准噶尔盆地哈山南缘白垩系清水河组油砂基本地质特征

为了扩大哈山南缘风城油砂山外围的油砂勘探成果,针对白垩系清水河组油砂,以地表地质调查成果为基础,通过对油砂岩露头与岩芯的粒度、岩石薄片、测井、铸体、重量含油率等资料的分析,开展沉积相与储层特征等方面研究。结果表明,清水河组油砂以长石岩屑砂岩、岩屑砂岩为主,砂岩稳定性较差,距离物源较近;清水河组识别出冲积扇、辫状河三角洲、辫状河3种沉积相,细分为9种微相;油砂主要发育于辫状河河道滞留、心滩、三角洲平原分流河道及前缘水下分流河道微相中,油砂岩重量含油率高达35.12%,孔隙度为25.3%~39.1%,渗透率为124~4580 mD,含油性、孔隙度、渗透率均较好,以上4种微相砂体可作为下一步勘探开发的重要方向。丰富的烃源岩、良好的运移通道、优质的储集层及降解稠化作用是哈山南缘油砂成矿的主控因素。该研究成果,对整个准噶尔盆地西北缘油砂勘探具有一定指导意义。

Basic geological characteristics of oil sands of Cretaceous Qingshuihe Formation in the southern margin of Hashan,Junggar Basin

In order to expand the oil sands exploration results outside the Fengcheng Oil Sand Mountain in the southern margin of Hashan,for the oil sands of the Cretaceous Qingshuihe Formation,based on the results of surface geological survey and core of the drilling,through the study of different outcrops and cores,the logging curve,the casting thin sections,oil content by weight and analysis of laboratory data,to carry out research on sedimentary facies and reservoir characteristics.The results show that Qingshuihe Formation oil sandstone are mainly lithic sandstone and feldspar lithic sandstone,which reflects that rock stability of sandstone is in a low degree and fairly close to the source area;The Qingshuihe Formation identified 3 facies,namely alluvial fan,braided river delta and braided river,which were subdivided into 9 microfacies;The oil sand beds are mainly occurred in the midchannel bar sand bodies of braided river,distributary channel in delta plain and subaqueous distributary channel in delta front,the oil content by weight reached 35.12%,and the porosity of oil sands of 25.3%~39.1%,and the permeability of 124~4580 mD,they are thus concluded that oil sandstone have good reservoir quality and oil bearing property.The braided river channel retention,bank,distributary channel in delta plain and subaqueous distributary channel of delta front sandbody can be used as an important direction for further exploration and development.Abundant source rocks,good migration channels,high quality reservoirs and degradation thickening are the main factors for the mineralization of oil sands in the south margin of Hashan.The above results have certain guiding significance for oil sands exploration in the northwestern margin of Junggar Basin.