T-R旋回层序在陆相盐湖盆地中的应用 ——以柴西南英西地区下干柴沟组上段为例

Application of T-R cycle sequence in continental salt lake basin: a case study of Upper Member of Lower Ganchaigou Formation in Yingxi area, southwestern Qaidam Basin

徐彬 李建明 张永庶 崔俊4

中国石油大学（华东）地球科学与技术学院，山东 青岛 266580 长江大学地球科学学院，湖北 武汉 430100 非常规油气湖北省协同创新中心，湖北 武汉 430100 中国石油青海油田分公司勘探开发研究院，甘肃 敦煌 736202

School of Geosciences, China University of Petroleum, Qingdao 266580, China School of Geosciences, Yangtze University, Wuhan 430100, China Hubei Cooperative Innovation Center of Unconventional Oil and Gas, Wuhan 430100, China Exploration and Development Research Institute, Qinghai Oilfield Company, PetroChina, Dunhuang 736202, China

综合分析钻井、测井、岩心等资料，对柴西南英西地区下干柴沟组上段进行了层序界面识别及层序特征分析，在此基础上建立了层序地层格架与层序发育模式，研究了有利储层分布位置。结果表明：层序发育受控于构造运动、古气候变化及湖平面升降；下干柴沟组上段自下而上可划分为2个三级层序，并进一步细分为6个四级层序，各级层序界面主要为岩性突变面，各级层序均发育湖侵体系域与湖退体系域，并均具有快速湖侵、缓慢湖退的特征；SQ3—SQ4表现为早期湖侵、中后期持续湖退，沉积相由半深湖亚相逐渐转变为盐湖亚相，SQ4发育大量岩盐盖层；有利储层主要发育于湖退体系域中部。

Based on the analysis of drilling, logging and core data, the sequence interface was identified, and the characteristics of sequence were analyzed in the Upper Member of Lower Ganchaigou Formation in Yingxi area. On this basis, the sequence stratigraphic framework and sequence development model were established to study the distribution of favorable reservoir. The results show that sequence development was controlled by tectonic movement, paleoclimate change and lake-level fluctuation. The researched formation can be divided into two third-order sequences from bottom to top, and further subdivided into six fourth-order sequences. The sequence interfaces at all orders are mainly lithological mutation surfaces. The lacustrine transgressive system tract(LTST) and lacustrine regressive system tract(LRST) were developed in all orders of sequences; they all have the characteristics of rapid lacustrine transgression and slow lacustrine regression. From SQ3 to SQ4, it shows lacustrine transgression in the early stage and continuous lacustrine regression in the middle-late stage. The sedimentary facies gradually changed from semi-deep lake to salt lake, and a large number of evaporite caprocks developed in SQ4. The favorable reservoirs were mainly developed in the middle of the lacustrine regressive system tract.

10.6056/dkyqt202004002