塔里木盆地寒武系膏盐岩沉积特征与发育模式

Sedimentary characteristics and development model of Cambrian gypsum-salt rocks, Tarim Basin

樊奇 樊太亮 李清平 杜洋 张岩 苑雅轩

FAN Qi FAN Tailiang LI Qingping DU Yang ZHANG Yan YUAN Yaxuan

中海油研究总院有限责任公司, 北京 100028 中国地质大学(北京) 能源学院, 北京 100083 中国海洋石油国际有限公司, 北京 100028

CNOOC Research Institute Limited, Beijing 100028, China School of Energy, China University of Geosciences(Beijing), Beijing 100083, China CNOOC International Limited, Beijing 100028, China

塔里木盆地寒武系膏盐岩是塔里木盐下—盐间勘探领域的基本地质要素，也是典型海相蒸发岩沉积序列，但目前对这套蒸发岩的关注较少。通过野外勘测、最新二维地震解释、中央隆起16口探井资料综合分析，以“点—线—面”思路开展了膏盐岩沉积特征研究，编制了中—下寒武统盖层、膏盐岩层等厚图和阿瓦塔格组沉积相图，建立了中—下寒武统膏盐岩“干热古气候+持续海退过程+礁体障壁背景”发育成因模式。中—下寒武统吾松格尔组和阿瓦塔格组纵向稳定发育4种岩相组合的4套膏盐岩盖层，海退期膏盐岩具有“内盐—中膏—外红层”的“牛眼”特征；海侵期膏盐岩具有与膏云岩、膏泥岩的互层沉积特征。塔里木盆地中—下寒武统盖层均厚245 m，膏盐岩均厚167 m（最厚达340 m），具有优越的区域封盖能力。分析认为，干旱炎热的古气候、持续海退过程、礁体障壁条件为塔里木早—中寒武世厚层膏盐岩发育提供了有利条件，古气候和海平面变化制约了局限台地和蒸发台地的相带边界，使巴楚隆起、阿瓦提坳陷（膏盐岩稳定厚度300 m以上）成为了当时的聚盐中心。

The Cambrian gypsum-salt rocks in the Tarim Basin are key geological elements to the pre-salt play typical marine evaporites, yet little attention has been paid to this set of evaporites. Based on a field survey, the latest 2D seismic interpretation and comprehensive analysis of sixteen exploratory wells, a study on the sedimentary characteristics of gypsum-salt rock was carried out in a progression of "point to line, and to plane", and a contour map of the Lower to Middle Cambrian cap rocks, gypsum-salt rocks and the sedimentary facies maps of the Awatag Formation were compiled. A development model of "dry and hot paleoclimate, continuous regression process, reef barrier background" of the Lower to Middle Cambrian gypsum-salt rocks was established. There are four sets of gypsum-salt rocks with four lithofacies combinations developed longitudinally and stably in the Wusongger and Awatag formations. The gypsum-salt rocks in the regression stage are featured by "inner salt, middle gypsum, outer red-layer", while those in the transgression stage are interbedded with gypsum, mudstone and dolomite. The average thickness of the Lower to Middle Cambrian cap rocks in the Tarim Basin is 245 m, and the average thickness of the gypsum-salt rocks is 167 m (340 m maximum), showing good sealing capacity. The arid-hot paleoclimate, continuous regression and reef and reef barrier provided favorable conditions for the development of thick gypsum-salt rocks in the Early to Middle Cambrian of the Tarim Basin. The paleoclimate and sea level change restricted the facies boundary between limited platform and evaporation platform, and made the Bachu Uplift and Awati Sag (the stable thickness of gypsum-salt rocks is over 300 m) become the salt accumulation center at that time.

国家油气专项 2017ZX05005002;中科院战略先导科技专项 XDA1401020102;;国家自然科学基金 U19B2005;国家重点研发计划 2016YFC030400;国家重点研发计划 2019YFC0312301

https://doi.org/10.11781/sysydz202102217