鄂尔多斯盆地城华地区长3油组高分辨率层序地层学分析

运用高分辨率层序地层学的基准面旋回原理,以钻井、测井资料的综合研究为基础,对鄂尔多斯盆地城华地区长3油层组进行高分辨率层序地层学分析,将其划分为超短期、短期和中期3个级次的基准面旋回层序.各级基准面旋回可进一步分为向上"变深"和向上"变浅"非对称型与对称型两大类3种基本层序类型和更多的亚类型.重点论述了超短期基准面旋回层序沉积背景、叠加式样和沉积动力学过程.在研究超短期和短期旋回叠加和分布规律的基础上,总结出短期基准面旋回的分布模式.研究表明自水下分流河道向河口坝中期基准面旋回层序结构稳定的变化规律,与处于三角洲强烈进积期的长3油层组沉积演化特征是一致的.

Analysis of high-resolution sequence stratigraphy for Chang 3 oil reservoir set in Chenghao-Huachi Oilfield,Ordos Basin

On the basis of a comprehensive study of core and logging data,the high-resolution sequence stratigraphic characteristics of Chang 3 oil reservoir set in the studied area are analyzed according to the base-level cycle principle of high-resolution sequence stratigraphic theory.It is held that the oil reservoir set may be divided into three grades of base-level cycle sequences ——super-short term,short term and medium term cycle sequences.Each grade base-level cycle can be further divided three basic sequence types of up-deepening unsymmetrical sequences,up-shallowing unsymmetrical sequences and symmetrical sequences from up-deepening to up-shallowing and more subtype sequences.The sedimentary environment,superposition styles and sedimentary dynamic process of the super-short term base-level cycle sequences are emphatically discussed.The distribution mode of the short-term base-level cycles is generalized based on the research of the superposition and distribution regularities of super-short-term and short-term base-level cycles.It is shown that the superposition and distribution of the medium-term base-level cycles from underwater branch channel to river mouth bar have stable regularities,which is identical to the sedimentary evolution feature of the Chang 3 oil reservoir set deposited in delta transgressive.stage.