南堡凹陷东营组堆积期构造活动的“双强效应”及其对沉积的控制

发布时间：2018-08-08 19:42

【摘要】：南堡凹陷位于渤海湾盆地黄骅坳陷东北部,是渤海湾盆地中“小而肥”的富油气凹陷。在详细分析南堡凹陷东营组沉积期构造地层特征、边界断裂活动性、基底沉降特征、凹陷伸展特征,并与沙河街组沉积期进行纵向对比,与周邻地区东营组沉积期进行横向对比的基础上,总结了南堡凹陷东营组沉积期构造活动不同于渤海湾盆地其它坳陷(凹陷),甚至多数处于断拗转换期坳陷(凹陷)的特殊性：一方面边界断裂活动强烈,尤其以近EW向延伸的西南庄断裂中段和高柳断裂的强烈活动为特征。另一方面沉降中心并不沿边界断裂展布,而是位于凹陷中部的林雀次凹和曹妃甸次凹处,表明拗陷作用也强烈。构造-地层格架剖面上,Ed构造层在紧邻边界断裂下降盘处和远离边界断裂的中央凹陷带均发育厚层地层,显示边界断裂活动和拗陷作用对沉积均有明显控制。本次研究将南堡凹陷东营组沉积期边界断裂活动强烈、拗陷作用也强烈的特征称为构造活动的“双强效应”。构造活动的“双强效应”控制下,凹陷基底沉降强烈,Ed3s沉积时期基底沉降速率甚至超过古近纪早期(强烈断陷期)。东营组沉积期,渤海湾盆地普遍进入断拗转换期。不同于渤海湾盆地其它坳陷(凹陷)发育河流相、滨浅湖相或辫状河三角洲为主的沉积体系,构造活动的“双强效应”控制下,南堡凹陷呈现出不同的沉积面貌：①半深湖-深湖沉积环境广泛发育,且远离边界断裂向凹陷中部迁移,凹陷处于欠补偿-补偿状态；②强烈的基底沉降为碎屑物堆积提供了充足的可容纳空间,加之物源碎屑供给充足,较短的时间内堆积了巨厚的东营组地层；拗陷作用控制下,地层厚度中心展布在凹陷中部的林雀次凹和曹妃甸次凹处,同时边界断裂的强烈活动使得紧邻断裂下降盘处发育局部厚度高值带；⑧边界断裂下降盘处较陡的构造坡降,以及凹陷中部强烈的基底沉降,为扇三角洲沉积体系、近岸水下扇沉积体系和滑塌重力流沉积体系的发育提供了合适的坡降条件和可容纳空间。北部断控陡坡带扇三角洲沉积体系十分发育,数个朵体呈裙带状向凹陷中心进积,不仅展布范围非常广,而且扇体堆积厚度大,南部缓坡带则发育了辫状河三角洲沉积体系。构造活动的“双强效应”控制下,南堡凹陷东营组中深湖相沉积环境堆积了厚层暗色泥岩。Ed3泥岩分布广,厚度大,有机质丰度高,有机质类型好,在后期较高埋深及较高地温梯度下,已进入中等成熟演化阶段,成为南堡凹陷内优质烃源岩,提供了10%的资源量。Ed2发育一套分布广、单层厚度大且稳定的半深湖相泥岩,虽然成熟度较低,不能成为优质烃源岩,但在南堡凹陷断裂异常发育的背景下,可以有效封堵油气,构成了区域性盖层。南堡凹陷东营组沉积相类型丰富,以扇/辫状三角洲前缘河口坝砂体、扇/辫状三角洲平原水下分流河道砂体、滑塌浊积岩为主的中-高孔、中-高渗的砂岩层是较好-好储层,使得东营组优质储层非常发育,范围广且类型齐全。构造活动的“双强效应”控制下,优质烃源岩、类型丰富的优质储层以及区域盖层的发育,使得南堡凹陷东营组具有极大的勘探潜力。最后,对构造活动的“7双强效应”成因机制进行了探讨。东营组沉积期,渤海湾盆地普遍进入断拗转换期,由热沉降引起的拗陷作用以渤中坳陷为中心向周围大致呈递减的趋势,紧邻渤中坳陷的南堡凹陷拗陷作用强烈。此外,Esl沉积晚期南堡凹陷大规模岩浆喷发后,由于热量的迅速衰减,岩浆房附近浅表层地壳的均衡沉降,也可能是东营组(尤其是东营组早期)拗陷作用强烈的原因。Es1-Ed沉积时期,太平洋板块对欧亚大陆向西俯冲突然加速,导致渤海湾盆地东部边界-郯庐断裂右旋走滑,以及穿过黄骅坳陷的兰聊断裂北段活化并走滑,郯庐断裂和兰聊断裂的走滑活动在黄骅坳陷东北部派生出近SN向伸展叠加区,导致NNE向延伸的黄骅坳陷边界断裂-沧东断裂的正向伸展作用大幅度减弱,走滑分量急剧增强,沉降中心和断裂活动中心逐渐偏离边界断裂向坳陷内部迁移,Ed沉积时期迁移到南堡凹陷,导致以近EW走向为代表的边界断裂活动的显著增强。因此,构造活动的“双强效应”是深部动力过程与浅部构造应力场综合作用的产物。
[Abstract]:Nanpu Sag, located in the northeast of the Huanghua depression in the Bohai Bay Basin, is a "small and fat" oil and gas depression in the Bohai Bay basin. The structural stratigraphic characteristics of the Dongying formation in the Nanpu Sag, the activity of boundary faults, the characteristics of the basement subsidence and the sag extension are analyzed in detail, and the vertical comparison with the depositional period of the Shahe Street Group and the east of the neighbouring area are in the East. On the basis of horizontal comparison of the sedimentary period, the tectonic activity of Dongying formation in Nanpu Sag is different from that of other depression (SAG) in Bohai Bay Basin, and most of them are in the special characteristics of depression (SAG) in the transition period of fault depression. On the one hand, the boundary fault activity is strong, especially in the middle section of the southwestern Zhuang fault and the high willow fault in the near EW direction. On the other hand, the settlement center is not distributed along the boundary of the boundary, but in the Lindu subsag and Caofeidian subsurface in the middle of the depression, indicating that the depression is also strong. On the tectonic stratigraphic shelf section, the Ed tectonic layer is thicker than the central depression adjacent to the boundary fault drop plate and the far off boundary fault. In this study, the boundary fault activity and the depression of the Dongying formation in Nanpu Sag are strongly controlled by the boundary faults, and the strong depression of the depression is called the "double strong effect" of tectonic activity. Under the control of "double strong effect" of tectonic activity, the subsidence of the sag basement is strong and the Ed3s sedimentary period base is under the control of the tectonic activity. The bottom subsidence rate is even more than the early Paleogene (strong fault depression period). The Bohai Bay basin generally entered the fault depression period in the Dongying formation period. The sedimentary system is different from the other depression (depression) of the Bohai Bay Basin, the shallow lake facies or the braided river delta, and the Nanpu Sag under the control of the "double strong effect" of the construction activities. There are different sedimentary features: (1) the sedimentary environment of the semi deep lake deep lake is widely developed, and it is far away from the boundary fault to the middle of the depression, and the depression is in the state of compensation and compensation, and the strong basement settlement provides sufficient space for the accumulation of debris, and the debris supply is sufficient and the thick East is accumulated in a relatively short time. Under the control of the depression, the thickness center of the formation is distributed in the Lin Finch and Caofeidian subfovea in the middle of the depression, while the strong activity of the boundary fault causes the high local thickness zone to be developed at the descending plate near the adjacent fault, the steep tectonic slope at the descending plate of the boundary fault and the strong basement subsidence in the middle of the depression. The fan delta depositional system, the offshore subaqueous fan depositional system and the slump gravity flow depositional system provide the appropriate slope conditions and accommodating space. The fan delta depositional system in the northern faulted steep slope zone is very developed, several of which show a belt to the center of the sag, not only a very wide range of distribution, but also a large thickness of the fan body. Under the control of "double strong effect", the deep lacustrine sedimentary environment in the Dongying formation of Nanpu Sag, under the control of the "double strong effect" of tectonic activity, has accumulated a thick dark mudstone of the deep lacustrine sedimentary environment of the Dongying formation in Nanpu Sag, with a wide distribution, large thickness, high organic matter abundance and good organic matter type, which has entered into a higher buried depth and a higher temperature gradient in the later period. The medium maturity evolution stage has become a high quality source rock in Nanpu Sag, which provides 10% resources.Ed2 to develop a set of large and stable semi deep lacustrine mudstones with a large and stable single layer. Although the maturity is low, it can not be a high quality source rock, but under the background of abnormal development of Nanpu Sag, the oil and gas can be effectively blocked and the region is formed. The sedimentary facies of Dongying formation in Nanpu Sag is rich in sedimentary facies, with fan / braided delta front edge estuary sand body, fan / braided delta plain water distributary channel sand body, slumped turbidite mainly middle and high pore, medium high permeability sandstone layer is good good reservoir, which makes Dongying formation high quality reservoir very developed, wide range and complete type. Under the control of "double strong effect", the high quality hydrocarbon source rocks, rich types of high quality reservoirs and the development of regional caprock have made the Dongying formation of Nanpu Sag have great potential for exploration. Finally, the formation mechanism of the "7 double strong effects" of tectonic activity was discussed. In the sedimentary period of the Dongying formation, the Bohai Bay basin generally entered the transition period of fault depression. The depression caused by thermal subsidence is roughly decreasing in Bozhong depression, close to the Nanpu depression in Bozhong depression. In addition, the rapid attenuation of heat and the equilibrium settlement of the shallow crust near the magma chamber in the late Nanpu depression of the late Esl deposit may also be the Dongying formation. It is the cause of strong depression in the early Dongying formation. The period of.Es1-Ed deposition was caused by the sudden acceleration of the Pacific plate to the West subduction, the eastern boundary of the Bohai Bay Basin, the Tan Lu fault, the dextral strike slip, and the north section of the Lanliao fault, which passed through the Huanghua depression, and the strike slip of the north section of the Lanliao fault, and the strike slip of the Tanlu fault and the Lanliao fault in Huang Huaao. In the northeast, the near SN extension superposition area is derived, which leads to the positive extension of the Huanghua depression boundary fault - the Cangdong fault, which leads to the NNE extension. The strike slip component increases sharply, the settlement center and the fault center gradually deviate from the boundary faults and migrate to the depression, and the Ed deposition period migrates to Nanpu Sag, leading to the near EW walk. Therefore, the "double strong effect" of the tectonic activity is the product of the comprehensive action of the deep dynamic process and the shallow tectonic stress field.
【学位授予单位】：中国地质大学
【学位级别】：博士
【学位授予年份】：2016
【分类号】：P618.13

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