鄂尔多斯盆地南部延长组浊积岩体系及油气勘探意义

鄂尔多斯盆地南部的浊积岩体系主要发育于三叠系延长组长7、长6油层组。按其沉积特征可分为坡移浊积扇和滑塌浊积扇,前者相带发育相对齐全,垂向上多期互相叠加,可划分为:斜坡—槽道—内扇相、辫状水道、辫状水道间、辫状水道前缘—中扇相、外扇相和盆地平原相,后者多呈透镜状夹于较深湖亚相的深灰色泥岩中,相带分异不明显,仅可分为中心相和边缘相。两类浊积扇主要分布在近源斜坡带及远源末梢斜坡带。滑塌浊积岩主要由阵发性的偶然因素诱发而成,规模相对较小,储集物性较差;而坡移浊积扇则与地形坡度的有利配置和较稳定的物源补给有关,其沉积厚度大,分布广,储集物性好,是深湖区岩性油藏勘探的主要目标。

Turbidite Systems and the Significance of Petroleum Exploration of Yanchang Formation in the Southern Ordos Basin

The tutbidite systems of the southern Ordos basin mainly developed in the Chang 7 and Chang 6 oil-bearing of the Yanchang formation. From its sedimentary characteristic, the turbidite fan could been distinguished and divided into slope-moving turbidity and slide-moving turbidity. The facies belts of slope-moving tuibidity developed correspondingly complete and many times tuibidity current sediment vertically overlapped each other. The facies could been divided into slope-channel-root fans, braided channel, middle braided channel , braided channel front-middle fans, outer fans and basin plain. The slide-moving turbidity that appeared in the deep lake sedimentary only been divided into middle facies and edge facies, and the facies belts hardly distinguished easily. The two turbidity fans mainly distributed on the near-root-slope belts and the far-root-slope belts. The slope-moving tuibidity that sedimentary thickness was thiner mainly induced randomly by occasional factors, and its reservoir quality was correspondingly bad, but the slope-moving turbidity that its sedimentary thickness was thicker and distributed broad was the mainly oil-gas exploration target in the lithologic oilpool. It formed with advantageous slope structure and the steady material source supply.