西昆仑山前地区白垩系分布研究

白垩系是西昆仑山前地区最重要的储层,受区域构造演化控制,其岩性与分布在纵、横向上均发生变化。下白垩统为冲积扇辫状河相沉积的红色砾岩、砂岩夹泥岩;上白垩统英吉沙群在研究区西部为一套海相碳酸盐岩地层。白垩系在喀什凹陷最厚,往西、往东、往北均逐渐变薄,并发生相变与尖灭,控制储层发育。本文在研究区域首次通过地震相研究,根据白垩系反射特征精细追踪对比其层位,确定尖灭位置,进而确定白垩系分布范围。研究认为,地震相能在区域上宏观地反映白垩系的沉积特征与分布范围,进而指导油气勘探,具有很重要的现实意义。

Distribution of the Cretaceous strata in the piedmont area of the Western Kunlun Mountains, Xinjiang

The Cretaceous strata occur as the most important hydrocarbon reservoirs in the piedmont area of the Western Kunlun Mountains, Xinjiang. The Lower Cretaceous strata consist of alluvial fan-braided stream red conglomerates and sandstones intercalated with mudstones. The Upper Cretaceous strata in the Yengisar Group are composed of marine carbonate rocks. These Cretaceous strata occur in the maximum thickness in the Kashi depression, and become progressively thiner and even pinching out westwards, eastwards and northwards. The seismic facies analysis is presented in the present paper for the first time to trace and correlate stratigraphic horizons, and delineate the extent of the Cretaceous strata. The seismic facies may well mirror the macroscopic features and distribution of the Cretaceous strata, and thus have realistic implications for the hydrocarbon exploration in the study area.