Abstract: The deep series of strata in Anpeng oilfield of Biyang depression is as the major explorative horizon at present by Henan Petroleum Exploration Bureau. Study of its reservoir characteristics and controlled factors is of great significance for exploration and development of this oilfield. The lower sub-member of No.3 member, Hetaoyuan formation of Paleogene belongs to fan delta deposits with buried depth of over 2 800m. The reservoir pore space mainly consists of intergranular pore, solution pore and fracture, dominated by residual intergralar pores and solution pores. Slim throat, micro-throat, poor throat connectivity and serious heterogeneity make it become a typical reservoir with low porosity, low permeability to extra low permeability. The variation of reservoir petrophysical property is primarily controlled by sedimentary facies, diage-nesis and structure in it. The best facies of reservoir capacity is the fan delta, lhose of others like distal sandbar, frontal sand sheet and proximal underwater distributary channel are poor. Secondary solution pores are generally found in B epoch of late diagenesis; fractures occurs on axis of the anticline, seldom on sides.

Key words: Biyang sag, reservoir characteristic, sedimentary facies, diagenesis