Sedimentary Microfacies Research On The Permian He8 In Wellblock Shan28 Of Jingbian Gas-field

The main gas-bearing reservoir of Permian in the Jingbian gas field is He8 of the Shihezi Formation.However,the recognition of the sedimentary facies and microfacies in He8 have long been disputed,and these disputes restrict the efficient integration process of exploration and development.On the basis of many previous research results,theories of sedimentary petrology,lithofacies palaeogeography,reservoir geology and sedimentary geochemistry,we consider He8 sand-body as the research object,and redefined the stratigraphic division of the He8 stratum.The source of the parent rock is determined by multi means source analysis,and the study of sedimentary microfacies in He8 is emphatically carried out,and the sedimentary facies model in accordance with this area is established.The following achievements and understanding have been achieved:The cathodoluminescence characteristics of He8 quartz show that the source of the area is mainly derived from metamorphic rock series.It is found that the rock mineral maturity of the area is increasing from north to south,which indicates that the study area is controlled by the nature of the parent rock in the northern source area.The distribution pattern of rare-earth elements is enriched in ?LREE,and the ?HREE is seriously depleted.The above means indicate that the provenance of the study area comes from the same metamorphic rock series in the north,and is presumed to be the source of metamorphic rocks in the North Yinshan.The sedimentary facies of the study area is a delta deposit with the characteristics of shallow water braided river,which can be divided into five types of sedimentary microfacies: distributary channel,heart beach,inter channel,abandoned River and river swamp,respectively.By studying the distribution characteristics of the plane sedimentary facies,it is believed that the sedimentary environment of the 8 section of the two stack in the Shanxi 28 well is the braided river delta plain subfacies,and the braided degree of the braided river is weakened from the bottom to the bottom,and the braided channel evolves from the strong braided channel to the weakly braided channel.