鄂尔多斯盆地陇东地区延长组长9烃源岩展布与潜力评价

Distribution and potential evaluation of the source rocks of the Chang 9 Member in the Longdong area,Ordos Basin

为明确鄂尔多斯盆地陇东地区延长组长9烃源岩的勘探潜力,应用有机地球化学方法,结合烃源岩沉积相平面展布特征,开展陇东地区长9烃源岩的烃源岩分相带差异性、地球化学特征及生烃强度研究。结果表明:长9烃源岩普遍发育暗色泥岩,平面展布呈现“沟谷相间”特征,受沉积相控制较为明显。陇东地区长9烃源岩具有较高的有机质丰度,有机质类型以Ⅱ_(1)—Ⅱ_(2)型为主,处于成熟—高熟阶段,整体为中等—好的烃源岩,且长91烃源岩品质优于长92烃源岩。长91烃源岩具有一定的生烃潜力,可以为长8—长9—长10储层供烃,且长9烃源岩生烃强度总体呈现出由南西向北东方向增强的趋势。研究区东北部华池—白豹井区长9烃源岩品质好,生烃强度高,且与附近储层具有较好的运移通道,是该地区长9段石油勘探的有利区。

To clarify the exploration potential of the source rocks of Chang 9 Member of Yangchang Formation in the Longdong area,Ordos Basin,this article conducted a comprehensive study on the differences in source rock facies zones,geochemical characteristics,and hydrocarbon generation intensity of the Chang 9 source rock in the Longdong area based on organic geochemical and the distribution of source rock sedimentary facies,pro⁃viding a basis for further exploration in the region.The results show that the Chang 9 Member is generally devel⁃oped with dark mudstone,and the planar distribution shows a“gully-interlaced”feature,which is more obvious under the control of sedimentary facies;the Chang 9 source rocks in the Longdong area have high organic mat⁃ter abundance,and organic matter types are mainly Ⅱ_(1)-Ⅱ_(2),which are at mature-highly mature stages.Overall,it is a set of medium-good hydrocarbon source rock.Moreover,the quality of Chang 91 source rock is better than that of Chang 92.Chang 91 source rock has certain hydrocarbon generation potential and can supply oil to the Chang 8-Chang 9-Chang 10 reservoirs.The hydrocarbon generation intensity of Chang 9 Member generally shows an increasing trend from southwest to northeast.The Huachi-Baibao area in the northeast part of the study area has good quality Chang 9 source rocks with high hydrocarbon generation intensity and good migration channels with nearby reservoirs,which is a favorable area for Chang 9 Member petroleum exploration in the re⁃gion.