Delta Sedimentary Model Of Shanxi Formation In Qingyang Gas Field, Ordos Basin

Qingyang gas field is a new exploration tight sandstone gas field in the southwest of Ordos Basin, with characteristics of thin production layer, low physical property of reservoir, Shan 1 member is the main production layer. Based on the analysis of field outcrop observation, core drilling and logging data, the Shan 1 member is divided into three sublayers according to cycle characteristics. Based on stratigraphic division, the sedimentary environment, sediment source and sand body distribution characteristics are defined through mineral petrology analysis, grain size analysis, sedimentary facies marker research and Paleogeomorphology restoration. The controlling factors of high-quality reservoir development were analyzed on the basis of comprehensive sedimentary analysis and structural recovery. During the deposition of the Shan 1 member, the meandering river delta is developed, and the sand body is distributed from southwest to northeast. Four main river channels are developed in the study area. The reservoir is mainly developed in the river bed residence, point bar of delta plain and the mouth bar, underwater distributary channel of delta front. Most of high productivity gas wells are distributed in the updip part of the slope. Sedimentation determines the spatial basis of reservoir formation, structural evolution controlling the migration and accumulation mode and the type of gas reservoir in the stage of hydrocarbon accumulation. The overlapping area of sand body development and the updip part of the slope is the favourable area for the gas reservoir.