准噶尔盆地阜东斜坡头屯河组二段沉积微相及主控因素

Sedimentary Microfacies Identification and Controlling Factors of the Toutunhe Formation (2^(nd)Member) in the Eastern Fukang Slope, Junggar Basin

准噶尔盆地阜东斜坡头屯河组是重要的油气勘探目的层。基于岩心、测井及地震等资料,探究研究区的沉积特征及其展布规律,对该区今后油气滚动勘探有重要意义。研究表明:研究区目的层岩性以泥岩、粉砂岩及细砂岩组合为主,总体表现出“泥包砂”的特点;其中砂岩成分成熟度低,具有近物源特征;粒度概率累计曲线主要为跳跃悬浮式,水动力类型为牵引流;测井曲线可分为钟形、箱形和线形3类。综合岩性、粒度、测井及地震反射特征等明确了研究区主要发育曲流河沉积,可识别出曲流河道、点坝、泛滥平原和废弃河道4种沉积微相。研究区沉积物源来自东北方向,曲流河展布特征主要受地形坡度、物源远近及粒度特征影响。曲流河由北东向南西延伸,且西南部的河道弯曲度有增大的特征,河道逐渐呈现网状分布特征,点坝砂体也更加发育;同时,西北部也出现了连片分布的曲流河沉积。因此,后续油气勘探优质储层的找寻应重点考虑西北部与西南部的点坝砂体。

The Toutunhe Formation in Fudong Slope(Junggar Basin) is an important oil and gas exploration target. Based on the core, well logging and seismic data, it is crucial to explore the sedimentary characteristics and distribution patterns in the study area for future prospecting. Our results show that the target strata are mainly composed of mudstone, siltstone and fine sandstone, which generally shows mud-sand inclusion features. The sandstone component has low maturity and proximal provenance. The grain size probability accumulative curve is mainly jump-suspension type, and the hydrodynamic type is traction current. Logging curves can be classified into three types: bell, box and line. Based on lithology, grain size, logging and seismic reflection characteristics, we suggest that meandering river deposits dominate in the study area, and that meandering channel, point bar, flood plain and abandoned channel microfacies can be identified. The sediment source in the study area is from northeast, and the distribution of meandering river was mainly affected by local topography, sediment transport mode, and grain size characteristics. The meandering river may have extended from northeast to southwest. The curve of the channel in the southwest increased, and the channels gradually formed a network, with point bar sand bodies better developed. Meanwhile, there are also contiguous meandering river deposits in the northwest. Therefore, the point bar sand bodies in the northwest and southwest should be considered while searching for high-quality reservoirs in future oil and gas exploration.