新疆巴里坤盆地石炭系油气勘探前景

Exploration prospects of Carboniferous hydrocarbon in Barkol Basin of Xinjiang

巴里坤盆地是夹持于哈尔里克山和麦钦乌拉山之间的小型弧间盆地。盆地构造呈箕状,构造相对较为单一,整体上具北高南低、东西高中间低的特点。盆地发育石炭纪地层,上石炭统主要岩性为灰色、深灰色细砾岩与棕黄色泥岩互层;下石炭统为层状泥质灰岩,间夹灰色细砂岩、杂色细砂岩、泥岩。生油岩丰度较高,为较好—好烃源岩,烃源岩分布受古构造、火山等因素的影响,横向变化大。火山岩带在盆地西南部、东北部呈北西走向分布,火山岩与烃源岩呈互层式或指状式接触,有利于烃源岩热成熟,也有利于油气沿断裂近源、垂向运聚成藏。构造活动与火山岩成藏有较密切的关系,大河构造带位于剩余磁力高值区,显示火山岩发育。石炭系晚期抬升浅埋,有利于火山岩储层的改造,可能是风化型火山岩储层有利发育区。大河构造带晚期的断裂继承性活动有利于油气垂向运聚,构造具有海西期雏形,中晚燕山期进一步加强定型,形成自生自储式储盖组合,是石炭系构造-岩性油气藏形成的有利区域。

Barkol Basin is an interarc basin with small scale,which is located between Karlik Mountain and Maiqinwula Mountain in Barkol County of Xinjiang.It is a half graben-like basin and the structure is relatively single with the structure characteristics of high in the north and low in the south,high in the east and west and low in the middle.The Carboniferous formations are developed in the basin.The main rocks are gray-dark gray granule conglomerate and gray-black mudstone in Upper Carboniferous.The tuff,tuffaceous sandstone and basalt are in Lower Carboniferous.The abundance of source rocks is high with a big variation on plane,which is impacted by ancient structure and volcano.Volcanic rocks and hydrocarbon source rocks contact with interbedded or finger type,that is not only conducive to the thermal maturity of hydrocarbon source rocks,but also to the vertical migration and accumulation.There is a close relationship between tectonic activity and reservoir forming of volcanic rock.Dahe Tectonic Belt is located at high value area of residual magnetic force,displaying the development of volcanic rocks,which are lifted and buried at the late stage of Carboniferous and are propitious to reservoir reformation.It is possible to be the favorable development area of weathered volcanic rock reservoir.The fracture has continuous activity at late stage,which is propitious to vertical migration and accumulation.The structure has Hercynian prototype and is further shaped in middle-late Yanshanian,forming the reservoir-cap combination of self-generation and self-storage.It is the favorable area in which the structure-lithology reservoirs are formed.