准噶尔盆地南缘四棵树剖面八道湾组扇三角洲沉积特征

Sedimentary Characteristics of Fan Delta of the Badaowan Formation, Sikeshu Section,Southern Junggar Basin

在野外露头观察与实测的基础上,运用沉积学与层序地层的相关理论,对准噶尔盆地南缘四棵树剖面八道湾组沉积特征进行了详细研究。该剖面八道湾组为扇三角洲沉积,扇三角洲平原与扇三角洲前缘亚相均比较发育。运用层序地层学中基准面变化的原理,将八道湾组划分为2个长期旋回,并细分为3个中期旋回以及若干短期旋回。总结了露头区八道湾组A/S比值与地层叠加样式之间的响应关系:低A/S比值条件下,易形成连通性好的厚层叠加砂体,沉积微相类型较单一;中A/S比值条件下,易形成单层厚度较薄的、似毯状的、垂向上紧凑叠加的多层状砂体;高A/S比值条件下,泥岩更为发育,而砂体多呈孤立状,呈现厚层泥与薄层砂的沉积特点。通过详细解剖露头剖面八道湾组的沉积特征,最终建立了该区八道湾组扇三角洲沉积模式,为准噶尔盆地南缘扇三角洲油气储层的研究提供了借鉴。

On the basis of observation and measurement in field,and with the application of sedimentology and high resolution sequence stratigraphy theories,a detailed study on the sedimentary characteristics of the Badao-wan Formation in Sikeshu section,southern Junggar Basin has been conducted.The fan delta system developed fan delta plain and fan delta front subfacies,and the sedimentary characteristics of the two kinds of subfacies are concluded.In the outcrop,two long-term stratigraphic cycles are identified and Badaowan Formation can be subdivided into three medium-term cycles,as well as the composition of a number of short-term cycles.This paper summarized the relationship between the A/S ratio with stratigraphic stacking patterns in outcrop area.A thick stacked sand body with good connectivity was formed in the low A/S ratio condition,and the types of sedi-mentary microfacies are single;In the medium A/S ratio condition,thin and blanket-like monolayer superim-posed in vertical,and formed compacted multilayer sand body.Mudstone and isolated sand bodies are deve-loped in the high A/S ratio condition rifely,and their internal structures are compacted with limited lateral ex-tension.Eventually,through detailed anatomy of the sedimentary characteristics of Badaowan Formation in the outcrop section,a fan delta sedimentary model of Badaowan Formation has been established,and provides refer-ence for fan deltas reservoir research in southern margin of Junggar Basin.