滨里海盆地碳酸盐岩高频层序特征及其油气勘探应用——以M区块石炭系KT—I含油层系为例

Features and Petroleum Exploration Significance of High-Frequency Sequence in Pre-Caspian Basin:A Case from Carboniferous KT-I Member in M Block

KT—I是滨里海盆地M区块盐下重要含油层系,该层灰泥频繁互层,相带类型多样,非均质性严重,储层展布认识不清。本文应用高频层序地层学研究思路,提出碳酸盐岩高频层序及超层序划分体系域的可行性及思路,以及淹没不整合面作为碳酸盐岩层序界面的重要作用。在此基础上,岩—电—震相结合,通过淹没不整合面和暴露间断面等层序界面的分级识别与分析,首次将研究区KT—I含油层系划分为3个四级层序、9个五级层序,并对高频层序进行体系域划分;建立了研究区快速海侵(对应淹没不整合)和慢速海侵条件下对应的高频层序体系域发育模式,理清研究区地层发育特征及储层展布规律。进而讨论淹没不整合及高频层序体系域在碳酸盐岩油气勘探中的应用。

KT-I is one of the most important oil bearing series in M block of Pre-Caspian basin.The reservoir spreading is not clear understanding with varied types of facies belts,severe heterogeneity and limestone interbedded with mudstone.In terms of high-frequency sequence stratigraphy,the feasibility and thought of tract system division in high-frequency sequence and super sequence is put forward.And the drowning unconformity plays an important part as carbonate sequence boundary.On this basis,by the recognition of sequence boundary,such as drowning unconformity and exposed punctuated surface,KT-I member has been for the first time divided into 3 fourth level sequence and 9 fifth level sequence and the system tract of high-frequency sequence has also been done.The system tract model of high-frequency sequence on rapid transgression（equivalent to drowning unconformity） and slow transgression condition has been established.Then,the developing features of strata and the reservoir spreading in study area have been clear.The application of drowning unconformity and the system tracts of high-frequency sequence in carbonate petroleum exploration has been summarized at last.