石油学报 ›› 2025, Vol. 46 ›› Issue (7): 1308-1326.DOI: 10.7623/syxb202507006

• 地质勘探 • 上一篇    

准噶尔盆地玛湖凹陷北斜坡带风城组沉积特征及古环境演化

冯允献1,2, 唐勇1,3, 秦志军1, 杨森1, 周圆全4, 阿布力米提·依明1,3, 王维1, 白雨1   

  1. 1. 中国石油新疆油田分公司勘探开发研究院 新疆克拉玛依 834000;
    2. 中国石油大学(华东)地球科学与技术学院 山东青岛 266580;
    3. 中国石油新疆油田分公司 新疆克拉玛依 834000;
    4. 中国石油勘探开发研究院 北京 100083
  • 收稿日期:2025-01-22 修回日期:2025-06-06 发布日期:2025-08-08
  • 通讯作者: 唐勇,男,1966年5月生,2009年获西南石油大学博士学位,现为中国石油新疆油田分公司首席专家、教授级高级工程师,主要从事地质综合研究与风险勘探工作。Email:tyong@petrochina.com.cn
  • 作者简介:冯允献,女,1982年5月生,2022年获中国科学院大学博士学位,现为中国石油新疆油田分公司勘探开发研究院博士后,主要从事沉积储层研究工作。Email:fengyuxnian_198205@163.com
  • 基金资助:
    新疆维吾尔自治区天山英才-科技创新领军人才支持项目“北疆地区二叠系超级盆地全油气系统地质理论研究与战略接替领域优选”(2022TSYCLJ0070)和中国石油天然气股份有限公司前瞻性基础性研究科技重大项目“准噶尔盆地二叠系全油气系统地质理论与勘探实践”(2021DJ0108)资助。

Sedimentary characteristics and palaoenvironmental evolution of Fengcheng Formation in the northern slope zone of Mahu sag, Junggar Basin

Feng Yunxian1,2, Tang Yong1,3, Qin Zhijun1, Yang Sen1, Zhou Yuanquan4, Ablimit Yiming1,3, Wang Wei1, Bai Yu1   

  1. 1. Research Institute of Exploration and Development, PetroChina Xinjiang Oilfield Company, Xinjiang Karamay 834000, China;
    2. School of Geosciences, China University of Petroleum, Shandong Qingdao 266580, China;
    3. PetroChina Xinjiang Oilfield Company, Xinjiang Karamay 834000, China;
    4. PetroChina Research Institute of Petroleum Exploration and Development, Beijing 100083, China
  • Received:2025-01-22 Revised:2025-06-06 Published:2025-08-08

摘要: 玛湖凹陷二叠系风城组是准噶尔盆地的主力生油层系,其在早二叠世为典型的碱化湖泊环境。选取玛北斜坡带X203井作为主要研究对象,通过岩心、岩石薄片观察来识别风城组内部的岩相填充与组合模式,划分了沉积体系域,并结合地球化学分析结果恢复了沉积古环境,建立了风城组的沉积演化模式,分析了烃源岩的发育机理。研究结果表明:风城组包括1.5个三级旋回,其中,湖侵体系域(TST)由下至上依次发育三角洲前缘亚相、浅湖亚相、半深湖亚相沉积,最大湖泛面(MFS)发育深湖亚相水平纹层泥岩,湖退体系域(RST)的水体变浅,由半深湖亚相过渡至滨/浅湖亚相。结合热演化、氧化还原、盐度、气候以及生产力等地球化学指标分析认为,风城组沉积的湖水环境演化分为P1、P2、P3共3个阶段。P1阶段为湖侵初期,风城组沉积水体的盐度较低,之后受水解反应影响,湖水逐渐咸化;P2阶段,风城组沉积水体为弱还原环境,同时由于持续的水解作用和干燥的气候条件,湖水的盐度在此阶段最高并在湖盆形成碱矿沉积;P3阶段对应风城组水体的相对湖平面持续下降,但气候变化导致淡水注入量增加,使得湖水的盐度下降并呈氧化环境。整体而言,风城组在P2阶段的咸化、低能水体促进了嗜盐微生物发育,为优质烃源岩的形成提供了物质基础;其次,P2阶段较深水体的还原环境使得有机质得以有效保存,是风城组烃源岩形成的必要条件。

关键词: 准噶尔盆地, 玛湖凹陷, 二叠系, 风城组, 沉积特征, 古环境, 沉积模式

Abstract: The Permian Fengcheng Formation of Mahu sag is the main oil-yielding stratum in Junggar Basin. It deposited in a typical alkaline lacustrine environment during Early Permian. The study targets at Well X203 in the northern slope zone of Mahu sag. Through core and rock thin section observations, the lithofacies filling and association patterns in Fengcheng Formation were identified, depositional system tracts were divided into several types, and the paleo-depositional environment was reconstructed based on geochemical analysis results. Further, a sedimentary evolution model for the Fengcheng Formation was established, and the development mechanism of hydrocarbon source rocks was analyzed. The results indicate that Fengcheng Formation comprises one and a half three-order stratigraphic cycles. Specifically, a vertical succession from delta front subfacies to shallow lacustrine subfacies, and finally to semi-deep lake subfacies is developed from base to top in the transgressive systems tract (TST). The maximum flooding surface (MFS) is marked by deep-lake subfacies horizontal laminated mudstone. In the regressive systems tract (RST), a transition from semi-deep lake subfacies to shore-shallow lake subfacies occurred as the water gradually shallowed. Based on an integrated analysis of geochemical indicators including thermal evolution, redox state, salinity, and productivity, it is suggested that the lacustrine environment evolution process can be divided into three phases (P1, P2 and P3). Phase P1 refers to the initial transgression phase, in which the depositional water body exhibited relatively low salinity, followed by gradual salinization due to the hydrolysis reaction. During Phase P2, Fengcheng Formation was deposited in a suboxic aquatic environment, where the water salinity reached the highest level and the alkaline minerals were precipitated in the basin under continuous hydrolysis and arid climate. Phase P3 was characterized by a persistent decline in the relative lake level corresponding to the depositional water body in Fengcheng Formation. However, the enhanced freshwater influx driven by climate changes reduced the lake water salinity, thus forming an oxic environment. Overall, the saline and low-energy lacustrine conditions in Phase P2 promoted the proliferation of halophilic microorganisms, thus providing a basis for the formation of high-quality source rocks. Furthermore, the suboxic-anoxic conditions in relatively deep water of Phase P2 facilitated effective organic matter preservation, which is an essential prerequisite for the development of source rocks in Fengcheng Formation.

Key words: Junggar Basin, Mahu sag, Permian, Fengcheng Formation, sedimentary characteristics, palaeoenvironment, depositional model

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