地学前缘 ›› 2021, Vol. 28 ›› Issue (1): 282-294.DOI: 10.13745/j.esf.sf.2020.5.26

• 致密/页岩储层 • 上一篇    下一篇

海相断陷盆地输导体系分类及组合模式特征: 以琼东南盆地古近系陵水组为例

陈欢庆1(), 朱筱敏2, 张功成3, 张亚雄4, 张琴2, 刘长利5   

  1. 1. 中国石油勘探开发研究院, 北京 100083
    2. 中国石油大学(北京) 地球科学学院, 北京 102249
    3. 中海油研究总院, 北京 100028
    4. 中国石化石油勘探开发研究院, 北京 100083
    5. 吉林大学 地球科学学院, 吉林 长春 130061
  • 收稿日期:2019-12-05 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:陈欢庆(1979—),男,博士,高级工程师,矿物学、岩石学、矿床学专业,主要从事油气田地质研究。E-mail: hqchen2009@163.com
  • 基金资助:
    国家重点基础研究发展计划“973”项目(2009CB219400)

Classification and combination model characteristics of pathway system in marine faulted basin: Taking the Paleogene Lingshui Formation, Qiongdongnan Basin as an example

CHEN Huanqing1(), ZHU Xiaomin2, ZHANG Gongcheng3, ZHANG Yaxiong4, ZHANG Qin2, LIU Changli5   

  1. 1. Research Institute of Petroleum Exploration & Development, PetroChina, Beijing 100083, China
    2. College of Geosciences, China University of Petroleum(Beijing), Beijing 102249, China
    3. CNOOC Research Institute, Beijing 100028, China
    4. SINOPEC Petroleum Exploration and Production Research Institute, Beijing 100083, China
    5. College of Earth Sciences, Jilin University, Changchun 130061, China
  • Received:2019-12-05 Revised:2020-05-19 Online:2021-01-25 Published:2021-01-28

摘要:

以琼东南盆地古近系陵水组为例,针对海相断陷盆地钻井资料少、地震资料复杂、断裂体系发育、地层破碎、有利勘探目标预测难度大等问题。在Vail经典的层序地层学理论指导下,基于浅水区钻井资料和深水区地震资料,井震资料紧密结合建立研究区目的层三维等时地层格架,将目的层划分为层序Ⅰ、层序Ⅱ、层序Ⅲ和层序Ⅳ4个三级层序。岩石类型、沉积构造、自生矿物和生物化石4方面证据表明,研究区目的层为海相沉积。在等时地层格架内,通过沉积学分析、断裂体系解释和不整合面刻画等工作,对每一种地质成因输导体开展单要素分析。从成因角度将研究区目的层输导体系划分为储集体、断裂和不整合面3种主要类型,并对不同类型输导体系在空间上的发育特征进行精细刻画。低位体系域的斜坡扇、盆底扇,海侵体系域的扇三角洲、滩坝和滨岸砂,高位体系域的扇三角洲和辫状河三角洲等是储集体输导体系的主要对应沉积相类型。北东向展布的控凹大断裂可以成为油气运移输导的有利通道。根据成因和输导效果将不整合划分为平行不整合、超覆不整合、削蚀不整合和超覆-削蚀不整合共4大类。层序界面上广泛发育的不整合面可以成为油气运移输导的有利通道,在油气运移输导过程中承担重要的角色。分析不同输导体系在空间上的组合特征,将研究区目的层输导体系模式总结为断层+不整合面(储集体)“T”型输导、断层+不整合面(储集体)梳状型输导、断层+储集体网格型输导、断层+不整合面阶梯型输导、裂隙型输导(裂缝+层理面+孔隙)5种类型,指出不同输导体系模式在盆地内分布的位置和分布规律,并建立了油气疏导体系模型。结合盆地温度场、压力场、流体势等石油地质特征及烃源岩、盖层等成藏要素分析,预测有利的油气勘探区带。区域上有利的勘探区带主要包括崖南凹陷北缘、松西凹陷、松南凹陷北缘、北礁凹陷周缘、陵水南斜坡、长昌凹陷北缘和南缘。4个层序中,层序Ⅰ最有利,层序Ⅲ和层序Ⅳ次之,层序Ⅱ最差。

关键词: 琼东南盆地, 陵水组, 输导体系, 地震相, 储集体, 断裂, 不整合面, 输导体系模式

Abstract:

Taking the Lingshui Formation of the Paleogene in the Qiongdongnan Basin as an example, the problems associated with oil and gas exploration include limited drilling data, complex seismic data, development of fault system, and difficulty predicting favorable exploration targets. In this study, under the guidance of the classical sequence stratigraphy theory of Vail, we established the isochronal stratigraphic framework by closely combining the shallow water drilling data with the deep water seismic data in delineating the target strata into four three-level sequences. Evidences from rock types, sedimentary structures, authigenic minerals and biological fossils showed that the target strata formed in a marine sedimentary environment. In the isochronous stratigraphic framework, we carried out the single element analysis for each geogenetic pathway system through sediment analysis, fault system interpretation, and unconformity characterization. The pathway system of the target strata was genetically divided into three main types-reservoir, fracture and unconformity, and we described in detail the spatial developmental characteristics of different types of transport systems. The slope and pelvic floor fans in the lower system domain, the fan delta, beach bar and shore sand in the pathway system domain, and the fan delta and braided river delta in the higher system domain are the main sedimentary facies types corresponding to the reservoir transport system. The large controlling concave fault spreading in the northeast can be a favorable channel for oil and gas migration. The unconformity is divided into four categories: parallel, overlap, truncation and overlap-truncation unconformities. The widely developed unconformity in the sequence interface can be a favorable migration channel and plays an important role in oil/gas migration and transmission. We further analyzed the spatial combinations of different pathway systems and summed up the modes of combination into six types: fault+unconformity (reservoir) or “T” type transport, fault+unconformity (reservoir) or comb type transport, fault+reservoir or grid type transport, fault+unconformity or stepped type transport, and fracture type transport (fracture+bedding surface+pore). We then located each type of pathway system in the basin, and established the pathway system model. Based on the analysis of petroleum geological characteristics, such as temperature/pressure field and fluid potential as well as hydrocarbon source rock and cap rock, we predicted the favorable oil and gas exploration zones, which mainly included the north margin of the Yanan Depression, the Songxi Depression, the north margin of the Songnan Depression, the periphery of the North Reef Depression, the south slope of the Lingshui Depression, and the north and south margins of the Changchang Depression. Among the four sequences, sequence Ⅰ was the most favorable zone, followed by sequences Ⅲ and IV, whereas sequence Ⅱ was the least favorable zone.

Key words: Qiongdongnan Basin, Lingshui Formation, pathway system, seismic facies, reservoir, fault, unconformity, combination model of pathway system

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