峡谷水道壁沉积构成、沉积特征及勘探意义  

Sedimentary composition,sedimentary characteristics,and exploration significance of canyon channel walls

作　　者：陈韶娟 李东伟 CHEN Shaojuan;LI Dongwei(School of Geosciences,Yangtze University,Wuhan,Hubei 430100,China;State Key Laboratory of Petroleum Resources and Engineering,China University of Petroleum,Beijing,Beijing 102249,China;College of Geosciences,China University of Petroleum,Beijing,Beijing 102249,China)

机构地区：[1]长江大学地球科学学院,武汉430100 [2]油气资源与工程全国重点实验室(中国石油大学(北京)),北京102249 [3]中国石油大学(北京)地球科学学院,北京102249

出　　处：《中国海上油气》2025年第2期132-141,共10页China Offshore Oil and Gas

基　　金：国家自然科学基金企业创新发展联合基金重点支持项目“南海北部深水区深层温压场差异性演化对优质储层的控制机理(编号:U24B2016)”;中海石油(中国)有限公司科技项目“琼东南浅水区古近系构造演化控制下的差异成藏研究(编号:CCL2022HNFN0434)”部分研究成果。

摘　　要：地质学家对深水峡谷水道的研究长期聚焦在内部充填,忽略了侧壁的刻画,导致“峡谷水道壁的沉积特征及勘探意义”的研究基本处于空白。本文利用琼东南盆地晚中新世地震资料和智利上白垩统Tres Pasos组露头资料,综合钻井揭示、地震正演和露头解剖,系统剖析了峡谷水道壁的沉积构成及特征。钻井显示峡谷水道壁由一套10~40 m厚、高密度、高波阻抗、呈齿化箱状伽马曲线特征的泥岩组成;地震正演证实其呈下切状、厚约半个波长的地震反射同相轴,是与围岩斜交的高密度、高波阻抗泥岩。露头解剖表明峡谷水道壁厚约几十厘米到十余米,轴部被侵蚀,具边缘厚、轴部薄的特点;其底层沉积泥质较多(>80%~90%),顶层沉积泥质减少(>65%),均可见由小型交错层理细砂—极细砂(Tc)递变为水平和块状层理粉砂岩—泥岩(Td—e)的相序。研究提出峡谷水道壁可作为油气横向运移遮挡层,在浊积砂体的上倾方向被后期峡谷水道侵蚀时可形成水道壁遮挡型岩性圈闭,这类岩性圈闭在琼东南盆地深水区已经得到实钻验证。本文研究对深水环境岩性圈闭的勘探具有参考价值。Geologists’research on deep-water canyon channels has long focused on internal filling,but ignored the characterization of the side walls,which results in a research gap in“sedimentary characteristics and exploration significance of canyon channel walls”.Based on employing seismic data from the Miocene in Qiongdongnan Basin and outcrop data from the Upper Cretaceous Tres Pasos Formation in Chile,this paper combined well drilling revelations,seismic forward modeling,and outcrop dissection to finely analyze the sedimentary composition and characteristics of canyon channel walls.Well drilling data reveals that the canyon channel walls consist of a set of mudstones with 10-40 m thickness,high density,high wave impedance,and toothed box-shaped Gamma curve characteristics.Seismic forward modeling confirms that canyon channel walls are high-density and high wave impedance mudstones with a downward cutting shape and thickness of about half the wavelength in a single seismic reflection event,intersecting the surrounding rocks.Outcrop dissection reveals that in addition to the eroded central part,canyon channel walls vary in thickness from tens of centimeters to more than ten meters,showing the characteristic of“thick edges and thin centers”.The bottom layer has relatively high mud content(>80%-90%),while the top layer has slightly reduced mud content of more than 65%.Both of them show the phase sequence change from fine sand-very fine sand(Tc)with small cross-bedding to siltstone-mudstone(Td-e)with horizontal and massive bedding.This study suggests that canyon channel walls can serve as barrier layers for lateral migration of oil and gas.When the canyon channels erode the turbidite lobes in the upward direction,lithologic traps which are laterally trapped by canyon channel walls can be formed.This kind of lithologic trap has been verified by exploration wells in the Qiongdongnan Basin.Therefore,this study provides references for lithologic trap exploration in deep-water environments.

关 键 词：峡谷水道壁 沉积构成 沉积特征 岩性圈闭 

分 类 号：TE121.3[石油与天然气工程—油气勘探]