层序界面控制下差异早成岩作用对碳酸盐岩储层的影响
——以伊拉克R油田Mishrif组为例

Effect of differential early diagenesis controlled  by sequence boundary on carbonate reserviors:a case study of Mishrif Formation in R Oilfield, Iraq

毛先宇 宋本彪 田昌炳

中国石油国际勘探开发有限公司，北京 100034 中国石油勘探开发研究院，北京 100083

China National Oil and Gas Exploration and Development Company Ltd., Beijing 100034, China Research Institute of Petroleum Exploration and Development, PetroChina, Beijing 100083, China

通过R油田多口取心井岩心、薄片、碳氧同位素、测井曲线等资料的综合分析，厘清了Mishrif组碳酸盐岩不同级别、不同类型层序界面的识别特征，以及在层序界面控制下早成岩作用对储层的影响。研究表明：R油田Mishrif组属于二级层序海退半旋回上部，可细分为1.5个三级层序（S1，S2）及5个四级层序（FS1—FS5）。其中，三级层序S1为一个海退半旋回，S2为一套完整的海进海退旋回，其顶界同为二级层序界面。识别了3种四级层序界面类型，分别为中期地表暴露型、短期地表暴露型和水下硬底型，三级层序界面为中长期间歇暴露硬底型，二级层序界面为长期地表暴露型。不同类型层序界面沉积与早成岩特征各不相同，造成了油藏内部结构和储层品质的变化。因此，层序格架建立及其层序界面差异早成岩特征研究可为储层成因分析与油藏地质建模提供基础。

Through the comprehensive analysis of the data of cores, thin slices, carbon and oxygen stable isotopes and logging curves of several coring wells in R Oilfield, this paper clarifies the identification characteristics of different levels and types of carbonate sequence boundaries in Mishrif Formation and the effect of differential early diagenesis controlled by sequence boundary on reservoirs. The research results show that the Mishrif Formation of R Oilfield is located in the upper part of the second?鄄order sequence retrogression semi?鄄cycle, which can be subdivided into one and a half third?鄄order sequences (S1, S2) and five fourth?鄄order sequences (from FS1 to FS5). The third?鄄order sequence S1 is a regressive semi?鄄cycle, S2 is a complete cycle and its top boundary is the boundary of the second?鄄order sequence. Three types of the fourth?鄄order sequence boundary are identified, which are mid?鄄term surface exposure type, short?鄄term surface exposure type and submarine hardground type respectively. The third?鄄order sequence boundary is mid?鄄long term intermittent exposure hardground type, and the second?鄄order sequence boundary is long?鄄term surface exposure type. The sedimentary and early diagenetic characteristics of different types of sequence boundaries are different, resulting in changes in  inner structure and quality of the reservoir. Therefore, the establishment of sequence framework and the study of differential early diagenetic characteristics controlled by sequence boundary can provide a basis for reservoir genetic analysis and geological modeling.

10.6056/dkyqt202203010