地学前缘 ›› 2021, Vol. 28 ›› Issue (1): 33-42.DOI: 10.13745/j.esf.sf.2020.5.3

• 构造沉积响应 • 上一篇    下一篇

济阳坳陷桩海地区古生界潜山构造特征及形成机制

罗霞1(), 方旭庆2, 张云银1, 张云涛1   

  1. 1. 中国石化胜利油田分公司 物探研究院, 山东 东营 257015
    2. 中国石化胜利油田分公司 油气勘探管理中心, 山东 东营 257015
  • 收稿日期:2020-03-10 修回日期:2020-05-19 出版日期:2021-01-25 发布日期:2021-01-28
  • 作者简介:罗霞(1973—),女,博士,研究员,油气勘探专业,主要从事盆地构造解析与油气地质综合研究。E-mail: 292947193@qq.com
  • 基金资助:
    国家油气重大专项课题“渤海湾盆地精细勘探关键技术”(2016ZX05006);中石化科技攻关项目“济阳坳陷中—古生界构造演化与潜山形成分布”(P19015-1)

Structural characteristics and formation mechanism of the Palaeozoic buried hills of the Zhuanghai area in the Jiyang Depression

LUO Xia1(), FANG Xuqing2, ZHANG Yunyin1, ZHANG Yuntao1   

  1. 1. Geophysical Exploration Research Institute, SINOPEC Shengli Oilfield Company, Dongying 257015, China
    2. Petroleum Exploration Management Center, SINOPEC Shengli Oilfield Company, Dongying 257015, China
  • Received:2020-03-10 Revised:2020-05-19 Online:2021-01-25 Published:2021-01-28

摘要:

济阳坳陷古生界潜山在经历了残丘山勘探阶段、多样性潜山勘探阶段之后,位于正向构造单元之间的中低位序复杂隐蔽潜山成为勘探主要方向。桩海地区东部紧邻郯庐断裂带,郯庐断裂带的多期构造运动对其产生深刻影响,古生界潜山构造样式非常复杂,并且由于埋藏深,前期地震资料精度低,构造特征认识不清,制约了勘探进展。该研究针对济阳坳陷桩海地区古生界复杂构造特征,运用高精度三维地震、钻井资料和区域应力场研究结果,探讨桩海地区古生界复杂构造特征及其形成机制。桩海地区古生界发育一套稳定的海相-海陆过渡相沉积岩系,自下而上依次发育寒武系、奥陶系、石炭系和二叠系。桩海地区古生界发育北西、南北、北东和东西4组走向的断裂,断层类型有正断层、逆断层和走滑断层。北西走向断裂5条,倾角较陡,平面上呈现正、逆相间分布的特点。南北走向断裂3条,剖面呈“花状”特征,为走滑断层。北东走向断裂为正断层,该组断层切割北西向断裂组。东西走向断裂主要是桩海地区潜山的南、北边界断层,该组断层切割北西走向断裂组。断层活动时期可划分为4期。第一期为印支期挤压形成的逆断层,断层贯穿古生界;第二期为晚侏罗至早白垩世构造反转形成的正断层,贯穿中生界和古生界;第三期为晚白垩世挤压形成的逆冲断层,贯穿中生界和古生界;第四期为始新世以来走滑和伸展形成的正断层,断层贯穿古生界、中生界、古近系和部分新近系。不同走向断层交汇切割,形成“棋盘格”式复杂构造。古生界顶面整体呈中部高、东西两侧低的背斜形态。自西向东可划分4排山。复杂的演化过程决定了不同潜山带保留层系和结构类型的差异性。对形成机制的研究结果表明:三叠纪末期—始新世,在郯庐断裂左旋→右旋“往返式”走滑变应力场控制下,桩海地区古生界经历了“挤压-拉张-挤压-走滑”4个演化阶段。三叠纪末期,在郯庐断裂左旋走滑运动下,桩海地区受到NE-SW向挤压、形成3条北西走向逆冲带;晚侏罗—早白垩世,桩海地区经历NW-SE向拉张,逆冲断层发生不均衡反转,形成北西向断层正、逆相间的特征,分割形成北西走向4排山雏形;晚白垩世,在郯庐左旋→右旋转换作用下,桩海地区受到NWW-SEE向挤压,经历二次挤压推覆,第二—四排山自东向西推覆,对古生界进行一次改造,基本奠定古生界构造格局;始新世,在郯庐断裂右旋走滑运动下,产生近南北向和北东向走滑断层及东西走向调节断层,切割早期北西向断裂组,同时在南、北边界断层伸展作用下,桩海地区发生南升北降翘倾运动,古生界构造样式定型,形成现今复杂的构造样式。构造演化控制桩海地区古生界潜山结构和成藏条件有所差异。自东向西地层逐渐减薄,西部地层剥蚀严重,第一排山仅保留寒武系,向东部的三排山保留的奥陶系逐渐增厚。第一排山发育寒武系断块圈闭,第二排山发育奥陶系—寒武系背斜圈闭,第三、四排山发育奥陶系—寒武系断块圈闭。从两侧向中间由断块山变为褶皱山、储集性变好,以第二排山奥陶系—寒武系逆冲褶皱山成藏最有利。

关键词: 构造特征, 应力场, 翘倾运动, 郯庐断裂, 桩海地区, 济阳坳陷

Abstract:

In the Paleozoic buried hills of the Jiyang Depression, the complex middle-lower section between the positive structural units has become the main exploration focus after the initial prospecting of the residual hill and peripheral buried hills. The eastern part of the Zhuanghai region is close to the Tanlu fault zone and has been profoundly impacted by its multistage tectonic movements. The structural style of the Zhuanghai Paleozoic buried hill is very complex, and deep burial can result in low accuracy in the early seismic data, causing ambiguous structural characterization of the zhuanghai area thus greatly hindering the exploration progress. In this paper, we discussed the complex structural characteristics and formation mechanism of the Paleozoic buried hills of the Zhuanghai area, using high precision 3D seismic and drilling data and regional stress field test results. Our results showed that a set of paleozoic stable marine and transitional sedimentary rock series developed in the Zhuanghai area, where Cambrian, Ordovician, Carboniferous and Permian series developed successively from bottom to top. There are four groups of different types of Paleozoic faults in the Zhuanghai area, grouped as the NW, SN, NE and EW-trending faults. The five NW-trending faults are high angle normal and reverse faults; the three NS-trending faults are strike-slip faults; the NE-trending faults, which cut through the NW-trending fault group, are normal faults; and the EW faults, crossing the NW fault group, are mainly the southern and northern boundary faults of the Zhuanghai buried hills.

The fault development can be divided into four periods: the first period in the Indosinian when reverse faults formed by Paleozoic compression; the second period from the Late Jurassic to Early Cretaceous when normal faults formed by structural reversions through the Mesozoic-Paleozoic era; the third period in the Late Cretaceous when thrust faults formed by Mesozoic-Paleozoic compression; and the fourth period in the Eocene when normal faults formed by strike slip and extension movements through the Paleozoic-Mesozoic-Paleogene-Neogene period. Intersecting and intercutting faults of different trendings formed a “chessboard” type complex structure. The Paleozoic top surface resembled a W-E trending anticline and can be divided from west to east into four rows of buried hills. The complex evolutionary process is responsible for the disparity in the reserved strata and for the structural types of different rows of buried hills. Formation mechanism study showed that the Late Triassic to Eocene Paleozoic Zhuanghai strata underwent four stages of evolution: compression, extension, compression, and strike-slip, under the control of the reciprocating strike-slip stress field of the Tanlu fault. At the end of the Triassic, three NW-trending thrust fold belts formed under the control of the NE-SW-trending compression by the sinistral strike-slip movement of the Tanlu fault in the Zhuanghai area. From the Late Jurassic to Early Cretaceous, the thrust faults reversed unevenly, resulting in the NW-trending alternation of normal and thrust faults. In this period, four rows of NW-trending buried hills were formed. The Zhuanghai area of the Late Cretaceous experienced a 2nd NWW-SEE-trending compression, under a conversional stress field of the Tanlu fault in a sinistral to dextral strike slip movement. From the second to the fourth row of the buried hills, the strata were napped from east to west and the Paleozoic structures were reconstructed again to establish the basic structural pattern of the Paleozoic. In the Eocene, the NS-trending faults, NE-trending strike slip faults and EW-trending adjustment faults were formed by the dextral strike slip movement of the Tanlu fault, intersecting the early formed NW-trending faults and a south to north downward tilting movement occurred in the Zhuanghai area at the same time to form the present-day complex structural styles. The structural evolution controlled the disparities in the buried hill structures as well as reservoir forming conditions in the Paleozoic Zhuanghai area. The stratum gradually thinned from the east to the seriously eroded west. The first row of buried hills only retained Cambrian strata, while Ordovician strata reserved in the three rows to the east gradually thickened. The first row of buried hill developed fault block traps of Cambrian strata; the second row developed anticline traps of Ordovician and Cambrian strata; and the third and fourth rows developed fault block traps of Ordovician and Cambrian strata. The trap types changed from fault block on both sides to fold in the middle, resulting in better reservoirs. The second row of Ordovician thrusting fold hills are most favorable for forming reservoirs.

Key words: structure characteristics, stress field, tilting movement, Tanlu fault, Zhuanghai area, Jiyang Depression

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