湖相泥页岩天文地层周期及高分辨率沉积旋回测井研究

The mud shale, as the most fine grained clastic sedimentary, formed in a relatively stable sedimentary environment and documented stratigraphic cycles and the depositional cycle information well. The way we using outcrop, rock core or paleontology to divide strata cycle is often limited by sample source, resolution and discontinuity. However, logging in particular FMI has very high resolution (5mm) and continuity, and it carry the depositional cycle information of formation. Therefore, it is very meaningful to carry out the research of analysis quantitatively stratigraphic cycle and sedimentary unit by using logging. We select the palaeogene strata in Bohai Bay basin as the study object. First of all, using core data to classification stratigraphic cycle and sedimentary units of target stratum in the different scales; Secondly, some time-frequency analysis methods for logging and FMI curve, such as Fourier, Wavelet and Blackman–Tukey, will be used to identify stratigraphic cycle, In addition, doing adaptability analysis of each methods and selected parameter value to the scales of stratigraphic cycle and sedimentary units; Then, with the aid of isotopic dating, Paleomagnetic time scales data, to calculate of formation deposition rate, and turn stratigraphic cycles from depth domain to time domain, and make a compare with Milankovitch cycles, and in order to establish the conversion relations between well logging and formation age. Eventually, forming a set quantitative analysis methods of high resolution stratigraphic cycles and sedimentary units based on logging data and provides the scientific basis and a new train of thought for studying high resolution sedimentology and shale oil and gas exploration.

泥页岩作为碎屑沉积的最细粒部分形成于相对稳定的沉积环境，较好地记录了天文地层周期及沉积旋回信息。利用露头、岩芯、古生物划分地层旋回往往受样品来源、分辨率及不连续性的限制，而测井尤其是FMI达到5mm高的分辨率，能有效显示泥页岩的旋回变化。本项目选取济阳坳陷沙河街组泥页岩地层，首先利用岩芯资料划分目的层的天文地层周期及沉积旋回，构建不同尺度沉积旋回叠加信号的正演模型，模拟其频谱特征；其次采用傅立叶、小波和Blackman-Tukey等时频分析方法对测井、FMI数据进行多尺度沉积旋回识别，结合数值模拟规律分析每种方法、参数值等对沉积旋回尺度的适应性；然后借助同位素测年、古地磁时间尺度等资料，计算地层沉积速率，将地层从深度域转换到时间域，并与（亚)米氏周期对比，确立测井与地层年代的转换关系。最终形成湖相泥页岩天文地层周期及高分辨率沉积旋回测井识别方法，为细粒沉积学及页岩油气勘探开发提供科学依据。

本项目以济阳坳陷沙河街组泥页岩地层为对象，运用精细的岩芯描述资料划分天文轨道周期及沉积旋回；通过测井数据建立不同尺度沉积旋回叠加信号的正演模型并模拟频谱特征；运用频谱分析、短时傅里叶变换、小波变换、功率谱估计等时频分析方法对常规测井FMI数据进行多尺度沉积旋回识别，在此基础上，分析每种时频分析方法及参数值识别不同尺度沉积旋回的适应性；借助Re-Os测年及古地磁时间尺度等测年数据，在识别研究层段天文旋回的基础上，通过高精度天文旋回格架等时旋回地层对比，计算地层沉积速率，将地层从深度域转换到时间域，并与（亚)米兰科维奇旋回对比，确立测井与地层年代的转换关系。本项目从岩芯与测井相结合的角度出发，综合经典层序地层学、高频层序地层学和高分辨率层序地层学及米兰科维奇旋回理论，探究了湖相泥页岩天文地层周期及高分辨率沉积旋回测井识别方法，为细粒沉积学的发展提供了一个方向，也为页岩油气勘探开发提供了科学依据。