鄂尔多斯盆地长7浊积岩特征及成藏条件分析

ANALYSES ON THE CHARACTERISTICS AND RESERVOIR FORMING CONDITIONS OF CHANG 7 GROUP TURBIDITE IN ORDOS BASIN

利用岩心、测井等资料对鄂尔多斯盆地长7浊积岩特征及成藏条件的分析结果表明，长7油层组沉积层理、沉积构造及砂岩粒度等反映晚三叠世延长组长7沉积时在深湖一半深湖相发育浊积岩。长7浊积岩的电性响应特征表现为自然伽马曲线具有明显的齿化现象，在地震反射剖面上则表现为不稳定沉积、相带变化大等特点。浊积岩储集体的物性条件相对较差，孔隙度平均为8．5％，渗透率平均为0．12×10-3μm2，属超低孔、低渗储层，但由于其紧邻优质烃源岩，成藏条件优越，可大面积成藏。

With the help of the data of cores and well loggings, the characteristics of the turbidite and the condi- tions of the reservoir formation are analyzed for the above group of Ordos Basin. The analyzed results show that the sedimentary beddings, structures, sandstone particles and so on of the reservoir group reflect the deep and semi- deep lake facies developed environments of Late Triassic Yanchang Formation. The response characteristics of elec- trical property of Chang 7 Group turbidite display the obvious toothed phenomenon of GR （ gamma ray） curve, and moreover show the features of the unstable sedimentation and enormous facies changes on the seismic reflection pro- files. The physical conditions of the turbidite accumulating body are relatively poorer, whose average porosity and permeability are respectively 8.5% and 0. 12 ×10-3μm2, belong to ultra-low porosity and low permeability reser- voir. However, for the body is close to the regions with high-quality source rocks and favorable hydrocarbon en- riched conditions, so it can form reservoirs on a large scale.