【作者】 董福湘；

【导师】 刘立；

【作者基本信息】 吉林大学 ， 矿物学、岩石学、矿床学， 2004， 博士

【摘要】 前人对扇三角洲和辫状河三角洲的研究注重井下砂体解剖和露头剖面的观察，并且从岩相、测井相和地震相入手，系统地研究了扇三角洲和辫状河三角洲沉积特征。然而，通过地震等方法查明的构造现象实际上都经历了多次构造运动的改造，不能代表其原始状态。许多研究者虽致力于研究恢复古构造的方法，并据此探索古构造对沉积的控制，但这些研究主要侧重于古构造对油气运移、聚集的驱动和封存的控制作用。唯独古构造对扇三角洲或辫状河三角洲这一单一沉积体系的控制的研究比较薄弱。十屋断陷位于松辽盆地东南隆起区东南缘，长春-四平一线西北，长岭-双辽一线东南，其东北是德惠断陷，西南为柳条断陷，面积约 1600km2。十屋断陷是晚侏罗世以来发育而成的、由 NNE 向的弧型西边界断层所控制的箕状断陷，断陷内断裂十分发育，根据断层规模及其在盆地演化中的作用将其分为基底主干断层、基底次级断层和盖层断层。断陷的基底和盖层可划分为断陷前基底层序、同断陷层序和断陷后坳陷层序等三套构造层序，同断陷层序中的沙河子组、营城组为本文的研究对象。具体研究内容及得到的认识如下：通过对有关扇三角洲和辫状河三角洲理论基础的综述，认为十屋箕状断陷深部领域的西侧陡坡，由于断裂活动强烈，物源供给充足，常发育沉积厚度大、相带窄、相变快、岩性粗而杂的扇三角洲沉积体系。北部斜坡、东部缓坡发育辫状河三角洲沉积，由于被断裂错开的地层上升量、物源供给相对少些，因此，沉积厚度较薄，平原相带和滨岸过渡带较宽，但前缘相带较窄，入水后较快变为开阔湖沉积。扇三角洲和辫状河三角洲的主要区别表现在三角洲的平原部分。根据岩芯观察、测井资料分析、结合地震解释，在十屋断陷深部领域主要识别出 15种岩石相类型，将其划分出 7 种岩相组合即：辫状河道微相、辫状分流河道微相、水下水道微相、前缘砂微相、边缘席状砂微相、开阔湖沉积微相和水下重力流沉积微相。并且，从测井曲线和地震等多个角度详细研究了十屋断陷的扇三角洲体系和辫状河三角洲的沉积微相特征。齿化箱形和中高幅齿状漏斗形、齿状漏斗形—箱形组合的测井曲线分别是识别辫状河道沉积和扇三角洲前缘沉积亚相的主要测井相类型；扇三角洲纵向几何形态一般呈楔状，内部反射结构多表现为杂乱状、乱岗状或无反射特征，中部至端部反射为斜交前积连续性相对较差，振幅变化大是在地震剖面上识别扇三角洲的主要特征。横剖面上一般为丘状；滨浅湖相、深湖-半深湖相的岩性以泥岩夹粉砂岩为特征，自然电位曲线分别为 1<WP=118>低幅齿形和微齿平直形；浊积岩相测井曲线表现为高幅锯齿状或指状；辫状河三角洲平原自然电位曲线呈箱状，地震剖面上，沉积物前积方向可见斜交和迭瓦状前积结构。 通过高分辫率层序地层学方法与层序地层学方法，结合地震手段，将十屋断陷深部领域的沙河子组和营城组划分为两个层序，分别相当于 Vail 的Ⅲ级层序，每个层序划分为低水位、湖进和高水位体系域。在对单钻进行高分辫率层序地层划分的基础上，建立起同一辫状河三角洲的层序地层格架和扇三角洲—辫状河三角洲的层序地层格架及八屋地区地震剖面的层序地层格架。结果表明，低水位期扇三角洲沉积体的根部和中部沉积相单一，而端部沉积相类型多、旋回性强，湖进期无论扇体根部、中部和端部，都表现为深湖、半深湖沉积与扇三角洲沉积相互叠置、交替发育。 八屋地区辫状河三角洲体系及其它沉积体系的平面分布研究表明，沙河子层序在低水位期，以滨浅湖为主，半深湖—深湖分布局限，北部为冲泛平原，在冲积体系入湖处，形成两个辫状河三角洲。在湖进期，湖区面积扩大，深湖—半深湖区连片，冲泛平原减少，东部辫状河三角洲仍然存在，在南部新形成一个辫状河三角洲。在高水位期，滨浅湖分布范围略有扩大，在研究区的中部形成一水下扇体，湖进期形成的辫状河三角洲依然存在；营城层序在低水位期，主要发育冲积体系、湖泊沉积体系和辫状河三角洲沉积以及洪泛沼泽。在湖进期，湖区面积扩大，冲积体系缩小，辫状河三角洲仍保持发育，冲积体系内部湿地发育、沼泽连片。在高水位期，湖泊沉积体系进一步缩小，冲积体系的分布范围保持不变。在湖泊体系与冲积体系的过渡处，沼泽呈带状分布，辫状河三角洲分布面积缩小。 利用现今三维地震联片构造图采用剖面法恢复十屋断陷沙河子和营城时期沉积时的古构造，得出不同时期主要沉积界面的古构造图，古构造的研究结果表明，基底界面、营城层序底界面的古地貌和古断层与现今不同。基底界面从 T4 时期到 T4、T3时期乃至现今 1的总体变化规律为，由基岩凸起分隔的三个主要沉降区，发展为由 F6和 F5基底断裂及其形成的基岩凸起分隔的两个主要沉降区，其中，十屋东沉降区不断东扩，而大刘家屯沉降区由受多个基底断裂控制的不规则形状沉降区发展为主要受 F6和 F5基底断裂控制的狭长状沉降区，最后演变为西陡东缓的构造格局，并且，现今时期的基底界面多发育了 SN 向小型正断层；营城组底界面的变化规律为，T4 时期?更多还原

【Abstract】 As to fan-delta and braided river-delta the formers emphasize on dissecting sandstoneunderground and observing outcrop profile and have studied systematically sedimentarycharacteristic of fan-delta and braided river-delta according to lithofacies, well-logging faciesand seismic facies. In fact, the structure phenomena clarified by means of seism have sufferedalteration for several times, so they are not to represent primary situation. Despite manyinvestigators commit themselves to finding more means of reconstructing paleostructure toexplore controlling of paleostructure to sediment, they focus on the control action ofpaleostructure to driving and sealing of oil and gas migration and accumulation. The control ofpaleostructure to fan-delta and braided river-delta, adopted in this study, is relatively fewerinvolved. Shiwu faulted basin, about 1600km2, northeast of which is Dehui faulted basin, southwestof which is Liutiao faulted basin, lies in southeast of southeast uplift area in Songliao Basin,north west of the line of Changchun-Siping, southeast of the line of Changling-Shuangliao.Shiwu faulted basin is a dustpan-like basin controlled by arc-shaped west borderline trendingNNE, forming since late Jurassic. There are many faults in the faulted basin which are classifiedinto basal main faults, basal sublevel faults and cover faults according to scale and the action offaults in the basin evolvement. The base and cover can be divided into such three sets ofstructural successions as pre-faulted basal succession, sync-faulted succession and depressionsuccession after faulting. The research target of the paper is Shahezi and Yingcheng Formationof sync-faulted succession. The contents and results obtained are such follows. In terms of fan-delta theory domestic and abroad, it is believed that at the west slope ofShiwu faulted basin fan-delta with great thickness, narrow phase belt, quick phase change andcoarse or mixed lithologic characters developed because of strong activity of faults and enoughsource supplied. However, at the north slope and east gentle slope, braided river-delta developedas stratum ascending and source are both few. Therefore, the sedimentary thickness is small andplain facies belt and coastal transition is wide while delta front, turning to wide lacustrine facieswhen entering water, is narrow. The main difference of fan-delta and braided river-delta consistsin delta plain. 4<WP=121>By means of core observation, logging analysis and seismic interpretation, 15 types oflithofacies are identified and 7 lithologic assemblages is divided, namely braided channelmicrofacies, brainded branch channel microfacies, underwater channel microfacies, delta frontsand microfacies, fringe sheet sand microfacies, wide lacustrine microfacies and underwatergravity current microfacies. In addition, sedimentary microfacies characteristics of fan-delta andbraided river-delta are studied in detail in term of logging, seism etc. Sawtooth box-like logging and mid-high breadth sawtooth funnel-like, sawtooth funnel-like—box-like logging are main logging facies types used to respectively recognize braided channeland fan-delta front. In longitudinal direction geometrical shape of fan-delta is like wedge, andinner reflection configuration represents disorder or non-reflection, from middle to end thereflection, with poor continuity, behaves as oblique crossing foreset. So the variety of amplitudeis main character of recognizing fan-delta from seismic profile. In horizontal profile reflection ofseismic seems hillock. The lithologic characters of coastal and offshore lake facies,deep-middeep lake facies is mainly mudstone and siltstone. Spontaneous-potential loggingappears as low breadth sawtooth-like and tiny sawtooth flat. Turbidite is part of prodelta, loggingof which appears as high breadth sawtooth or finger-like. Spontaneous-potential logging ofbraided river delta plain appears like b更多还原