阿尔及利亚扎尔则油田F4层段地层与储层分布规律

区域构造-沉积演化背景与研究区大量岩心、测井资料分析相结合的沉积相分析表明, 下泥盆统F4层段属于处于陆隆部位的半深海背景下的海底扇沉积.以F4层段中部稳定发育的深海泥岩段为区域对比标志层, 将其分为上部和下部2个旋回, 分别对应2期扇体的形成与发育过程.以各扇体内部较为稳定的泥岩为次级对比标志层, 可进一步将各扇体划分出相当于砂层组级别的地层单元, 由此建立了F4层段具有时间意义的地层对比格架.在分析各扇体沉积亚相类型与成因机制的基础上, 认为F4层段储层成因类型主要包括辫状水道复合体、沉积型水道和水道末段舌状体3种类型.在高精度时间地层格架内, 分析了储集砂体平面展布规律, 并提出F4层段海底扇至少存在来自北西西和东南2个方向的物源供给体系, 属于多点物源和砂质扇成因类型.该研究不仅为重力流沉积层序地层划分和对比提供了研究思路与方法, 同时也为F4层段剩余油的分布研究提供了可靠的地质模型, 为油藏的深入开发挖潜提供了科学依据. 

Stratigraphy and Facies Distribution of Lower Devonian F4 Unit in Zarzaitine Oilfield,Illizi Basin,Algeria

Based on cores and well logs, the analyses of tectono-sedimentary setting and facies show that F4 unit formed by submarine fan located in the continental rise. Lower Devonian F4 unit can be divided into upper cycle and lower cycle by a correlating fan-wide marine mud datum called "middle mud", which correspond individual the two-stage of the submarine fan evolution. Each cycle can be subdivided into several sub-cycles by mudstone or thin bedded siltstone, and mudstone which can be traced in the interior fan, thereby establishing the cronostraticframe of F4 unit. In light of the analysis of subfacies and their mechanisms, the reservoir types of F4 unit include braided channel-complex, sedimentary channel and tongue-like body. Facies distribution maps in the precision stratiraphic framework indicate that the submarine fan sediments formed F4 unit were supplied from at least two sources, i.e., northwest and southeast. The genetic type of F4 unit is a multiple point-source sand-rich fan. This study provides not only correlation strategy of submarine fan, but also a reliable geological model for the further development of F4 unit.