梨树断陷北部斜坡带下白垩统营城组二段沉积体系研究

发布时间：2018-02-02 17:19

  本文关键词： 梨树断陷 北部斜坡带 沉积体系 营城组二段　出处：《中国地质大学(北京)》2017年硕士论文　论文类型：学位论文

【摘要】：营城组是梨树断陷北部斜坡带的主力油层,前人已对该区营城组构造演化、烃源岩分布、层序地层划分等做了大量研究工作,并取得丰硕成果。但在营二段物源及沉积体系等方面研究程度较低,这极大地制约了该区的油气勘探与开发。本文通过岩芯观察、钻测井数据分析和三维地震资料解释处理等方式,对营二段物源体系分布和沉积微相展布特征进行详细研究。将营二段划分为SG1、SG2和SG3三个砂层组。其中SG1砂组砂岩含量较高,颗粒较粗,砂体叠置方式以进积为主;SG2砂组砂岩粒度较细,以泥岩夹砂岩沉积为主,且泥岩颜色深,砂体叠加方式以退积-加积为主;SG3砂组砂岩颗粒变粗,砂体表现为进积叠置方式。综合来看,北部斜坡带营二段各砂层组地层厚度均呈现出“东薄西厚、北薄南厚”的特点,推测沉积中心位于研究区西南部。通过对重矿物、砾岩含量以及泥岩颜色分布特征综合分析发现,营二段不同时期物源方向略有不同:SG1砂组物源主要来自盆地北部和北西部;SG2砂组受北部物源影响较大;SG3砂组则主要受北部和东部物源的作用。在研究区内共识别出以下六种沉积微相:辫状河三角洲前缘水下分流河道、河口坝、水下分流间湾、滨浅湖滩坝、砂泥坪和滨浅湖泥。营二段主要发育在水体较浅环境中,除去广泛分布的滨浅湖泥质沉积之外,SG1砂组水下分流河道和河口坝微相发育;SG2砂组沉积时期湖盆范围增大,以滨浅湖亚相沉积为主,常见滩坝微相沉积;SG3砂组主要发育辫状河三角洲前缘河口坝和水下分流间湾微相。综合物源体系分布和沉积相展布特点,明确了研究区营二段各砂层组沉积时期的沉积演化特征。SG1时期,湖水深度浅,北部辫状河三角洲前缘砂体广泛分布,并向南进积;SG2时期,湖盆水体范围扩大,北部辫状河三角洲前缘砂体向北后退,展布范围相对减小,研究区南部大面积发育滨浅湖泥质沉积;SG3砂组沉积时期,湖平面有所下降,辫状河三角洲前缘砂体在北部呈带状分布特征。纵向上,辫状河三角洲前缘砂体发育具有继承性和弱旋回性的特征。
[Abstract]:Yingcheng formation is the main oil layer in the northern slope zone of Lish fault depression. Many researches have been done on the structural evolution, hydrocarbon source rock distribution and sequence stratigraphic division of Yingcheng formation in this area. But the study on the provenance and sedimentary system of the second member of the Yingshan formation is relatively low, which greatly restricts the exploration and development of oil and gas in this area. The distribution of provenance system and the distribution of sedimentary microfacies in the second member of the Ying formation are studied in detail by means of drilling log data analysis and 3D seismic data interpretation and processing. The second member of the formation is divided into SG1. SG2 and SG3 sand formation, among which SG1 sand group has higher sandstone content and coarse grain, and the sand body superposition mode is mainly precession; The sandstone of SG2 sand formation has fine granularity, mainly mudstone intercalated sandstone deposit, deep mudstone color, and sand body superposition mode is mainly retrogradation and accretion. The sandstone grains of SG3 sand formation become thicker, and the sand body appears to be progressive and superimposed. In a word, the formation thickness of each sand formation in the Ying2 member of the northern slope belt shows the characteristics of "east thin west thick, north thin south thick". It is assumed that the sedimentary center is located in the southwest of the study area. It is found that the characteristics of heavy minerals, conglomerate content and mudstone color distribution are analyzed synthetically. The provenance direction of the second member of the Ying formation is slightly different in different periods, and the provenance of the sand formation mainly comes from the northern and western parts of the basin. The SG2 sand formation is greatly affected by the northern provenance. In the study area, the following six sedimentary microfacies were identified: braided river delta front underwater distributary channel, estuarine dam, underwater distributary bay, shoreside shallow lake dam. Sand flat and shore shallow lake mud. The second member of the camp mainly developed in shallow water environment, except for the widely distributed shallow-lake muddy sediment, the SG1 sand formation developed microfacies of underwater distributary channel and estuarine dam. During the sedimentary period of the SG2 sand formation, the lacustrine basin was enlarged, mainly by the shore-shallow lacustrine subfacies, and by the common beach and dam microfacies. The SG3 sand formation is mainly composed of braided river delta front estuarine dams and interbay microfacies of underwater distributary. The distribution of the complex provenance system and the distribution of sedimentary facies are also studied. The sedimentary evolution characteristics of each sand formation in the second member of the study area. SG1 period, shallow lake depth, wide distribution of sand bodies in the north braided river delta front, and southward progradation. During the SG2 period, the lake basin water area expanded, the north braided river delta front sand body retreated to the north, and the spreading range decreased relatively. The southern part of the study area developed a large area of shallow-lake muddy sediments. During the sedimentary period of the SG3 sand formation, the lake level decreased, and the braided river delta front sand bodies showed zonal distribution in the north, while the longitudinal development of the braided river delta front sandbodies was characterized by inheritance and weak cyclicity.
【学位授予单位】：中国地质大学(北京)
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：P618.13
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本文编号：1485048