基准面旋回层序与油层单元划分关系

THE RELATION OF BASE-LEVEL CYCLE SEQUENCE TO RESERVOIR DIVISION

短期和中期基准面旋回过程中A/S值变化与砂体发育关系的分析表明,具有A1、A2和C2型结构的短期旋回层序最有利于储集砂体的发育,各级次层序界面的上下两侧是有利储集砂体的主要发育位置,而基准面旋回层序的中部通常是泥质盖层或隔、夹层的主要产出位置。针对按基准面旋回层序界面的小层划分方案与传统的油气层四级划分方案存在的矛盾,提出以不同级次湖泛面沉积的泥质盖层或隔、夹层为边界的、跨基准面旋回层序界面的砂体和油层四级划分方案,其中的含油层系、油(层)组、复油层、单油层,分别与长期、中期、短期、超短期基准面旋回有关,但存在半个基准面旋回的相位差。这一划分方案既符合油气藏开发层系的划分原则,在实际应用中也更具有可操作性。

The analysis of the relation of A/S ratio to development of sand bodies in short-term and middle-term base-level cycles shows that short-term cycle sequences with A1、A2 and C2 structural types are the most favorable for sand bodies development, the top and bottom of various grade sequence boundaries are favorable position for sand bodies with good reservoir property, and middle part of various grade cycle sequences is the position of muddy cap and barrier beds. With consideration of contradiction between the classification scheme of individual strata based on sequence boundaries of base-level cycle and the four-grade traditional reservoir division scheme, it is suggested that four-grade division scheme of sandbodies and reservoirs is bounded by muddy cap and barrier beds deposited during various grade flooding, and strides across sequence boundary. The reservoir series, reservoir suite, composite reservoir, and single reservoir are related to long-term, middle-term, short-term, and supper-short-term base-level cycles respectively. This scheme is conformed to the divisional principle of pool development series, and is more operable in practical use.