子长油田余家坪矿区上三叠统延长组沉积环境

余家坪矿区是子长油田的主要产油区,本文在充分调研的基础上研究了该区的地层划分情况、沉积环境与沉积相以及沉积演化过程,研究结果认为子长油田余家坪矿区地层平缓西倾,全区构造简单,未见有规模的断裂、褶皱出现。该区上三叠统延长组具有长1、长2+3、长4+5及长6油层组,在古气候及构造运动共同影响下,晚三叠世沉积演化经历了湖泊三角洲、曲流河、辫状河、曲流河道交织河的演化历程,形成了一套以河流沉积为主的沉积体系,包括混合载荷弯度河,富砂低弯度河,悬移载荷低弯度河。

Yujiaping Area of Zichang Oilfield is the main oil producing area in Zichang oilfield. Based on the ample investigation, we study the stratigraphic classification, depositional environment and the process of depositional evolution. It is considered that the strata of Yujiaping Area, Zichang Oilfield incline gently to the west. The structure of the whole area is simple without large-scale fractures and folds. Yanchang Group, Upper Triassic consists of Ch1, Ch2＋3, Ch4＋5 and Ch6 Oil Formation in this area. Based on the co-effect of the paleoclimate and tectonic movement, the sedimentary evolution of Upper Triassic experiences lake delta, meandering river, braided river and meandering channel interlacing river, forming a set of depositional system mainly composed of fluvial deposit including mixed load bending river, rich sand low-bending river and suspended load low-bending river.