珠江口盆地白云凹陷北坡珠江组沉积特征及其控制因素分析

发布时间：2018-04-21 18:46

本文选题：白云凹陷 + 珠江组　；参考：《中国地质大学》2017年硕士论文

【摘要】：南海北部是我国油气勘探的重要区域,随着勘探程度的加深,浅海陆架已经难以满足日益增加的油气需求,向深海过渡区发育的陆架边缘三角洲和盆底扇等大型储集层受到越来越多的关注。珠江口盆地白云凹陷北坡陆架陆坡区由于存在大型三角洲和盆底扇储集体成为油气勘探的热点领域。本文应用最新的覆盖全区的三维地震、钻井及测井资料,以盆地构造分析、层序地层学、沉积体系分析和地震沉积学为理论指导,重点应用“点、线、面、体、时”的综合分析的思路开展研究工作,在确定了白云凹陷北坡珠江组坡折类型、展布规律的基础上,构建了白云凹陷北坡珠江组高精度构造-层序地层格架,进而开展沉积体系分析工作,确定层序构成、沉积体系的时空配置关系,并通过同沉积期构造古地貌恢复,确定陆架坡折对沉积体的控制,最终揭示等时格架内沉积相带与构造坡折带或构造古地形、物源供给体系等的内在联系,阐明体系域空间差异性分布的主控因素,建立了沉积体系时空演化模式,为该区油气勘探的全面深入提供坚实的地质依据。研究取得的主要成果及认识如下:1、基于最新的三维地震及钻测井资料,确定了白云凹陷北坡珠江组为多阶断裂坡折,并阐明了其空间展布。研究区珠江组一段(23.8Ma-21Ma)层序内陆架坡折位于研究区东南部。珠江组二段(21Ma-17.5Ma)时期内,由于白云运动基底沉降结束,陆架坡折北迁到番禺低隆起区域,且为多阶断裂坡折。除了陆架坡折,在陆坡区将两条雁列式断裂带划分为一阶坡折和二阶坡折。这样陆架坡折、一阶坡折及二级坡折一起将研究区划分为陆架区、上陆坡区、下陆坡区及深海平原区。陆架坡折带制约着盆地充填可容纳空间的变化,从而影响研究区沉积体系的分布。2、识别了白云凹陷北坡珠江组发育层序界面、查明了各反射界面特征,构建了高精度层序地层格架,阐明了层序构成样式。对研究区内17口单井层序地层、多条连井及覆盖全区的三维地震剖面的综合追踪分析比对的基础上,识别出珠江组SB23.8、SB21和SB17.5等三个层序界面,据此将珠江组划分为两个三级层序(珠江组一段和珠江组二段);在珠江组二段(SB21-SB17.5)内还识别出FFS(初始海泛面)和MFS18.5(最大海泛面),将珠江组二段划分为低位、海侵和高位体系域。构建了坡折控制下的层序发育模式,具体表现为珠江组一段在研究区只发育高位体系域,东南发育的坡折控制斜坡扇的发育;珠江组二段上陆坡区发育三角洲沉积,一阶坡折控制下陆坡区发育斜坡扇沉积,二阶坡折控制深海平原的盆底扇沉积。3、查明了白云凹陷北坡珠江组沉积体系时空展布特征,建立了陆架边缘三角洲和多分支水道化扇等两类沉积模式。运用岩芯柱状图、单井连井剖面图、地震属性图综合分析并相互校正,建立体系域空间沉积体系的时空演化模式。研究表明,陆架边缘三角洲沉积体系以西部特征最为典型,主要发育有陆架边缘三角洲—多分支水道化扇—盆底扇等沉积体的转化;受控于陆架坡折陆架边缘三角洲主要来自北部点状物源,一阶坡折的控制下陆架边缘三角洲二次搬运形成多分支水道化扇,二阶坡折控制下多分支水道化扇三级搬运形成下部的盆底扇;多分支水道化扇沉积体系以东部发育典型,发育陆架三角洲—陆架砂—斜坡水道—多分支水道化扇—盆地扇及灰质水道等沉积体的转化,陆架边缘三角洲为来自东北的线物源其受控于陆架坡折的发育,在一阶坡折的控制下,通过高角度斜坡水道二次搬运形成宽缓且大面积扇体展布的多分支水道化扇沉积,多分支水道化扇在二阶坡折的控制下,通过三次搬运形成进入深海平原的盆底扇沉积。4、揭示了白云凹陷北坡珠江组沉积体空间展布的主控因素:构造作用、古地貌、物源供给。(1)构造活动,研究区23.8-21Ma属于断陷期,同沉积断裂活动全区比较剧烈,活动指数普遍较高;21-17.5Ma期间,全区范围内断裂活动明显减弱,但少数断裂持续活动的区域构造背景下,长期活动的同沉积断裂形成的“多阶构造坡折带”制约着盆地充填可容纳空间的变化;(2)古地貌,古地貌控制着低位体系域的砂分散体系和相分异,珠江组一段时期,古地貌的起伏主要控制东南部的斜坡扇沉积;珠江组二段时期,古地貌起伏增强,在研究区北部形成陆架坡折,控制西部来自西北物源、东部来自东沙和东北物源的陆架边缘三角洲、一阶坡折控制二次搬运的多分支水道化扇和二阶坡折控制三次搬运的盆底扇。且西部坡度明显小于东部坡度,使东部更多的三角洲“背景源”沉积物通过斜坡水道搬运到下陆坡区沉积,使东部多分支水道化扇和盆底扇的规模和展布范围较西部大。(3)物源供给,西部主要为北部点源富砂充填,仅在河道流经区域砂体含量高,东部为多点-线源富砂充填,整个区域砂体含量相当。
[Abstract]:The northern South China Sea is an important area for oil and gas exploration in China. With the deepening of the exploration degree, the shallow sea shelf has been difficult to meet the increasing demand for oil and gas. The large reservoirs, such as the continental shelf margin Delta and the pelvic floor fan developed into the deep sea transition area, have attracted more and more attention. Large delta and pelvic floor fan reservoirs have become the hot areas of oil and gas exploration. In this paper, the latest three dimensional earthquake, drilling and logging data covering the whole area are guided by the theory of basin structure analysis, sequence stratigraphy, sedimentary system analysis and seismic sedimentology, and the comprehensive analysis of "point, line, surface, body and time" should be focused on. On the basis of determining the type of slope break of the Pearl River group in the north slope of Baiyun Sag, the high precision tectonic sequence stratigraphic framework of the Pearl River Group on the north slope of Baiyun sag is constructed, and then the analysis work of the sedimentary system is carried out, the sequence composition, the spatio-temporal disposition relation of the sedimentary system are determined, and the paleogeomorphology of the sedimentary period is restored, In order to determine the control of the continental shelf break to the sedimentary bodies, the internal relations between the sedimentary facies in the isochronous frame and the tectonic slope fold belt or the tectonic paleotopography and the source supply system are revealed, and the main controlling factors of the spatial difference distribution in the system domain are clarified, and the spatio-temporal evolution model of the depositional system has been set up to provide a solid ground for the comprehensive and thorough exploration of the oil and gas in this area. The main achievements and understanding of the research are as follows: 1, based on the latest 3D seismic and drilling and logging data, the Pearl River group in the north slope of Baiyun sag is a multi-step fracture slope, and its spatial distribution is clarified. The slope fold of the Pearl River group A (23.8Ma-21Ma) sequence in the study area is located in the southeast of the study area. The two section of the Pearl River group (21Ma-17.5Ma) During the period, due to the end of the basement subsidence of the Baiyun movement, the continental shelf slope breaks north to the Panyu low uplift area and is a multistage fracture slope. In addition to the continental slope break, the two echelon fault zones are divided into one order slope break and two order slope break in the Continental slope area, so that the shelf break, the first slope break and the two grade break together divide the study area into the continental shelf area, and the uplift area is divided into the continental shelf area. The slope zone, the land slope area and the deep sea plain area. The continental slope folding zone restricts the changes in the accommodating space of the basin filling, thus affects the distribution of the sedimentary system in the study area.2, identifies the sequence boundary of the Pearl River Formation in the north slope of Baiyun Sag, and finds out the characteristics of the reflection interface, and constructs a high degree sequence stratigraphic framework and clarifies the sequence pattern. On the basis of 17 single well sequence stratigraphy, multiple wells and the comprehensive tracking and comparison of the three dimensional seismic profiles in the whole area, three sequence interfaces of SB23.8, SB21 and SB17.5 in the Pearl River formation are identified. According to this, the Pearl River group is divided into two three order sequences (Pearl River group one and Pearl River group two), and in the two segment of the Pearl River group (SB21-SB17.5) FFS (initial sea pan surface) and MFS18.5 (the most sea surface) are identified, and the two segments of the Pearl River group are divided into low position, transgression and high system domain. The sequence development model under the control of slope break is constructed. The development of the Pearl River group a section in the study area is only developed in the study area, the development of the slope folds in the southeast is controlled, and the two section of the Pearl River group is on the land. Delta deposits in the slope area are developed, the slope fan deposits are developed under the control of the first order slope, and the two order slope break control the pelvic floor fan in the deep sea plain to deposit.3, and find out the spatial and temporal distribution characteristics of the sedimentary system of the Pearl River Group on the North Slope of Baiyun Sag, and set up two types of depositional modes, such as the Delta and the multi branch channel fan, in the north slope of the Baiyun sag. It is shown that the continental shelf marginal deltaic depositional system is the most typical of the western characteristics of the continental shelf, and mainly developed on the continental shelf margin Delta, the multi branch channel and the pelvic floor fan, and controlled by land. The marginal delta of the shelf is mainly from the northern point source, and the first step of the slope break control is to form a multi branch channel fan, and the multi branch channel fan is transported by three stages under the control of the two order slope to form the lower part of the pelvic floor fan, and the multi branch channel fan sedimentation system is typical in the eastern development and develops the continental shelf triangle. The continental shelf sand, the slope channel, the multi branch channel fan, the basin fan and the gray matter channel, etc., the continental shelf fringe delta is controlled by the continental shelf break from the northeast. Under the control of the first order slope break, two times through the high angle slope channel are transported to form the wide and large area fan body distribution. Under the control of the two order slope break, the multi branch channel fan deposited.4 in the pelvic floor fan which entered the deep sea plain under the control of the two order slope break. It revealed the main controlling factors of the spatial distribution of the sedimentary bodies of the Pearl River Formation in the north slope of the Baiyun sag: tectonic action, palaeogomorphology, source supply. (1) tectonic activity, and the 23.8-21Ma in the study area belongs to the period of the fault depression and the same subsidence. The activity index is relatively high and the activity index is generally high; during 21-17.5Ma, the fault activity in the whole area is obviously weakened, but under the regional tectonic setting of the continuous activity of a few faults, the "multi order tectonic slope belt" formed by the long-term active synsedimentary fault restricts the change of space in the basin filling; (2) paleogeomorphology and ancient land The appearance controls the sand dispersion system and phase differentiation in the low system domain. During the first period of the Pearl River group, the palaeogomorphic relief mainly controlled the slope fan deposits in the southeast, the two period of the Pearl River group, the palaeogomorphic relief increased, the continental shelf break was formed in the northern part of the study area, the Western source was controlled from the northwest and the east of the east from the East Sand and the northeast. The first order slope break control the multi branch channel fan and the two order slope to control the three times of the pelvic floor fan, and the western slope is obviously less than the eastern slope, so that more Delta "background source" sediments in the East are transported to the lower slope through the slope channel, and the scale of the multi branch channel fan and the pelvic floor fan in the East will be made in the East. And the range of distribution is larger than that in the West. (3) the supply of material source in the west is mainly sand rich filling in the north point source. Only in the river, the sand body content is high, the East is multi point - line source rich sand filling, the whole area sand body content is equal.

【学位授予单位】：中国地质大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：P618.13

【参考文献】