湖相深水细粒沉积岩米兰科维奇旋回及其页岩油勘探意义——以东营凹陷牛页1井沙四上亚段为例  

Milankovitch cycle of lacustrine deepwater fine-grained sedimentary rocks and its significance to shale oil:A case study of the upper Es4 member of well NY1 in Dongying sag

作　　者：孙善勇 刘惠民[2] 操应长[1] 张顺[2] 王勇[2] 杨万芹[2] 

机构地区：[1]中国石油大学(华东)地球科学与技术学院,山东青岛266580 [2]中国石化股份胜利油田分公司勘探开发研究院,山东东营257015

出　　处：《中国矿业大学学报》2017年第4期846-858,共13页Journal of China University of Mining & Technology

基　　金：国家重点基础研究发展规划(973)(2014CB239102);国家科技重大专项(2017ZX05049-004)

摘　　要：以东营凹陷沙四上亚段湖相深水细粒沉积岩为研究对象,综合运用岩心、薄片、测录井、全岩X射线衍射、地球化学元素等资料及频谱分析和小波分析等方法,分析了细粒沉积岩的基本特征,划分了岩相类型,明确了岩相高频旋回成因机制,建立了岩相沉积模式,探讨了米兰科维奇旋回对页岩油勘探的意义.认为东营凹陷沙四上亚段细粒沉积岩发育多种岩相类型,并且记录了稳定的米兰科维奇旋回,岩相旋回性变化主要受控于偏心率和岁差参数,纹层状岩相层偶形成与四季气候变化有关,长偏心率旋回周期分为干冷气候半周期和暖湿气候半周期,暖湿气候半旋回背景下的岁差旋回中期附近地层单元是页岩油勘探的优选层段.研究结果表明:东营凹陷沙四上亚段细粒沉积主要发育8种岩相类型;长偏心率、斜率和岁差周期造成的地层旋回厚度分别为39.4m,3.0~5.2m以及1.7~2.4m,牛页1井沙四上亚段共记录了4个长偏心率旋回和84个21.9ka岁差旋回,堆积速率介于84.47~146.20μm/a;暖湿气候半周期背景下的岁差旋回中期主要发育富有机质纹层状泥质灰岩相,是页岩油勘探的最有利层段,通过米兰科维奇旋回可实现页岩油勘探有利层段的预测.Combined with core, thin sections, well logging, whole-rock X-ray diffraction, geo- chemical elements data, spectral analysis and wavelet analysis method, the primary characteris- tics of fine-grained sedimentary rocks of the upper Es4 member of Dongying sag were systematically analyzed. Meanwhile, lithofacies types, the formation mechanism of high frequency cy-cles, depositional model and research significance to shale oil were studied. It is revealed that the upper Es4 member of Dongying sag develops a variety of lithofacies and preserves stable Milankovitch cycles. Variations of lithofacies cycles are controlled by eccentricity and precession. The lamina couplet of lamellar lithofacies are formed in a year and controlled by the four seasons climate change. The long eccentricity cycles can be divided into dry-cold climate semiperiod and wet-warm climi^te semiperiod. The results show that eight lithofacies develop in the fine-grained sedimentary rocks of the study area. The thicknesses of stratigraphic cycles caused by long eccentricity, obliquity, and precession are 39.4 m, 3.0-5.2 m, and 1.7-2. 4 m respectively. There are four long eccentricity cycles and eighty-four 21.9 ka precession Cycles in the upper Es4 member of NY1, with the accumulation rate of 84.47-146.20μm/a. The central stratigraphic unit within a precession cycle under the wet-warm climate semiperiod back-ground is organic-rich lamina argillaceous limestone lithofacies, which is the favorable target for shale oil exploration. It is concluded that the Milankovitch cycles can be used to forecast the optimal beds in shale oil exploration.

关 键 词：米兰科维奇旋回 细粒沉积岩 沉积模式 页岩油 东营凹陷 

分 类 号：TE122[石油与天然气工程—油气勘探]