乌兰盖盆地下白垩统巴彦花组沉积特征及油气意义

为了深入认识内蒙古东部乌兰盖盆地下白垩统巴彦花组沉积特征及其油气意义,通过野外实测剖面、钻井测井等资料,将乌兰盖盆地下白垩统巴彦花组划分为扇三角洲、辫状河三角洲、湖泊、湖底扇等四种沉积类型。巴彦花组一段沉积时期,盆地周围普遍发育扇三角洲沉积,湖盆面积小,以滨浅湖沉积为主;二段沉积时期,构造活动相对稳定,湖平面缓慢上升,湖泊面积扩大,沼泽相含煤沉积发育,煤层稳定;三段沉积时期,盆地东南部边界断裂活动加剧,湖盆快速沉陷,在盆地南缘发育了扇三角洲沉积,盆地北部则发育了大面积的辫状河三角洲沉积,盆地内部发育了湖底扇沉积;四段沉积时期,构造活动又相对稳定,盆地湖泊面积扩大,发育了较厚的湖相沉积。根据有机地化测试分析结果认为半深湖-深湖亚相和滨浅湖沼泽微相的暗色泥岩和炭质泥岩具有良好的生烃能力,是未来勘探的有利区域,这有可能成为中国东北地区油气产量逐渐减少的一个补充。

Sedimentary Characteristics and Petroleum Geologic Significance of the Lower Cretaceous Bayanhua Formation in Wulangai BasinOu Lihua1 Qian LiJun1 Yi Haisheng2 Zhang Chao3 Xia Guoqing2

In order to in-depth understanding at the significance of oil and gas and sedimentary characteristics to the lower cretaceous in eastern Inner Mongolia Wulangai Basin, Bayanhua Formation is divided into four kinds of sedimentary type include braided river delta, fan delta, sublacustrine fan, lake and so on through analysis field survey section, drilling and well logging data. Alluvial fan deposits were generally developed around the basin during the first depositional stage of the Bayanhua Formation. While in the second sedimentary stage, the tectonic activities were relatively stable, the lake plane was slowly rising, the lake area expanded, the bog facies coal-bearing deposition developed, and the coal beds were stable. While in the third sedimentary stage, the boundary faults in the southeast of the basin intensified and the lake basin sank rapidly. Fan delta deposit developed over the southern edge of the basin, and large area of braided river delta deposit developed in the north of the basin. During the fourth sedimentary stage, the tectonic activities were relatively stable, the area of the lake expanded, and the thick lake deposition developed. According to the results of organic geochemical analysis, dark mudstone and carbonaceous mudstone in semi-deep lacustrine subfacies and swamp microfacies in shallow lacustrine have good hydrocarbon generation ability and oil and gas exploration potential, which maybe a supplement to the incline of the petroleum production in northeast region of China.