拟古水深恢复法研究及在东非裂谷地层划分中的应用

Pseudo paleo-water depth curve recovery approach study and application in EARS

东非裂谷系具有发育晚、地层新、演化时间短和正在演化的特点,造成古生物定年无法满足本区地层划分的精度要求。另外,河湖相砂泥岩互层地层缺乏区域标志性特征,造成岩电特征无法为全区地层统一划分提供有效的依据。由此给该区后续成藏研究带来巨大挑战。对此笔者根据正在演化的裂谷盆地构造控沉积的特点,这一特点使整个湖盆水深变化具有统一的规律,提出了“拟古水深恢复方法”,即以沉积研究为基础,在岩心、岩屑观察过程中,确定湖盆古水深相对变化规律,建立地震相对水深相,统一了湖盆地层划分、确定了各期地层的空间展布。进而反推出Albert湖盆短暂的构造、沉积演化与成藏历史,最后在湖盆的地层发育、构造沉积演化、成烃和成藏规律认识方面取得突破性进展。以此为指导在本区油气勘探实践过程中已经取得了巨大的成功。

Aimed at the characteristics of EARS that is later evolution, younger sediments, shorter time of development and their effects to reservoir formation, according to tectonic controlling sediment character of acting rift, put forward a new approach to research the reservoir formation of EARS, i.e.Based on the deposition research results, through observing core and cuttings to identify the paleo-water depth variation and build relative seismic water depth facies, unify the correlation of well and distribution of oil in the basin. Then retrieve the tectonic, deposition evolution and reservoir formation history. Put forward the potential area of EARS that is good quality reservoir facies tract along the updip direction of structure surrounding the prototype depression to successfully guide many oil and gas discoveries.