摘要
应用印模法恢复了鄂尔多斯盆地前侏罗纪古地貌形态。区内古地貌格局由“三斜坡、三河谷、两河间丘和一梁”组成,即姬塬东斜坡、定边斜坡、靖边斜坡,宁陕河谷、蒙陕河谷、甘陕河谷,吴旗河间丘、金鼎河间丘和新安边梁。前侏罗纪古地貌控制着下侏罗统延安组早期沉积。延10段属河流沉积环境,发育的沉积微相有主河道、支流河道、河漫滩、河漫沼泽。延9段沉积环境为三角洲到湖泊沉积环境,沉积相主要由三角洲平原亚相、三角洲前缘亚相组成,沉积微相以分流河道、分流间洼地、水下分流河道和分流间湾为主。同样性质的古地貌单元所处的沉积环境不同,必然造成储集砂体形态特征及分布规律的变化,进一步影响油藏的形成和分布。古地貌油藏的形成除受油源、圈闭等基本条件制约外,古地貌-沉积组合和油气运移通道也是形成不同类型古地貌油藏的重要条件。依据已探明油田的空间分布结合古地貌、上覆地层沉积环境、砂体展布、运移通道类型等多种因素归结出定边-吴旗地区古地貌油藏三种成藏模式,即斜坡区-三角洲平原组合成藏模式、河间丘区-三角洲前缘组合成藏模式和斜坡区-三角洲前缘组合成藏模式。
The palaeogeomorphic form of the pre-Jurassic was reconstructed by the method of mold. The palaeogeomorphic units in the study area include three slopes, three river valleys, two mounds and one ridge, i.e., the East Jiyuan slope, Dingbian slope and Jingbian slope ; the Ganshaan river valley, Ningshan river valley and Mengshan river valley; the Wuqi mound and Jinding mound; and the Xin'anbian ridge. The early deposition of Yan'an Formation was controlled by the pre-Jurassic palaeogeomorphic features. In the period of Yan 10 deposition, the sedimentary environment was fluvial, and the microfacies were mostly primary channels, distributary channels, overbank deposit and overbank swamps. In the period of Yan 9 deposition, the sedimentary environment was delta-lacustrine, the subfacies were mostly delta plain and delta front, and the microfacies were distributary channels, inter-channel depressions, underwater channels and inter-channel bays. The palaeogeomorphic units of the same characters, owing to their different sedimentary environments, boundly lead to the change of forms and distribution patterns of reservoir sandbodies, which will make great influence on the formation and distribution of the oil reservoirs. The formation of palaeogeomorphic oil reservoirs is mostly restricted by the source of the oil and traps. The palaeogeomorphic sedimentary combination and migration channels are also the major conditions of forming different types of palaeogeomorphic reservoirs. Three palaeogeomorphic reservoir models, i.e. the slope-delta plain combination, mound-delta front combination and combination of slope-delta front, have been generalized in Dingbian-Wuqi area on the basis of the distribution of the oilfields, the palaeogeomorphic features, the deposition environment of overlying formation, sandbody distribution and migration channels.
出处
《古地理学报》
CAS
CSCD
2003年第4期497-507,共11页
Journal of Palaeogeography：Chinese Edition
关键词
鄂尔多斯盆地
前侏罗纪
古地貌
油藏
沉积环境
斜坡
河谷
河间丘
Ordos Basin, pre-Jurassic, palaeogeomorphic features, sedimentary environments, slope, river valley, mound, ridge, oil reservoir
