Based on the data of the heavy mineral

core

logging and physical

we studied the sedimentary microfacie reservoirs

'

characteristics of the upper reservoir of the lower Gangchaigou formation in eastern Lenghu region. The results show that during the deposition period

the area is close to the source

and the developed raided river delta plain

sandstone type is mainly composed of feldspar lithic sandstone and lithic feldspar sandstone

and its composition and structure maturity are low. The main pore types of the reservoir are the residual intergranular pores

and the grain size is positively correlated with the porosity and permeability. According to the reservoir classification standard

the reservoir area is divided into three types

most of which not only belong to reserv

oir Ⅱ and Ⅲ with low porosity and permeability

but also belong to medium and low porosity-low permeability reservoirs with strong heterogeneity. The physical properties of reservoirs in the study area are related to the hydrodynamic forces at the time of the sedimentation. The high quality reservoirs are mainly distributed in thick sand bodies with braided river delta distributions.