砂岩具有厚度大、平行于湖盆长轴方向连续分布的特征。根据沉积结构、构造及接触关系,将深水砂岩划分为砂质碎屑流成因的砂岩、浊流成因的砂岩、滑塌成因的砂岩及三角洲前缘成因的砂岩等4种沉积类型。在储集层矿物学、岩石学特征研究的基础上,提出深水砂岩的沉积特征(如粒度细、云母和绿泥石等塑性颗粒含量高、陆源碳酸盐岩岩屑与伊利石杂基发育等)是造成储集层抗压实能力较差、胶结强烈、储集层致密的关键因素;在有利成藏条件分析中提出深水砂岩致密储集层处于油源中心、与烃源岩互层共生是形成大面积非常规致密油资源的重要控制因素。

关键词: 鄂尔多斯盆地; 延长组; 深水砂岩; 致密油

中图分类号:P618.130.2 文献标志码:A 文章编号:1671-1505(2013)05-0624-11

Relationship between deepwater sandstone and tight oil of the Triassic Yanchang Formation in Ordos Basin

Fu Jinhua^1,², Deng Xiuqin^2,³, Zhang Xiaolei^2,³, Luo Anxiang^2,³, Nan Junxiang^2,³

1 Changqing Oilfield Company,PetroChina,Xi'an 710018,Shaanxi

2 National Engineering Laboratory for Exploration and Development of Low-Permeability Oil & Gas Fields,Xi'an 710018,Shaanxi

3 Research Institute of Exploration & Development of Changqing Oilfield Company,PetroChina,Xi'an 710018,Shaanxi

About the first author:Fu Jinhua,born in 1962,doctor,is a professor senior engineer and vice-chief geologist in Changqing Oilfield Company,PetroChina.Now he is engaged in comprehensive study and exploration management of oil and gas geology.

Abstract

A large area of deep water sandstone was developed during the depositional period between lower-mid Chang 6 and mid-upper Chang 7 intervals of Yanchang Formation of Triassic in the center of Ordos Basin. The large area sandstone had a great thickness and distributed continuously paralleled to the long axis of the basin. According to the sedimentary textures and structures and contact relationship,deepwater sandstone could be divided into four types, i.e., sandy debrite,slump stone,turbidite and delta front sandstones. On the base of reservoir characteristics of mineralogy and petrology,it was put forward that the sedimentary characteristics of deepwater sandstone,such as fine granularity,high content of plastic particles as mica and chlorite,as well as developing terrigenous matrix of carbonate and illite,were key factors that caused intense compaction and cementation in reservoir.Through analysis of favorable reservoir conditions, it was the important controlling factors for the forming of massive unconventional tight oil that deepwater sandstone locating in the center of oil source rock, and syngenetically interbedding with hydrocarbon source rock.

Key words: Ordos Basin; Yanchang Formation; deepwater sandstone; tight oil

Show Figures

鄂尔多斯盆地石油勘探已经历了40余年的历史发展, 上世纪70年代在古地貌成藏理论指导下发现了马岭、城壕等一批“ 小而肥” 的侏罗系油藏, 上世纪80— 90年代在三角洲成藏理论的指导下发现了安塞、志靖岩性油藏(李克勤, 1986)。进入21世纪, 辫状河三角洲、湖盆中部富砂、多层系复合成藏等理论认识相继提出, 有效地指导了西峰、华庆、姬塬大油田的快速探明(付金华等, 2004, 2005; 姚泾利等, 2007, 2011; 邓秀芹等2010, 2011a; 杨华等, 2012, 2013), 石油勘探进入大发展阶段, 实现了由盆地周边三角洲找油向湖盆中部深水砂岩找油的转化, 勘探层系由浅层向深层的转移, 勘探对象由常规油藏到低渗透油藏再到非常规致密油的转变。近几年来, 深水砂岩和非常规油气资源的研究引起了极大的关注(姚泾利等, 2012; 杨华等, 2013; 邹才能等, 2013), 并取得了重要的勘探成果, 成为鄂尔多斯盆地石油勘探最主要的目标之一, 有力地推动了长庆油田储量和产量的快速增长。鄂尔多斯盆地延长组深水砂岩和致密油规模大、特征明显、代表性强, 该项研究对类似盆地的石油地质评价研究和有利勘探区带优选具有重要的意义。

1 地质背景

印支期, 华北板块和扬子板块最终完成了汇聚拼接, 一方面形成了横亘中国大陆中央、绵延上千千米的秦岭— 大别褶皱带(Mattauer et al., 1985; Hacker et al., 2000; 张国伟等, 2001), 另一方面对其南北两侧分布的盆地演化产生了重要的影响。其北侧的华北盆地逐渐萎缩, 海水彻底退出, 从此开始进入鄂尔多斯大型内陆湖盆的演化阶段。当时鄂尔多斯盆地范围北起阴山山系, 南至秦岭商丹缝合线一带, 东达太行山地区, 西抵贺兰山西缘断裂— 六盘山西缘断裂一带。该地区沉积了一套千余米厚的河湖相碎屑岩系, 被称作三叠系延长组, 其自下而上可划分为长10— 长1共10个油层组(付金华等, 2005, 2012a)(图1)。鄂尔多斯湖盆的演化具有振荡发展的特征, 经历了初始沉降(长10期)、快速发展(长9— 长8期)、强烈拗陷(长7期)、逐渐萎缩(长6— 长4期)至消亡(长3— 长1期)的完整发展过程。受周边山系和隆起区构造演化、古气候、古地形等方面的影响, 不同沉积期、不同体系其沉积类型、岩性组合存在较大的差异。受印支运动影响, 长7期湖盆强烈拗陷, 半深湖— 深湖面积超过了10× 10⁴ km², 为中晚三叠世最大湖泛阶段, 是该盆地烃源岩发育的主要时期(邓秀芹等, 2008); 长7中晚期— 长6期处于湖退的早期阶段, 湖盆中部地区主要发育半深湖— 深湖沉积, 面积为(1.5~3.5)× 10⁴ km²(图 2), 是深水砂岩发育的主要时期。

	Figure Option View Download New Window
	图1 鄂尔多斯盆地延长组地层柱状图Fig.1 Stratigraphic column of the Yanchang Formation in Ordos Basin

2 深水砂岩特征

传统地质理论认为半深湖、深湖环境下盆地往往处于欠补偿状态, 泥岩发育而砂岩贫乏。近年来, 通过构造事件、沉积物源、湖盆底形及沉积演化等方面深入分析, 结合生产实践, 认识到在湖盆沉积中心发育大规模深水砂岩。

2.1 深水砂岩的沉积类型及特征

三叠系延长组长7中上部— 长6中下部的泥质岩呈灰黑色、黑色和褐黑色, 发育水平层理(图 3-a, 3-b), 系由悬浮物质或溶解物质沉淀而成, 显示了还原环境、静水和深水的特征。层面基本不含植物茎、杆化石, 常发育细小的鱼牙齿和鳞片化石; 砂泥岩界面沟模、槽模(图 3-c)、刷模等底模构造丰富; 砂、泥岩还常常呈薄的韵律互层。该阶段随着基准面的降低, 盆地周缘母源区地质体的风化剥蚀及供屑能力逐渐增强, 三角洲建设作用明显, 并不断向盆地腹部进积, 为沉积中心大面积厚层砂体的形成奠定了物质基础。压实恢复、层降度(公式:Φ =arctan((A-B)/S), A和B为地层原始厚度, S为A与B两点间水平距离)计算表明, 湖盆中部发育深水坡折, 其中西南地区坡度较陡, 东北地区坡度较缓(图 4)。延长组长6、长7油层组沉积物中记录了大量的凝灰岩薄层、砂岩岩脉(图 3-d)、包卷层理、砂泥搅浑构造(图 3-e)、阶梯状微断层(图 3-f)、枕状构造(图 3-g)等, 指示了较动荡的构造环境(田景春等, 2012)。由此可见, 该期具备在湖盆中部形成大型深水砂岩体的物源供给、盆地底形和构造条件。

自上世纪50年代以来, 许多古代和现代的深水砂岩被发现和报道, 并以鲍马序列作为识别浊积岩的标准(Bouma, 1962, 2000), 使得长期以来大部分深水砂岩被解释为浊积岩, 并且就浊积岩和浊积相的划分开展了大量的研究(Morris, 1971; Lowe, 1982; Pikering et al., 1986; Mutti, 1992)。但Shamugam(2000, 2003)从过程沉积学的角度明确指出鲍马序列的沙纹层理、平行层理等段具有牵引流的特征, 严格意义上不是重力流, 更不是浊积岩。近年来, 许多学者针对湖盆中部广泛发育的延长组深水砂岩开展了研究, 取得了不同的认识(陈全红等, 2007; 邓秀芹等, 2010; 李相博等, 2011; 付金华等, 2012b; 廖纪佳, 2013)。在对大量岩心资料的岩性、沉积结构和构造分析的基础上, 本次研究认为鄂尔多斯盆地中部长6— 长7油层组厚层砂岩主要为砂质碎屑流、浊流和滑塌成因的砂岩以及三角洲成因的砂岩。

	Figure Option View Download New Window
	图2 鄂尔多斯盆地延长组长6和长7油层组沉积相 a— 长7油层组沉积相; b— 长6油层组沉积相Fig.2 Sedimentary facies of the Chang 6 and Chang 7 intervals of Yanchang Formation in Ordos Basin

2.1.1 滑塌成因的砂岩

主要为灰绿色、灰褐色的细砂岩夹粉砂岩。在重力或地震、火山活动等外力驱动下, 三角洲前缘或早期重力流沉积物发生液化, 由于半深湖、深湖泥质沉积物含水量高、粒度细, 形成了细腻光滑的滑动面, 在斜坡区沉积体易于在滑动面上滑动、整体搬运(图 3-h)。在垮塌过程中, 砂泥搅浑揉皱可形成各种各样的变形、包卷构造、砂岩岩脉等。滑塌体中常携带大量的角砾状泥岩撕裂屑。重力事件结束后仍恢复深湖、半深湖的泥质沉积, 因此滑塌体与上下岩层界面截然分开, 厚度较大, 一般从几十厘米至十几米。

Figure Option
View Download New Window

图3 鄂尔多斯盆地延长组深水沉积岩心特征
a— 宁66井, 长7, 暗色泥岩, 发育水平层理; b— 木23井, 长7, 暗色泥岩; c— 庄24井, 长6, 槽模; d— 西44井, 长7, 砂岩岩脉; e— 西44井, 长7, 砂泥搅浑构造; f— 环96井, 长6, 阶梯状微断层; g— 环60井, 长6, 球枕构造; h— 庄38井, 长6, 滑塌沉积; i— 庄12井, 长7, 砂质碎屑流沉积Fig.3 Sedimentary characteristics of deepwater deposition of the Yanchang Formation in Ordos Basin

2.1.2 砂质碎屑流成因的砂岩

主要为细砂岩、粉砂岩, 夹泥砾和泥岩撕裂屑。湖盆中部的液化沉积体在搬运过程中, 细砂、粉砂与黏土形成较高密度的混合物, 顺斜坡快速搬运, 并冲蚀、卷起下伏未固结的半深湖、深湖软泥和固结岩层, 在地形平坦地区快速堆积, 因此细砂岩中常含有泥岩撕裂屑和固结的岩块。撕裂屑大小混杂, 无分选性和定向性(图 3-i)。砂质碎屑流中也存在大量的砂泥搅浑现象。与上下岩层呈顶、底突变和顶部渐变、底部突变的接触关系最常见。该类砂体规模相对较大, 厚度从几十厘米至十余米, 具块状层理。

	Figure Option View Download New Window
	图4 鄂尔多斯盆地庆阳— 安塞剖面延长组沉积期湖盆底形特征Fig.4 Bottom shape feature of Qingyang-Ansai section during the depositional period of Yanchang Formation in Ordos Basin

	Figure Option View Download New Window
	图5 鄂尔多斯盆地铜川瑶曲露头剖面延长组长6油层组多期浊积岩叠加形成均质的块状深水砂岩Fig.5 Homogeneous and massive deepwater sandstone formed by superposition of multistage turbidites of the Chang 6 interval of Yanchang Formation at Yaoqu section in Tongchuan, Ordos Basin

2.1.3 浊流成因的浊积岩

主要为灰绿色、灰褐色粉砂岩、细砂岩夹深灰色泥质粉砂岩。在重力流的前端、侧翼或顶部常产生浊流, 具递变悬浮特征, 形成向上变细的正粒序。研究区浊积岩粒度普遍较细, 一般下部为细砂岩, 向上渐变为粉砂岩、泥质沉积, 为底部突变、顶部渐变的岩性接触关系。当湍流支撑的主要为细砂、粉砂颗粒而缺少泥质颗粒时, 由于粒度变化微小, 裸眼很难分辨, 因此常常描述为均匀块状砂岩。图5是鄂尔多斯盆地南缘铜川瑶曲露头剖面长6油层组下部的一套砂岩, 显示了多期浊积岩叠加形成了均质块状深水砂岩。仅从粒度上, 裸眼难以分辨该砂岩内部的粒度变化及沉积旋回, 然而砂岩内部发育火焰构造, 具有成层性多期发育的特征。单期砂厚度相对较小, 一般厚5~27 cm, 累计厚约3 m。该处湍流支撑的碎屑主要是细砂、粉砂, 缺少泥质物质, 因此火焰状构造显示为“ 砂火焰” , 而非常见的“ 泥火焰” 。由此可知, 多期的浊积岩叠加是厚层均质深水砂岩形成的主要形式。

2.1.4 三角洲成因的砂岩

粒度相对较粗, 主要为灰绿色、灰褐色细砂岩, 夹少量中砂和粉砂的组分。延长组长6沉积期, 在白豹等(图 2)东北沉积体系的前端, 主要沉积物为颗粒较细的砂岩、泥岩和粉砂质泥岩, 其中砂岩具有牵引流特征, 常发育平行层理、板状交错层理、槽状交错层理等牵引流形成的沉积构造, 可以细分出三角洲水下分流河道、远砂坝等沉积微相。水下分流河道砂体呈厚层状或向上变细的正旋回, 测井曲线为箱型或钟型, 单砂层厚度一般3~15 m; 远砂坝砂体常与深水泥岩互层, 测井曲线显示为指状, 或具反旋回的特征, 单层厚度一般0.5~3, m。

2.2 厚层砂体的结构特征

在湖盆中部地区, 深水砂岩厚度大, 连续性好 (图 6), 但沉积组合复杂, 不同流态的流体往往随着时间、空间的变化相互转化, 相伴出现(图 7), 因此, 不能简单地将鄂尔多斯盆地中部延长组深水沉积归结为某一种或两种沉积类型。同一个地区、同一油层组砂体往往是多种沉积类型的组合, 砂体叠置关系及储集层物性存在较大差异。

2.2.1 白豹地区

位于东北物源体系缓斜坡前端及坡折带, 受东北物源控制, 厚层砂体主要为水下分流河道叠加远砂坝、滑塌砂体(图 7)。平面上呈带状、群状分布(图 6), 厚度一般为40~75, m。储集层物性相对较好, 孔隙度主要为8.6%~13.2%, 渗透率为0.2× 10^-3~1.25× 10^-3 μ m²。

2.2.2 华池地区

位于湖底平原, 为西南和东北物源体系交汇区, 厚层砂体主要为滑塌、砂质碎屑流夹浊流成因的砂岩(图 7), 呈带状展布(图 6), 厚度一般35~80 m, 储集层纵向非均质性较强, 物性相对较差, 孔隙度主要为8.2%~12.8%, 渗透率为0.05× 10^-3~0.63× 10^-3 μ m²。

2.2.3 合水地区

位于西南深水陡斜坡的坡脚。厚层砂体为浊流、滑塌和砂质碎屑流成因的砂岩叠加而成(图 7), 其中浊积岩在砂岩中的比重较其他地区大。砂体呈带状、孤立透镜状展布(图 6), 厚度一般20~50, m。物性较差, 孔隙度一般为7.8%~11.5%, 渗透率为0.05× 10^-3~0.28× 10^-3 μ m²。

2.3 深水砂岩的分布

深水砂岩主要分布于湖盆沉积中心的延长组长6中下部和长7油层组中上部。砂体垂向叠合厚度较大, 一般20~80 m, 局部地区连续厚度达上百米, 呈北西— 南东向沿湖盆长轴方向延伸, 砂带长约150 km, 宽15~70 km, 面积达8000 km²。该砂带为西南、西部和东北物源在湖盆中央汇聚的结果, 以华池— 王家大庄为界, 该线以东主要接受了东北物源的供给, 该线以西主要受到西南和西部物源的影响(邓秀芹等, 2010)。在西南和西部地区厚层砂体与三角洲前缘砂体之间存在一个沿相带界线分布的砂岩匮乏区, 东部体系厚层砂体围绕三角洲呈群状、带状(图 7)。长7中晚期至长6期, 湖盆逐渐萎缩, 深水砂岩的分布范围逐渐减小, 厚度逐渐变薄, 横向连续性也变差。

	Figure Option View Download New Window
	图6 鄂尔多斯盆地延长组长7和长6油层组砂体展布 a— 长7油层组砂体展布; b— 长6油层组砂体展布Fig.6 Sandbody distribution of the Chang 6 and Chang 7 intervals of Yanchang Formation in Ordos Basin

	Figure Option View Download New Window
	图7 鄂尔多斯盆地中部地区延长组长6油层组深水砂岩结构模式Fig.7 Structural model of deepwater sandbody in the Chang 6 interval of Yanchang Formation in center of Ordos Basin

3 深水砂岩与致密油

致密油为一种非常规油气资源, 一般认为致密油是一种以游离态或吸附态赋存于油页岩或与之互邻共生的致密砂岩或碳酸盐岩中的、未经过长距离运移的石油聚集, 单井一般无自然产能或产量较低。但目前对致密储集体的物性尚无统一的标准, 杨华等(2013)提出致密储集层孔隙度小于10%, 基质负压渗透率小于0.1× 10^-3 μ m²; 匡立春等(2012)提出储集层孔隙度小于10%, 空气渗透率小于2× 10^-3 μ m²(基质负压渗透率小于0.2× 10^-3 μ m²)为致密储集层。鄂尔多斯盆地中生界延长组致密油资源丰富, 目前已拥有渗透率小于1× 10^-3, μ m²的石油探明地质储量超过10× 10⁸ t。湖盆中部延长组长6、长7深水砂岩分布区为致密油形成的有利地区。

3.1 深水砂岩与致密储集层的关系

深水砂岩具有粒度细、云母和绿泥石等塑性颗粒含量高、陆源的碳酸盐岩岩屑及伊利石杂基发育的特征(表 1), 这造成储集层抗压实能力较差、胶结强烈、储集层致密。不同沉积类型的储集层物性存在较大差异, 其中三角洲砂岩储集层物性相对较好, 储集层孔隙度平均10.32%, 渗透率0.53× 10^-3 μ m²; 重力流沉积储集层孔隙度平均9.99%和8.25%, 渗透率仅0.2× 1 $\begin{matrix} {0^{-}}^{3} \end{matrix}$ μ m²左右(表 2)。

表1 鄂尔多斯盆地中部延长组深水砂岩储集层填隙物含量统计 Table1 Statistics of interpore fillings of deepwater sandstone of the Yanchang Formation in center of Ordos Basin

表2 鄂尔多斯盆地中部延长组深水砂岩储集层孔隙组成及物性统计 Table2 Statistics of pore types and physical properties of deepwater sandstone of the Yanchang Formation in center of Ordos Basin

沉积条件决定了储集层埋藏过程中的被强烈压实。延长组深水砂岩以细砂岩和粉砂岩为主, 而且碎屑组成中云母、绿泥石等塑性颗粒含量较高, 平均5.1%~6.7%(表 1)。粒度细、塑性组分含量高造成储集层的抗压实能力较弱, 在深埋藏过程中压实作用强烈, 颗粒间主要为线接触、点— 线接触, 一些层段和地区还可见凹凸接触(图 8-a)。采用Beard 和 Weyl(1973)提出的等大球体颗粒原始孔隙度计算公式得出砂岩原始孔隙度约为37.7%~39.1%, 结合杂基、胶结物和孔隙统计(表 1, 表2), 计算出压实损失的孔隙度达14.1%~16.3%(表 3)。相比之下, 重力流沉积物(上里塬— 合水长6和湖盆中部长7储集层)比白豹长6三角洲砂岩储集层粒度更细, 以粉砂岩为主, 而且岩屑和伊利石杂基含量相对较高, 因此压实作用更加强烈, 主要为线接触、凹凸接触。

陆源杂基含量对储集层渗流能力具有重要的影响。三角洲成因砂岩与重力流成因的砂岩中, 杂基含量差异较大, 其中白豹长6三角洲砂岩伊利石含量平均为5.6%, 上里塬— 合水长6和湖盆中部长7重力流砂岩由于是快速堆积形成, 因此颗粒分选差, 杂基含量高, 伊利石含量分别达到8.3%和10.0%。陆源杂基伊利石呈片状, 成岩中晚期形成的伊利石呈丝缕状, 它们充填于孔隙中或附着于颗粒表面, 具有较强的水敏和速敏效应, 严重影响了储集层的渗流能力。因此, 杂基含量高也是重力流成因储集层比三角洲成因储集层物性差的重要影响因素。

沉积条件决定了储集层成岩作用的增孔与减孔效应。如白豹地区延长组长6三角洲砂岩储集层绿泥石膜较发育, 含量大于1%(表 1; 图8-b), 它一方面抑制了石英的生长, 另一方面增大了颗粒的半径, 增强了储集层抗压能力, 有效保护了储集层的原生孔隙, 白豹长6储集层残余粒间孔平均为1.5%, 明显高于重力流沉积储集层(表 2)。深水砂岩富含白云岩岩屑, 在成岩期有机酸作用下, 白云岩岩屑溶解, 释放出大量的碳酸根离子, 为成岩作用中晚期铁方解石(图 8-c)和铁白云石(图 8-d)大量生成奠定了物质基础。不同的沉积类型, 碳酸盐胶结物的含量和类型都存在较大的差异, 其中白豹地区延长组长6三角洲储集层主要为铁方解石胶结物, 平均含量为3.3%, 铁白云石含量平均仅1.0%; 而延长组长6、长7重力流沉积储集层中, 铁方解石含量分别为3.3%和2.7%, 铁白云石胶结物含量比三角洲砂岩储集层明显增多, 平均分别为2.5%和2.8%(表 2)。铁白云石呈晶粒状充填在粒间孔和各类溶蚀孔中, 常常还可以见到铁白云石沿着白云岩岩屑边缘生长, 形成铁白云石加大边的现象(图 8-d)。晚期碳酸盐胶结作用使得孔隙明显减少, 是储集层致密化的重要因素。

	Figure Option View Download New Window
	图8 鄂尔多斯盆地中部延长组深水砂岩岩石学特征 a— L51井, 长7, 塑性颗粒变形充填孔隙; b— B210井, 长6, 碎屑颗粒绿泥石膜发育; c— S139井, 长6, 铁方解石胶结充填孔隙; d— B464井, 长6, 白云岩屑的铁白云石加大边Fig.8 Petrology characteristics of deepwater sandstone of the Yanchang Formation in center of Ordos Basin

表3 鄂尔多斯盆地白豹地区延长组长6深水砂岩储集层成岩作用及孔隙演化史 Table3 Diagenesis and porosity evolution history of deepwater sandstone in the Chang 6 interval of Yanchang Formation in Baibao area, Ordos Basin

白豹地区延长组长6三角洲储集层与上里塬— 合水地区长6重力流储集层孔隙度基本相当, 约10%, 但渗透性上却存在差异。前者平均渗透率为0.53× 10^-3 μ m², 后者为0.23× 10^-3 μ m², 储集层研究表明, 受沉积类型的控制, 两个区块的粒度、绿泥石膜的发育程度、碳酸盐胶结物及伊利石杂基含量等方面都存在较大的差异, 导致了两个区块储集层渗流能力的较大差异。

3.2 致密油形成的有利条件

在鄂尔多斯盆地深水区, 延长组优质烃源岩与砂岩大面积分布, 互层共生, 形成了良好的源储配置关系。长7沉积期为最大湖泛期, 沉积了一套富有机质的油页岩、暗色泥岩, 厚度20~60, m区域面积超过5× 10⁴ km²。烃源岩有机质类型好, 以Ⅰ 、Ⅱ ₁型干酪根为主, 平均有机碳值为13.75%。成熟度适中, R_O值一般为0.9%~1.1%, 进入生排烃高峰阶段, 具有高产烃率(产油率达400 kg/t)、高排烃效率(一般为55%~90%)(杨华等, 2005)、广覆式生烃的特征。长6暗色泥岩有机碳含量为2.18%, 干酪根类型以Ⅱ ₁型为主, 也具有一定生烃能力。

	Figure Option View Download New Window
	图9 鄂尔多斯盆地延长组致密油油藏剖面Fig.9 Reservoir profile of tight oil accumulation of the Yanchang Formation in Ordos Basin

长6、长7期, 在湖盆中部地区形成了以重力流沉积为主的、纵横交织的、庞大的“ 满盆砂” 的储集层分布格局, 为石油聚集提供了有利的储集空间。在成岩过程中, 受沉积物粒度、岩石组分的控制, 深水砂岩经历了强烈的压实和胶结作用, 形成了致密砂岩储集层, 但它处于油源中心或与烃源岩互层共生(图 9), 具有优先捕获油气的优势, 有利于非常规致密油的形成。

晚侏罗世— 早白垩世, 在快速埋藏过程中, 升温、欠压实及生烃增压等共同作用下, 延长组长7优质烃源岩层产生了显著的超压, 压力系数一般为1.2~1.8(邓秀芹等, 2011b)。因此, 尽管长6、长7深水砂岩储集层岩性致密、物性差, 但在长7烃源岩层的超压充注作用下, 成熟的油气仍可进入到上、下邻近的致密储集层中, 形成大面积的致密油。

3.3 致密油的分布

鄂尔多斯盆地延长组致密油分布于该含油系统的“ 核心区域” :平面上, 位于湖盆的中部, 即环县、华池、庆阳、正宁一带, 为中晚三叠世的沉积中心; 纵向上, 位于延长组中部与油页岩互层共生或紧邻的致密砂岩储集层中, 石油未经大规模长距离运移, 直接进入到长6、长7油层组, 形成储集层渗透率均小于1× 10^-3 μ m²的湖盆中部长6、长7致密油。

4 结论

1)鄂尔多斯盆地延长组长6、长7期具备大型深水砂岩形成的物源供给、湖盆底形和构造动力条件。在湖盆沉积中心发育大面积深水砂岩, 砂体垂向叠合厚度较大, 呈北西— 南东向沿湖盆长轴方向延伸。

2)深水砂岩主要为砂质碎屑流、浊流和滑塌成因的沉积, 局部地区发育三角洲沉积。砂岩组合类型复杂, 不同流态的流体往往随着时空变化相互转化, 相伴出现。其中, 白豹地区厚层砂体主要为水下分流河道叠加远砂坝、滑塌砂体; 华池地区主要为滑塌、砂质碎屑流夹浊流成因的砂岩; 合水地区为浊流、滑塌和砂质碎屑流成因的砂岩叠加而成。

3)深水砂岩具有粒度细、云母和绿泥石等塑性颗粒含量高、陆源的碳酸盐岩岩屑和伊利石杂基较多的特征, 造成储集层抗压实能力较差、胶结强烈, 使储集层在成岩过程中发生致密化。

4)深水砂岩处于油源中心或与烃源岩互层共生, 具有优先捕获油气的优势, 有利于非常规致密油的形成。

作者声明没有竞争性利益冲突.

参考文献

View Option

[1]	陈全红, 李文厚, 高永祥, 等. 2007. 鄂尔多斯盆地上三叠统延长组深湖沉积与油气聚集意义[J]. 中国科学(D辑), 37(S1): 39-48. [文内引用:1]
[2]	邓秀芹, 付金华, 姚泾利, 等. 2011 a. 鄂尔多斯盆地中及上三叠统延长组沉积相与油气勘探的突破[J]. 古地理学报, 13(4): 443-455. [文内引用:1]
[3]	邓秀芹, 李文厚, 李士祥, 等. 2010. 鄂尔多斯盆地华庆油田延长组长6油层组深水沉积组合特征[J]. 地质科学, 45(3): 745-756. [文内引用:3]
[4]	邓秀芹, 蔺昉晓, 刘显阳, 等. 2008. 鄂尔多斯盆地三叠系延长组沉积演化及其与早印支运动关系的探讨[J]. 古地理学报, 10(2): 159-166. [文内引用:1]
[5]	邓秀芹, 姚泾利, 胡喜锋, 等. 2011 b. 鄂尔多斯盆地延长组超低渗透岩性油藏成藏流体动力系统特征及其意义[J]. 西北大学学报(自然科学版), 41(6): 1044-1050. [文内引用:1]
[6]	付金华, 高振中, 牛小兵, 等. 2012 b. 鄂尔多斯盆地环县地区上三叠统延长组长6₃砂层组沉积微相特征及新认识[J]. 古地理学报, 14(6): 695-706. [文内引用:1]
[7]	付金华, 郭正权, 邓秀芹. 2005. 鄂尔多斯盆地西南地区上三叠统延长组沉积相及石油地质意义[J]. 古地理学报, 7(1): 34-44. [文内引用:2]
[8]	付金华, 李士祥, 刘显阳, 等. 2012 a. 鄂尔多斯盆地上三叠统延长组长9油层组沉积相及其演化[J]. 古地理学报, 14(3): 269-284. [文内引用:1]
[9]	付金华, 罗安湘, 喻建, 等. 2004. 西峰油田成藏地质特征及勘探方向[J]. 石油学报, 25(2): 25-29. [文内引用:1]
[10]	匡立春, 唐勇, 雷德文, 等. 2012. 准噶尔盆地二叠系咸化湖相云质岩致密油形成条件与勘探潜力[J]. 石油勘探与开发, 39(6): 657-667. [文内引用:1]
[11]	李克勤. 1986. 陕甘宁盆地晚三叠世的三角洲[J]. 沉积学报, 4(1): 86-95. [文内引用:1]
[12]	李相博, 付金华, 陈启林, 等. 2011. 砂质碎屑流概念及其在鄂尔多斯盆地延长组深水沉积研究中的应用[J]. 地球科学进展, 26(3): 286-295. [文内引用:1]
[13]	廖纪佳, 朱筱敏, 邓秀芹, 等. 2013. 鄂尔多斯盆地陇东地区延长组重力流沉积特征及其模式[J]. 地学前缘, 20(2): 29-39. [文内引用:1]
[14]	田景春, 王文之, 王峰, 等. 2012. 鄂尔多斯盆地华池—庆阳地区上三叠统延长组长6油层组古地震变形构造及砂体叠置关系[J]. 古地理学报, 14(3): 269-284. [文内引用:1]
[15]	杨华, 张文正. 2005. 论鄂尔多斯盆地长7段优质油源岩在低渗透油气成藏富集中的主导作用: 地质地球化学特征[J]. 地球化学, 34(2): 147-154. [文内引用:1]
[16]	杨华, 付金华, 何海清, 等. 2012. 鄂尔多斯盆地华庆地区低渗储集层岩性大油区形成与分布[J]. 石油勘探与开发, 39(6): 641-648. [文内引用:1]
[17]	杨华, 李士祥, 刘显阳. 2013. 鄂尔多斯盆地致密油、页岩油特征及资源潜力[J]. 石油学报, 34(1): 1-11. [文内引用:3]
[18]	姚泾利, 邓秀芹, 赵彦德, 等. 2012. 鄂尔多斯盆地延长组致密油特征[J]. 石油勘探与开发, 40(2): 150-158. [文内引用:1]
[19]	姚泾利, 王克, 宋江海, 等. 2007. 鄂尔多斯盆地姬塬地区延长组石油运聚规律研究[J]. 岩性油气藏, 19(3): 32-37. [文内引用:1]
[20]	姚泾利, 王琪, 张瑞, 等. 2011. 鄂尔多斯盆地华庆地区延长组长6砂岩绿泥石膜的形成机理及其环境指示意义[J]. 沉积学报, 29(1): 72-79. [文内引用:1]
[21]	张国伟, 张本仁, 袁学城, 等. 2001. 秦岭造山带与大陆动力学[M]. 北京: 科学出版社, 1-855. [文内引用:1]
[22]	邹才能, 杨智, 崔景伟, 等. 2013. 页岩油的地质特征、形成机制及发展对策[J]. 石油勘探与开发, 40(1): 14-26. [文内引用:1]
[23]	Bouma A H. 1962. Sedimentology of Some Flysch Deposits: A Graphic Approach to Facies Interpretation[M]. Amsterdam: Elsevier Publishing Company, 1-264. [文内引用:1]
[24]	Bouma A H. 2000. Coarse-grained and fine grained turbidite systems as end member models: Applicability and dragers[J]. Petroleum Geology, 17(1): 137-143. [文内引用:1]
[25]	Hacker B R, Ratschbacher L, Webb L, et al. 2000. Exhumation of ultrahigh continental crust in east central China: Late Triassic-early Jurassic tectonic unroofing[J]. Journal of Geophysical Research, 105(B6): 13339-13364. [文内引用:1]
[26]	Lowe D R. 1982. Sediment gravity flows: Depositional models with special reference to the deposits of high-density turbidity currents[J]. Sediment Research, 152(1): 279-297. [文内引用:1]
[27]	Mattauer M, Matte P H, Malqvieille J, et al. 1985. Tectonic of the Qinling belt: Build-up and evolution of eastern Asia[J]. Nature, 317(10): 496-500. [文内引用:1]
[28]	Morris R C. 1971. Classification and interpretation of disturbed bedding typed in Jackfork flysch rocks(Upper Mississippian)Ouachita Mountain, Arkansas[J]. Journal of Sedimentary Petrology, 4: 410-424. [文内引用:1]
[29]	Mutti E. 1992. Turbidite Sand stones[M]. Milan, Italy: AGIP Special Publication, 275. [文内引用:1]
[30]	Pikering K T, Stow D A V, Watson M P, et al. 1986. Deep water facies, process and models: A review and classification scheme for modern and ancient sediments[J]. Earth Science Review, 23: 75-174. [文内引用:1]
[31]	Shanmugam G. 2000. 50 years of the turbidite paradigm: Deep-water processes and facies models, a critical perspective[J]. Marine and Petroleum Geology, 17: 285-342. [文内引用:1]
[32]	Shanmugam G. 2003. A preliminary experimental study of turbidite fan deposits discussion[J]. Journal of Sedimentary Research, 73(5): 838-841. [文内引用:1]

2007

0.0

... 近年来,许多学者针对湖盆中部广泛发育的延长组深水砂岩开展了研究,取得了不同的认识(陈全红等,2007 ...

2011

0.0

邓秀芹, 付金华, 姚泾利, 等. 2011 a. 鄂尔多斯盆地中及上三叠统延长组沉积相与油气勘探的突破[J]. 古地理学报, 13(4): 443-455.

The Ordos Basin lies across Shaanxi，Gansu，Ningxia，Inner Mongolia and Shanxi Provinces of middle-western China.Its area reaches 2.5×10 5 km 2 .The Middle-Upper Triassic Yanchang Formation，more than 1000 m thick，is widely developed in the basin.Alluvial fan，fluvial，delta and lacustrine facies developed well during the Middle and Upper Triassic，and formed the key oil- and gas-bearing layers of the basin.According to the data collected from more than 100 drilling wells in the hinterland basin and many outcrops in the surrounding areas，as well as the long-term exploration and research experiences，we compiled 7 sedimentary facies maps of different oil-bearing intervals of the Middle-Upper Triassic Yanchang Formation of the Ordos Basin.The features of sedimentary facies in different depositional periods of the Yanchang Formation，especially the distribution and evolution of the dark mudstone and shale of the deltas and lacustrine facies，as well as the sand body of the various strand-bars and the gravity flow facies，were illustrated in detail.By the theoretical guidance of the sedimentary facies and lithofacies palaeogeography，the oil exploration of the Yanchang Formation has made great breakthrough constantly in the Ordos Basin.Several large oilfields，with the proved reserve more than 1×10 8 t，such as Shanbei，Xifeng，Jiyuan and Huaqing oilfields，have been discovered in recent years.

1 Research Institute of Exploration and Development,PetroChina Changqing Oilfield Company，Xi'an 710018，Shaanxi 2 National Engineering Laboratory for Exploration and Development of Low-permeability Oil & Gas Fields，Xi'an 710018，Shaanxi 3 Key Laboratory for Continental Dynamics of Ministry of Education，Northwest University，Xi'an 710069，Shaanxi

鄂尔多斯盆地位于中国的中西部，跨陕、甘、宁、蒙、晋5省区，盆地本部面积25万km 2 。中及上三叠统延长组在盆地内广为展布，厚逾千米，发育冲积扇、河流、三角洲、湖泊等沉积相，是该地区重要的油气产层。根据盆地腹地100多口井的钻井资料及盆地周边地区的露头资料，以及长庆油田长时期对延长组的油气勘探经验，编制出了鄂尔多斯盆地中及上三叠统延长组各油层组的沉积相图7幅，详细阐述了各油层组沉积时期的沉积相展布及演化，尤其是三角洲相、湖泊相以及其中的暗色泥岩和页岩、各种滩坝砂体及重力流砂体的展布及演化。在沉积相及岩相古地理理论的指导下，鄂尔多斯盆地延长组的油气勘探不断获得重大突破，相继发现了陕北、西峰、姬塬、华庆等亿吨级大油田。

... 邓秀芹等2010,2011a ...

2010

0.0

邓秀芹, 李文厚, 李士祥, 等. 2010. 鄂尔多斯盆地华庆油田延长组长6油层组深水沉积组合特征[J]. 地质科学, 45(3): 745-756.

Located in the depositional central of Ordos Basin in Late Triassic，the sedimentary of Chang 6 oil bearing formation in Huaqing area is characterized by mixed sources and deepwater deposition association which can be divided into three types，ie semideep lake and deep lake sediment，gravity current sediment and deepwater delta sediment. In different areas and stages，flow state will develop and transform one another. Delta sediment is featured by plentiful crossbeddings. Slump is marked by slide plan，with sudden lithologic contact relationship with overlying and underlying strata at top and bottom generally. Debrite in the study area is featured by development of different sized mud debris and turbidite presents normal grading. In the context of early lake regression，thick sandbody well developed in the central of Ordos Basin. Deposition controlled by northeast provenance is constitute of slump and progradation sand body of delta with thin layers of turbidite，and the deposition，controlled by southwest and west provenances，is constitute of turbidite，debrite and slump. In the mixedprovenance area，sediment is made up of debrite，turbidite and slump.

1.Key Laboratory for Continental Dynamics of the Ministry of Education, Department of Geology,Northwest University|Xian 710069； |2.Exploration and Development Research Institution of Changqing Oilfield Company|Xian 710018； |3.National Engineering Laboratory for Exploration and Development of  LowPermeability Oil &|Gas Fields|Xian 710018

华庆地区位于晚三叠世鄂尔多斯盆地湖盆沉积中心，长6油层组沉积复杂，具有多物源控制、深水沉积的特征。主要沉积类型可划分为半深湖—深湖沉积、重力流沉积及深水三角洲沉积。不同流态的流体在不同阶段和位置可以相互转化、相伴出现。在湖退背景下长6发育厚层砂体，成因复杂，主要包括深水三角洲砂体、滑塌砂体、砂质碎屑流砂体和浊积砂体等类型。其中三角洲砂体发育各种交错层理；滑塌砂体多顶底突变，发育滑动面；砂质碎屑流沉积颗粒大小混杂，含泥岩撕裂屑；浊积砂体通常为正粒序，或呈块状。从平面上分析，东北物源控制区主要为进积的三角洲砂体、滑塌砂体夹浊积砂体；西部、西南物源影响区主要为浊积砂体、滑塌和砂质碎屑流砂体；混源区和东北物源体系的前端主要为砂质碎屑流砂体、滑塌砂体和浊积砂体。

... 邓秀芹等2010,2011a ...

... 邓秀芹等,2010 ...

... 王家大庄为界,该线以东主要接受了东北物源的供给,该线以西主要受到西南和西部物源的影响(邓秀芹等,2010) ...

2008

0.0

邓秀芹, 蔺昉晓, 刘显阳, 等. 2008. 鄂尔多斯盆地三叠系延长组沉积演化及其与早印支运动关系的探讨[J]. 古地理学报, 10(2): 159-166.

The sedimentary characteristics of the lower part of the Yanchang Formation(Chang 10—Chang 8 oil bearing intervals)are quite different from the middle and upper parts of the Yanchang Formation(Chang 7—Chang 1 oil bearing intervals). During the deposition of the lower part of the Yanchang Formation，the western and southwestern areas of the basin were characterized by a gentle topography and the deposition was dominated by the braided fluvial，braided fluvial deltaic and coastalshallow lacustrine facies. The content of chemically unstable components was relatively higher in clastic rocks. The depositional framework changed greatly during the deposition of Chang 7 interval of the Yanchang Formation. The sedimentary systems changed to alluvial fan and fan delta in the west and southwest. The size of the downwarping depression increased quickly and semideep and deep lakes covered an area of over 10×10.4 km2. Simultaneously，the depocenter of the Ordos Basin was shifted tens of kilometers southwestwards. The component maturity of the clastic rocks increased and the rock combination was obviously different in the west and east dispersal tracts of sediments. Furthermore，analyses of the distribution of the tuffs in the Yanchang Formation indicate that the tuffs are steadily distributed in the basal part of Chang 7 interval of the Yanchang Formation and they were derived from the syndepositional volcanism. Their thickness decreased from the southwest to the northeast. These analyses indicate that the latest depositional period of Chang 8 interval of the Yanchang Formation is an important transitional stage in the basins sedimentary evolution. A strong tectonic movement occurred in the western margin and southwestern margin of the basin and volcanic activities took place frequently. These events represent the first episode of the Indosinian Movement.

Research Institute of Exploration and Development，PetroChina Changqing Oilfield Company，Xian710021，Shaanxi

鄂尔多斯盆地延长组下部（长8—长10油层组）沉积特征与中、上部（长1—长7油层组）存在较大的差异。延长组下部沉积时，盆地西部和西南地区地形相对较平坦，以辫状河、辫状河三角洲及滨浅湖沉积为主，碎屑岩中化学性质不稳定的组分含量较高；长7沉积期，沉积格局发生重大变革，盆地西缘、西南缘地区发育冲积扇、扇三角洲沉积体系，拗陷幅度急剧增大，半深湖—深湖区范围可达10×10.4 km2以上，而且湖盆中心向西南迁移了几十公里，碎屑岩成分成熟度增高，岩矿组合具有显著的东西分异性。此外，从延长组凝灰岩的分布特征分析，长7底部沉凝灰岩分布稳定，为同期火山作用的产物，厚度由盆地西南向东北方向逐渐减薄至不发育。上述分析表明，长8沉积末期为湖盆沉积演化的重要转折期，盆地西缘和西南缘存在一次强烈的构造地质事件，火山活动频繁，为印支运动第一幕重要的表现形式。

... 10⁴ km²,为中晚三叠世最大湖泛阶段,是该盆地烃源岩发育的主要时期(邓秀芹等,2008) ...

2011

0.0

... 8(邓秀芹等,2011b) ...

2012

0.0

付金华, 高振中, 牛小兵, 等. 2012 b. 鄂尔多斯盆地环县地区上三叠统延长组长6₃砂层组沉积微相特征及新认识[J]. 古地理学报, 14(6): 695-706.

There were 3 subfacies including delta-front，prodelta and deep lake，and 10 microfacies including underwater distributary channel，tributary bay，channel mouth bar，distal bar，prodelta clay，sandy debris flow，turbidity current，fluidized sediment flow，slump deposit and deep lake mud of the Upper Triassic Yanchang Formation Chang 6 3 interval in Huanxian area by detailed core observation，combined with logging data integrated analysis.A series of sedimentary microfacies profile maps and sedimentary microfacies distribution maps of Chang 6 3 interval show that delta-front subfacies developed in western，northern and northeastern part of the study area，deep lake subfacies including deep lake mud，sandy debris flow and turbidity current developed in central and southeastern part of the study area.The authors firstly proposed that sand sediments can transport from shallow water area to deep water area through a series of water channels on prodelta to form the gravity flow deposit.On the comprehension of above studies，the sedimentary model of study area was established. This paper finally analyses the hydrocarbon potential and points out that underwater distributary channel and sandy debris flow sedimentary microfacies are the best reservoirs in the study area.These sand bodies generally pinch out to form big lithological traps. The study area is the favorable lithologic reservoir exploration target zone.

1 Research Institute of Exploration and Development，PetroChina Changqing Oilfield Company，Xi′an 710018，Shaanxi;2 National Engineering Laboratory for Exploration and Development of Low-permeability Oil & Gas Field，Xi′an 710018，Shaanxi;3 School of Geosciences，Yangtze University，Jingzhou 434023，Hubei

通过岩心的详细观察，结合测井、录井资料综合分析，在环县地区上三叠统延长组长6 3 砂层组中，识别出了三角洲前缘、前三角洲和深湖3种亚相，和水下分流河道、支流间湾、河口砂坝、远砂坝、前三角洲泥、砂质碎屑流沉积、浊流沉积、液化流沉积、滑塌沉积和深湖泥10种微相。编绘了一系列沉积微相连井剖面图和长6 3 砂层组的沉积微相平面展布图，表明研究区西部、北部及东北部发育三角洲前缘亚相，研究区中部和东南部发育深湖亚相。在深湖亚相中除了深湖泥外，发育大量的砂质碎屑流和浊流等重力流沉积。作者首次提出了源于浅水区的砂级沉积物是通过前三角洲上的一系列水道搬运至深湖区形成重力流沉积的。综合以上研究成果，建立起了该区的沉积模式。论文最后分析了研究区的油气潜力，指出水下分流河道和砂质碎屑流沉积两种微相的储集性能最好。由于本区砂体横向尖灭现象普遍，可形成一些规模较大的岩性圈闭，是岩性油气藏勘探的有利目标区。

... 长1共10个油层组(付金华等,2005,2012a)(图1) ...

2005

0.0

付金华, 郭正权, 邓秀芹. 2005. 鄂尔多斯盆地西南地区上三叠统延长组沉积相及石油地质意义[J]. 古地理学报, 7(1): 34-44.

The Yanchang Formation of the Triassic in the Ordos Basin mainly developed two sedimentary systems: northeastern and southwestern systems. It has been proved that the northeastern sedimentary system belongs to the river delta system through abundant research data. However, the southwestern system is studied little due to the limitation of the exploration. Through the latest drilling and outcrop data, it has been established that the southwestern sedimentary system in the Ordos Basin belongs to the alluvial fan—fan delta system and the alluvial fan, fan delta and lake facies or turbidite facies were developed. The alluvial fan is representative in the sections of Pingliang Kongdongshan and Ruishuihe River. The fan delta and lake facies or turbidite facies are proved by the drilling sections in the study area. The main reservoirs include intervals Chang6 to Chang8 and the strata is preserved integratedly with the relatively high drilling degree. The subaqueous distributary channel is the main type of the fan delta front while the channel mouth bar is developed locally. The turbidite sandstone is mainly thick- bedded. Fan delta front subfacies was most developed during the Chang8 subage. Three delta front sand belts are formed from southwest to northeast and they are the important areas where hydrocarbon accumulates. The turbidite system was considerably developed in the Chang7 Subage because the lake basin subsided, the periphery was uplifted strongly and the lakeshore was very steep. The fan delta was developed again because the lake regressived during the Chang6 Subage, but the scale was smaller than that of the Chang8 Subage. The fan delta front sand body is the most advantageous zone of petroleum accumulation because its great thickness, coarse grain, well sorting and good physical properties.

1 Department of Geology, Northwest University, Xi’an 710069, Shaanxi 2 Research Institute of Petroleum Exploration and Development, Changqing Oilfield Company, PetroChina Xi’an 710021, Shaanxi

鄂尔多斯盆地三叠系延长组主要发育东北和西南两大沉积体系，东北的河流三角洲体系已为大量的勘探研究资料所证实，而西南体系因受勘探程度限制,目前研究不够。本文通过最新钻探成果，结合盆地西南部露头资料，确立盆地西南地区三叠系延长组为冲积扇-扇三角洲沉积体系，发育冲积扇、扇三角洲、湖泊（浊积）相。冲积扇以西南缘平凉崆峒山和汭水河剖面为代表，扇三角洲及湖泊（浊积）相为区内钻井剖面所证实。长6—长8为区内主力油层组，地层保存完整，钻探程度相对较高。扇三角洲前缘砂体类型以水下分流河道为主,局部发育河口坝,浊积体以厚层块状为主。长8亚期为扇三角洲前缘亚相最发育期，横向形成自西南向东北延伸的三支前缘砂体带，是石油聚集的重要区带；长7亚期随着湖盆沉降，周边抬升强烈，湖岸较陡，大量发育浊积体系；长6亚期湖退导致扇三角洲再次发育，但规模较长8亚期弱。扇三角洲前缘砂体单层厚度大,砂岩粒度较粗,颗粒分选及物性好,是石油富集的最有利相带。

... 进入21世纪,辫状河三角洲、湖盆中部富砂、多层系复合成藏等理论认识相继提出,有效地指导了西峰、华庆、姬塬大油田的快速探明(付金华等,2004,2005 ...

... 长1共10个油层组(付金华等,2005,2012a)(图1) ...

2012

0.0

付金华, 李士祥, 刘显阳, 等. 2012 a. 鄂尔多斯盆地上三叠统延长组长9油层组沉积相及其演化[J]. 古地理学报, 14(3): 269-284.

Delta and lacustrine sedimentary facies are recognized from the Chang 9 interval of the Upper Triassic Yanchang Formation in the Ordos Basin.The deltaic plain distributaries channel sandbodies and deltaic front subaqueous distributaries channel sandbodies are high quality reservoirs.Based on the research of sedimentary facies，according to the single factor analysis and multifactor comprehensive mapping method，the sedimentary facies distribution of the upper and lower parts of Chang 9 interval of Yanchang Formation in the Ordos Basin were studied and mapped.The single factors include strata thickness，content of deep water sedimentary rocks，sandstone thickness，sandstone strata thickness ratio，authigenic chlorite development characteristics，paleontology characteristics，sedimentary structure combination characteristics.Discussion was made about the sedimentary evolution rule of the Chang 9 interval.The results show that the Chang 9 interval of Yanchang Formation was characterized by the deposition of multiple delta sedimentary system which surround the lake and have multiple water systems and multiple provenances.The meandering fluvial deltas were mainly developed in the northeastern Ordos Basin，and the braided fluvial deltas were mainly developed in the western Ordos Basin.The deltaic plain distributaries channel microfacies and deltaic front subaqueous distributaries channel microfacies were well developed.During the depositional period of the lower part of Chang 9 of Yanchang Formation，semi-deep custrine was only developed in the center of the Ordos Basin.During the depositional period of the upper part of Chang 9 interval of Yanchang Formation，the custrine basin began to expanded，lake shoreline moved to the land，lake area enlarged，and the semi-deep custrine deposition greatly developed.From the lower part to the upper part of Chang 9 interval of Yanchang Formation，the water depth changed from shallow to deep.Correspondingly，a set of oil shale with hydrocarbon generating potential are deposited in the study area.

1 PetroChina Changqing Oilfield Company，Xi′an 710018，Shaanxi 2 Research Institute of Exploration and Development，PetroChina Changqing Oilfield Company，Xi′an 710018，Shaanxi 3 National Engineering Laboratory for Exploration and Development of Low-Permeability Oil & Gas Fields，Xi′an 710018，Shaanxi

鄂尔多斯盆地延长组长9油层组发育三角洲—湖泊沉积相，三角洲平原分流河道砂体和三角洲前缘水下分流河道砂体是最有利的储集砂体。在沉积相研究的基础上，根据单因素分析多因素综合作图法，选取了地层厚度、较深水沉积岩含量、砂岩厚度、砂地比、自生绿泥石分布、古生物化石分布和沉积构造分布等单因素，对鄂尔多斯盆地延长组长9油层组上下2段的沉积相平面展布特征进行了深入研究，并探讨了其演化规律。研究表明，鄂尔多斯盆地以发育多水系、多物源注入的环湖分布的多个三角洲为特色，东北部地区主要发育曲流河三角洲，西部发育辫状河三角洲，其中以三角洲平原分流河道和三角洲前缘水下分流河道微相较为发育。长9 2 沉积期，半深湖沉积在盆地内较为局限，长9 1 沉积期湖盆初始扩张达到最大范围，湖岸线向陆推移，湖域面积扩大，半深湖沉积较发育。由长9 2 沉积期到长9 1 沉积期，鄂尔多斯盆地沉积水体经历了由浅变深的过程，由此在长9 2 的顶部沉积了一套具有生烃潜力的油页岩。

... 付金华等,2012b ...

2004

0.0

2012

0.0

1986

0.0

... 90年代在三角洲成藏理论的指导下发现了安塞、志靖岩性油藏(李克勤,1986) ...

2011

0.0

李相博, 付金华, 陈启林, 等. 2011. 砂质碎屑流概念及其在鄂尔多斯盆地延长组深水沉积研究中的应用[J]. 地球科学进展, 26(3): 286-295.

Sandy debris flow is a new sandy type and attracts more and more attention in recent years. Its relative theory is partial negation and improvement of deepwater sediments concepts like the "Bouma Sequence" and "turbidite fan". This paper describes the essence of the concept of sandy debris flow and existing problems, and points out that only by combining the features of continental sedimentary basins in China to improve the theory can the success rate of exploration be improved, thereby promoting the development of China's oil industry. This paper also used the concept of sandy debris flow. The sedimentation of Chang 6 is divided into sandy debris flow, classic turbidite and slump, the three kinds of sediment gravity flows and traction underflow in the deep water area of the lake center in Ordos Basin. Studies suggest that sandy debris flow most develops in the region, and its spatial distribution is mainly controlled by the deepwater slope breaks. Steep and gentle slope significantly have different distribution patterns; the former generally parallels to the slope break distribution, and the latter distribution is perpendicular to the slope break. Finally, the paper points out that because of the wide area of distribution, large thickness and good hydrocarbon accumulation conditions, sandy debris flow is one of the most advantageous and new exploration areas in the future in Ordos Basin.

1.Northwest Branch,PetroChina Exploration and Development Research Institute,Lanzhou730020, China； 2.Exploration and Development Institute of PetroChina Changqing Oilfield Company，Xi′an710018,China; 3.Ordos Branch, PetroChina Exploration and Development Research Institute,Beijing100083, China

砂质碎屑流是近年来日益受到重视的一种新的砂体成因类型，其相关理论是对“鲍玛序列”和“浊积扇”等深水沉积理论的部分否定和完善。阐述了砂质碎屑流概念精华与存在问题，指出只有进一步结合我国陆相盆地沉积不断完善该理论,才能提高勘探成功率，从而促进我国石油工业的发展。同时运用砂质碎屑概念，将鄂尔多斯盆地湖盆中心深水区延长组长6段沉积划分为砂质碎屑流、经典浊积岩和滑塌岩3种沉积物重力流及牵引底流等。研究认为砂质碎屑流在该地区最为发育，其空间分布主要受深水坡折带控制，且陡坡与缓坡分布模式明显不同，前者大致平行于坡折带分布，后者垂直于坡折带分布。最后指出，由于砂质碎屑流分布面积广，厚度大，成藏条件优越，是鄂尔多斯盆地今后最为有利的勘探新领域之一。

... 李相博等,2011 ...

2013

0.0

... 廖纪佳,2013) ...

2012

0.0

田景春, 王文之, 王峰, 等. 2012. 鄂尔多斯盆地华池—庆阳地区上三叠统延长组长6油层组古地震变形构造及砂体叠置关系[J]. 古地理学报, 14(3): 269-284.

... 延长组长6、长7油层组沉积物中记录了大量的凝灰岩薄层、砂岩岩脉(图 3-d)、包卷层理、砂泥搅浑构造(图 3-e)、阶梯状微断层(图 3-f)、枕状构造(图 3-g)等,指示了较动荡的构造环境(田景春等,2012) ...

2005

0.0

... 1%,进入生排烃高峰阶段,具有高产烃率(产油率达400 kg/t)、高排烃效率(一般为55%~90%)(杨华等,2005)、广覆式生烃的特征 ...

2012

0.0

... 杨华等,2012,2013),石油勘探进入大发展阶段,实现了由盆地周边三角洲找油向湖盆中部深水砂岩找油的转化,勘探层系由浅层向深层的转移,勘探对象由常规油藏到低渗透油藏再到非常规致密油的转变 ...

2013

0.0

... 杨华等,2013 ...

... 但目前对致密储集体的物性尚无统一的标准,杨华等(2013)提出致密储集层孔隙度小于10%,基质负压渗透率小于0 ...

2012

0.0

... 近几年来,深水砂岩和非常规油气资源的研究引起了极大的关注(姚泾利等,2012 ...

2007

0.0

姚泾利, 王克, 宋江海, 等. 2007. 鄂尔多斯盆地姬塬地区延长组石油运聚规律研究[J]. 岩性油气藏, 19(3): 32-37.

Based on the analysis of source rocks , reservoir , dynamics and migration pat hways of Yanchang Formation in J iyuan area , Ordos Basin , the rule of pet roleum migration and accumulation is analyzed. Dark mudstones were developed in t he maximum lake flooding period of Chang 7 , which are t he main source rocks. Most of t he reservoir s are ext ra2low permeability reservoir s. The intergranular pore is t he main space for reservoir , and t he pore throat types are mainly t hin2pore wit h micro2throat and micro2pore with micro2t hroat . Anomalous pressure is t he main dynamic for t he hydrocarbon migration , and it is closely related to t he dept h of t he duck mudstone. Connected sand bodies are t he main migration pat hway , in which high permeability in accumulation stage takes an important part . The reservoir dist ribution of Yan-chang Formation is partly cont rolled by micro2f ractures. Two types of accumulation patterns including “source rocks - connected sand bodies - reservoir”and“source rocks - micro2f ractures - reservoir”are finally summarized.

1. School of sedimentary , Cheng du Uni versi t y of Technology , Cheng du 610059 , China; 2. Research I nsti tute of Pet roleum Ex ploration and Development , Changqing Oi l f iel d Company , Pet roChina , X i’an 710021 , China

在分析鄂尔多斯盆地姬塬地区延长组烃源岩、储集层特征、运移动力学特征和运移通道特征等成藏主控因素的基础上,总结了延长组低渗储层的石油运聚规律。延长组长7 段最大湖泛期发育一套暗色泥岩,干酪根类型为腐植2腐泥型,是盆地主要生油岩。储层以低渗透为主要特征,绝大部分属于超低、特低渗储层,储集空间以残余粒间孔为主,孔喉类型以细孔微喉型和微孔微喉型为主。异常高压是石油运移的主要动力,长7 段异常压力的分布与暗色泥岩的厚度有关,在暗色泥岩厚度大的区域,异常压力较大。连通砂体是石油运移的主要通道,成藏期储层相对高渗透是连通砂体成为有效运移通道的基础。微裂缝控制了局部地区延长组油藏的分布及其规模。通过对该盆地的分析,总结出了2 类成藏模式,即“源岩2连通砂体2储层”连续式充注成藏模式和“源岩2微裂缝2 储层”幕式充注成藏模式。

... 姚泾利等,2007,2011 ...

2011

0.0

姚泾利, 王琪, 张瑞, 等. 2011. 鄂尔多斯盆地华庆地区延长组长6砂岩绿泥石膜的形成机理及其环境指示意义[J]. 沉积学报, 29(1): 72-79.

〓With thin section analysis and scanning electron microscopic analysis, the diagenetic phenomenon of Yanchan Formation sandstone in the Ordos basin were systematically studied, and it shows that chlorite film was the important diagenetic phenomenon in this area. Depending on the studies relevant to the features including occurrence, structural characteristics, relations between other diagenetic minerals of sandstones in this area, the formation mechanism was discussed in detail. Chlorite rim had some relevance with the original porosity of reservoirs, its formation had more closely relationship with hydrodynamic conditions during the contemporaneous deposition. They belonged to a mark of water power conditions for they occur mainly in the subaqueous distributary channel and mouth bar in the deltaic front, and had strong environmental specificity; chlorite rim had double layer structure in which isopachous rim cement of internal layer was relative dense, and formed during the early diagenetic stage. Outerlayer authigenic chlorite grown on the rim surface vertically with better crystal form was formed during the late diagenetic stage; chlorite film was of a limited ability to protect the sandstone porosity. The reason for this is that the porosity of sandstones with chlorite clay rim was better mainly depended on the petrological characteristics of sedimentary sandstones under strong hydrodynamic condition. It had little relation with the chlorite clay rim. So the formation model of chlorite clay rim was put forward. It was considered that the formation of the chlorite film experienced five steps: sedimentary stage of original particles, stage of clay adsorption and film formation on the surface of original particles, early compaction stage of particles, stage of rim chloritization, authigenic chlorite forming stage; In view of this, the sedimentary sandstone reservoirs that had chlorite clay rims under strong hydrodynamic conditions should be the target in the process of oil exploration. 

Research Institute of Exploration and Development, PetroChina Changqing Oilfield Company, Xi'an 710021

通过薄片鉴定和扫描电镜等技术手段，对鄂尔多斯盆地延长组砂岩的成岩现象进行了分析，发现绿泥石黏土膜为该区重要的成岩现象。在对该区砂岩绿泥石黏土膜的产状、结构特征及与其它成岩矿物之间的关系等特征分析的基础上，对其形成机理进行了详细讨论，认为绿泥石黏土膜与储层原生孔隙具有一定的关联作用，其形成与同沉积时期水动力条件关系更为密切，属于强水动力沉积条件的一种标志，主要发育于三角洲前缘水下分流河道和河口坝等微相中，具有较强的环境专属性；绿泥石黏土膜具有双层结构，里层的等厚环边胶结物相对致密，是早期成岩阶段形成的。外层的自生绿泥石垂直于环边表层生长，晶形较好，是晚期成岩阶段形成的；绿泥石黏土膜保护砂岩孔隙能力有限。绿泥石黏土膜发育的砂体物性较好，主要是由于强水动力条件下沉积的砂体本身岩石学特性所决定，与绿泥石黏土膜关系不大。由此提出绿泥石黏土膜形成模式，认为其形成经历了5个阶段：原始颗粒沉积阶段、原始颗粒表面黏土吸附成膜阶段、颗粒初期压实阶段、环边绿泥石化阶段和自生绿泥石形成阶段。鉴于此，在华庆地区延长组石油勘探过程中，应寻找绿泥石黏土膜相对发育的强水动力条件下的沉积砂岩储集体。

... 姚泾利等,2007,2011 ...

2001

0.0

... 张国伟等,2001),另一方面对其南北两侧分布的盆地演化产生了重要的影响 ...

2013

0.0

... 邹才能等,2013),并取得了重要的勘探成果,成为鄂尔多斯盆地石油勘探最主要的目标之一,有力地推动了长庆油田储量和产量的快速增长 ...

1962

0.0

... 自上世纪50年代以来,许多古代和现代的深水砂岩被发现和报道,并以鲍马序列作为识别浊积岩的标准(Bouma,1962,2000),使得长期以来大部分深水砂岩被解释为浊积岩,并且就浊积岩和浊积相的划分开展了大量的研究(Morris,1971 ...

2000

0.0

2000

0.0

... Hacker et al ...

1982

0.0

... Lowe,1982 ...

1985

0.0

... 大别褶皱带(Mattauer et al ...

1971

0.0

1992

0.0

... Mutti,1992) ...

1986

0.0

... Pikering et al ...

2000

0.0

... 但Shamugam(2000,2003)从过程沉积学的角度明确指出鲍马序列的沙纹层理、平行层理等段具有牵引流的特征,严格意义上不是重力流,更不是浊积岩 ...

2003

0.0

... 但Shamugam(2000,2003)从过程沉积学的角度明确指出鲍马序列的沙纹层理、平行层理等段具有牵引流的特征,严格意义上不是重力流,更不是浊积岩 ...