准噶尔盆地哈山地区二叠系风城组细粒沉积特征与演化模式

Fine-grained sedimentary characteristics and evolution model of Permian Fengcheng Formation in Hashan area, Junggar Basin

李振明 熊伟 王斌 宋振响 宋梅远 孙中良 于洪洲 周健 吴小奇

LI Zhenming XIONG Wei WANG Bin SONG Zhenxiang SONG Meiyuan SUN Zhongliang YU Hongzhou ZHOU Jian WU Xiaoqi

中国石化 石油勘探开发研究院 无锡石油地质研究所，江苏 无锡 214126 页岩油气富集机理与有效开发国家重点实验室, 江苏 无锡 214126 中国石化 油气成藏重点实验室，江苏 无锡 214126 中国石化 胜利油田分公司 勘探开发研究院，山东 东营 257015

Wuxi Research Institute of Petroleum Geology, SINOPEC, Wuxi, Jiangsu 214126, China State Key Laboratory of Shale Oil and Gas Enrichment Mechanisms and Effective Development, Wuxi, Jiangsu 214126, China SINOPEC Key Laboratory of Petroleum Accumulation Mechanisms, Wuxi, Jiangsu 214126, China Exploration & Development Research Institute, Shengli Oilfield Company, SINOPEC, Dongying, Shandong 257015, China

准噶尔盆地西北缘哈山地区地质条件复杂，勘探难度大，明确该地区二叠系风城组烃源岩沉积与演化特征对拓展盆缘油气勘探具有重要意义。基于全岩XRD、元素地球化学、有机质丰度、薄片鉴定和岩相组合特征，开展了玛湖凹陷和哈山地区风城组沉积特征与岩性、岩相组合差异分析，恢复了该区古沉积环境演化序列，建立了古沉积演化模式。哈山地区风城组岩相组合特征及古沉积环境演化序列与玛湖凹陷高度相似，整体为火山背景下的碱湖多源混合细粒沉积建造，发育多种岩相组合，沉积古环境具有阶段性演化特征。哈山地区风二段典型碱性矿物的大量出现，揭示该地区发育除玛湖凹陷外的另一湖盆中心。风一段沉积时湖平面相对较高，水体盐度较低，气候半干旱，火山沉积发育，岩相以含有机质块状凝灰岩为主；风二下段沉积时湖盆开始萎缩，气候相对更干旱，水体开始变咸，环境更局限，岩相以富有机质层状云质泥岩为主；风二段顶部和风三段下部沉积时环境相对最封闭，水体盐度大，发育大量碱性矿物，岩相以富有机质纹层状含碱云质泥岩和富有机质纹层状混合质页岩为主；风三段上部沉积时陆源碎屑输入增多，咸化减弱，发育扇三角洲沉积体系，岩相以含有机质块状粉细砂岩为主。风城组沉积环境控制了有机质的富集程度，总体上，碎屑输入少、温暖湿润、盐度相对较小的深水环境更有利于有机质富集。

The geological conditions of Hashan area on the northwestern margin of the Junggar Basin are complicated and it is difficult to explore. It is of great significance to clarify the sedimentary and evolutionary characte-ristics of source rocks in the Permian Fengcheng Formation in this area for expanding oil and gas exploration on the basin margin. Based on the analysis of whole-rock XRD, elemental geochemistry, organic matter abundance, thin section identification, and lithofacies association characteristics, this paper conducted a comparative analysis of the sedimentary characteristics, lithology, and lithofacies association characteristics of the Fengcheng Formation in the Mahu Sag and Hashan area, restored the ancient sedimentary environment evolution sequence in the study area, and established a model of ancient sedimentary evolution. The research results show that the lithofacies association characteristics and ancient sedimentary environment evolution sequence of the Fengcheng Formation in the Hashan area are highly similar to those in the Mahu Sag, which are generally fine-grained sediments mixed from multiple sources in an alkaline lake with a volcanic background, and various lithofacies associations are developed. The sedimentary paleoenvironment has phased evolution characteristics. The large number of typical alkaline minerals in the second member of Fengcheng Formation in Hashan area reveals the development of another lake basin center in addition to the Mahu Sag. During the deposition of the first member of Fengcheng Formation (P1f1), the lake level was relatively higher, the water salinity was low, the climate was semi-arid, and volcanic sedimentation was developed, with lithofacies mainly composed of organic-rich blocky tuffaceous limestone. In the lower part of the second member of Fengcheng Formation (P1f2), the basin began to shrink, the climate became relatively drier, the water became saltier, the environment became more limited, and the lithofacies were mainly organic-rich layered dolomitic mudstone. In the top of the P1f2 and the lower part of the third member of Fengcheng Formation (P1f3), the environment was relatively closed, the water salinity was higher, a large number of alkaline minerals were developed, and the lithofacies were mainly organic-rich layered alkaline dolomitic mudstone and organic-rich layered mixed shale. In the upper part of P1f3, the input of terrigenous debris increased, salinization weakened, a fan-delta system was developed, and the lithofacies were mainly organic-rich blocky fine sandstone. The sedimentary environment of the Fengcheng Formation has a controlling effect on organic matter enrichment. Overall, a deep-water environment with less input of debris, warm and humid conditions, and relatively lower salinity is more conducive to organic matter enrichment.

国家自然科学基金项目 42172149;国家自然科学基金项目 U2244209;中国石化科技部项目 P21077-1;中国石化科技部项目 P22132

https://doi.org/10.11781/sysydz202304693