基于小波分析的定量层序划分及湖平面变化

Quantitative Sequence Division and Lacustrine Level Change Based on Wavelet Analysis

董火祥 刘景彦 陈兆芹

DONG Huoxiang LIU Jingyan CHEN Zhaoqin

中国地质大学(北京)能源学院, 北京 海淀 100083

School of Energy Resources, China University of Geosciences, Haidian, Beijing 100083, China

长堤地区具有很大的油气分布成藏潜力，但限于该地区复杂的构造情况，层序及沉积等情况不明。为探明该区内层序发育及湖平面变化情况，基于高分辨率层序划分及小波分析定量层序划分的方法，利用测井、录井等资料在长堤地区东营组划分出4个三级层序、10个准层序组及19个准层序，并在测井小波变换分析的基础上绘制出Fischer图解，揭示了长堤地区东营组的可容纳空间的变化，近似反映了研究区相对湖平面的变化趋势。研究表明，研究区内东营组呈现一次大规模的湖退和湖侵，其内部的小规模湖退与湖侵的过程与三级层序相互吻合。SQ期，相对湖平面达到最大值，期间有小规模的湖侵湖退，此后缓慢湖退，在SQ末期达到最低值。SQ期快速湖侵后又快速湖退，维持在相对低值波动，整体上表现为湖盆萎缩，被三角洲平原覆盖。

The paleogene of Bohai Bay Basin has always been an important exploration target, which has great potential for oil and gas distribution and accumulation in Changdi Area. However, due to the complex structural conditions in this area, sequence, sedimentation, and other conditions are unknown. In order to explore the sequence development and lacustrine level change in this area, this paper divides the Dongying Formation in Changdi Area into 4 third-order sequences, 10 parasequence sets and 19 parasequences by means of high-resolution sequence division and quantitative sequence division through wavelet analysis. Fischer diagram is drawn on the basis of logging wavelet transform analysis, revealing the change of the accommodation space of Dongying Formation in Changdi Area, which approximately reflects the relative lacustrine level changes in the research area. The Dongying Formation in the research area shows a large-scale lacustrine regression and lacustrine transgression, and the process of small-scale lacustrine transgression and lacustrine regression within the Dongying Formation is consistent with the third-order sequence. In SQ period, the relative lake level reached the maximum, during which there was a small-scale lake invasion and lake retreat, and then slowly lake retreat, reaching the minimum at the end of SQ. During SQ period, the lake transgressed rapidly and then retreated rapidly, which fluctuated at a relatively low value. On the whole, the lake basin shrank and was covered by the delta plain.

10.11885/j.issn.1674-5086.2021.08.30.02