珠江口盆地东部恩平12洼古近系文昌组古地貌演化及其对沉积充填的控制

doi:10.19657/j.geoscience.1000-8527.2020.036

摘要/Abstract

摘要：

珠江口盆地东部恩平12洼古近系文昌组湖盆沉积发育,但在构造活动及岩浆的相互作用下,湖盆沉积遭受强烈改造,严重制约着该区中深湖相烃源岩识别及油气勘探。在利用趋势外推法对恩平12洼文昌组进行古地貌恢复的基础上,分析了古地貌演化与沉积充填的匹配关系。结果表明:(1)中始新世恩平12洼文昌组为典型的箕状半地堑,受珠琼运动二幕构造作用影响,地层遭受强烈抬升剥蚀,其剥蚀地层主要为湖盆缓坡带辫状河三角洲沉积及滨浅湖相沉积;(2)恩平12洼残留地层主要为湖盆中心中深湖相和陡坡带扇体。基于以上认识推动该区A井的钻探并发现油层,证实了恩平12洼具有中深湖相烃源发育潜力,也证实并深化了古地貌恢复在改造型洼陷沉积充填研究的可靠性和重要性,为珠江口盆地东部强改造型洼陷的烃源潜力研究提供了思路。

关键词: 珠江口盆地, 文昌组, 沉积充填, 恩平12洼

Abstract:

Lacustrine sedimentation of the Enping 12 sub-sag was developed in the Paleocene Wenchang Formation.The lacustrine-facies sediments were substantially modified by a combination of tectonism and magmatism, which severely hampers source rock identification and hydrocarbon exploration. Based on paleogeomorphologic reconstruction with trend extrapolation, the relation between paleogeomorphologic evolution and sedimentary depression of the Enping 12 sub-sag is revealed. The results indicate that: (1) The Enping 12 sub-sag is a typical half-graben in the Wenchang Formation that was intensely denudated. The main denudation occurred in the braided river delta deposits and shore-shallow lacustrine deposits in the lacustrine basin gentle slope zone. (2) The fan bodies are located in the steep slope zone.Based on this study, well A was drilled and oil-bearing sequence was discovered, which confirms that Enping 12 sub-sag is a potential deep lacustrine hydrocarbon source. It also demonstrates the reliability and importance of paleogeomorphic reconstruction in studying sedimentary infill of modified depressions, and provides insight on estimating hydrocarbon resource potential for strongly modified depressions in the eastern Pearl River Estuary basin.

Key words: Pearl River Estuary Basin, Wenchang Formation, reconstruction, Enping 12 sub-sag

中图分类号:

罗泽, 闫正和, 谢明英, 梁杰, 吴静. 珠江口盆地东部恩平12洼古近系文昌组古地貌演化及其对沉积充填的控制[J]. 现代地质, 2020, 34(04): 710-717.

LUO Ze, YAN Zhenghe, XIE Mingying, LIANG Jie, WU Jing. Paleogeomorphologic Reconstruction, Evolution, and Sedimentary System Control on Wenchang Formation in Enping 12 Sub-sag, Eastern Pearl River Estuary Basin[J]. Geoscience, 2020, 34(04): 710-717.

图/表 7

图1 恩平凹陷洼陷划分及恩平12洼构造位置 [1]

Fig.1 Location of Enping 12 sub-sag and tectonic division of Enping sag[1]

图2 恩平12洼剥蚀类型及剥蚀量恢复方法(下文昌组)

Fig.2 Types of stratigraphic erosion and reconstruction methods in Enping 12 sub-sag(Lower Wenchang Formation)

图3 恩平12洼文昌期古地貌图

Fig.3 Palaeogeomorphology of Wenchang Formation in Enping 12 sub-sag

图4 1号(a)、2号(b)及3号(c)沟谷垂直物源方向及3号沟谷顺物源方向地震相特征(剖面位置见图3)

Fig.4 Seismic facies for vertical source direction of No.1(a), No.2(b) and No.3(c) valleys and along source direction of No.3 valley (location of profiles seeing Fig.3)

图5 恩平12洼地震反射结构与沉积响应关系(剖面位置见图1) (a)ab剖面;(b)cd剖面

Fig.5 Relationship between seismic reflection structure and sedimentary response of Wenchang Formation in Enping 12 sub-sag(locations of profiles seeing Fig.1)

图6 恩平12洼下文昌组(a)与上文昌组(b)沉积相

Fig.6 Sedimentary distribution of the lower and upper Wenchang Formation in Enping 12 sub-sag

图7 A井恩平组井壁岩心抽提烃地球化学特征

Fig.7 Geochemical characteristics of hydrocarbon extracted from sidewall cores of Enping Formation in well A

参考文献 17

[1]	于开平, 张功成, 梁建设, 等. 珠江口盆地恩平凹陷油气成藏条件研究[J]. 石油实验地质, 2011,33(5):509-512.
[2]	许新明, 姜建, 陈胜红, 等. 珠江口盆地恩平凹陷断层封堵性评价[J]. 现代地质, 2016,30(1):122-130.
[3]	许新明, 陈胜红, 王福国, 等. 珠江口盆地恩平凹陷断层特征及其对新近系油气成藏的影响[J]. 现代地质, 2014,28(3):543-550.
[4]	龚丽, 朱红涛, 舒誉, 等. 珠江口盆地恩平凹陷文昌组层序格架中中-深湖相烃源岩空间展布及发育模式[J]. 地球科学——中国地质大学学报, 2014,39(5):546-557.
[5]	刘强虎, 朱红涛, 杨香华, 等. 珠江口盆地恩平凹陷古近系文昌组地震层序地层单元定量识别[J]. 中南大学学报(自然科学版), 2013,44(3):1076-1082.
[6]	曾智伟, 杨香华, 舒誉, 等. 恩平凹陷古近系少井文昌组构造古地貌特征及砂体展布规律:少井条件下储集砂体预测与评价[J]. 现代地质, 2015,29(4):804-821.
[7]	王家豪, 刘丽华, 陈胜红, 等. 珠江口盆地恩平凹陷珠琼运动二幕的构造-沉积响应及区域构造意义[J]. 石油学报, 2011,32(4):588-595.
[8]	傅宁, 丁放, 何仕斌, 等. 珠江口盆地恩平凹陷烃源岩评价及油气成藏特征分析[J]. 中国海上油气, 2007,19(5):295-299.
[9]	刘丽华, 陈胜红, 于水明, 等. 恩平凹陷成藏条件分析及商业性突破[J]. 中国海上油气, 2011,23(2):76-80.
[10]	曾智伟, 杨香华, 舒誉, 等. 恩平凹陷北部陡坡带文昌组砂砾岩体发育特征及构造沉积响应[J]. 地质科技情报, 2014,33(6):60-69.
[11]	郝石生, 贺志勇, 高耀斌, 等. 恢复地层剥蚀厚度的最优化方法[J]. 沉积学报, 1988,6(4):93-98.
[12]	尹天放. 多种信息综合计算剥蚀厚度方法[J]. 石油勘探与开发, 1992,19(5):42-47.
[13]	何生, 王青玲. 关于用镜质体反射率恢复地层剥蚀厚度的问题讨论[J]. 地质论评, 1989,35(2):119-125.
[14]	张一伟, 李京昌, 金之钧, 等. 原型盆地剥蚀量计算的新方法——波动分析法[J]. 石油与天然气地质, 2000,21(2):88-91.
[15]	陈增智, 柳广第, 郝石生. 修正的镜质体反射率剥蚀厚度恢复方法[J]. 沉积学报, 1999,17(1):141-144.
[16]	加东辉, 徐长贵, 杨波, 等. 辽东湾辽东带中南部古近纪古地貌恢复和演化及其对沉积体系的控制[J]. 古地理学报, 2007,9(2):155-167.
[17]	宋凯, 吕剑文, 凌升阶, 等. 鄂尔多斯盆地定边—吴旗地区前侏罗纪古地貌与油藏[J]. 古地理学报, 2003,5(4):497-507.