| Xishanyao formation petroleum reservoir of Niuquanhu area in Santanghu oilfield is low-porosity, low-permeability and low-pressure. It is indicate very short injection/production cycle, strong contradiction between plane and profile, that see the water soon after the oil well production, poor effects of water flooding and low well yield during the production. In order to improve the dejectiovelopment effect, though the scanning electron microscope, casting slice, image pore and high pressure Hg inn, need to study the reservoir rock characteristics, physical properties, heterogeneity, diagenesis, and micro-pore structure.The Xishanyao formation X2 sublayer of the study area are divided into four small sublayers, from top to bottom are the small sublayers of X21, X22, X23and X24. Sedimentary facies of the reservoir is a fan delta front facies. The main components of sandstone of the study area is lithic debris, followed by quartz and feldspar. The average porosity is 12.5% and the average permeability is 1.44×10-3μm2, so it is a low porosity and low permeability reservoirs. The small sublayers of X22 and X23 relatively have good physical properties, the small sublayers of X21 and X24 relatively have poor physical properties. Diagenesis mainly developed with compaction, cementation, corrosion and a small amount of metasomatism and recrystallization. The layers heterogeneity is relatively weak and the intra-heterogeneity is very strong. The reservoir's layer heterogeneity, intra-and micro-heterogeneity combined effect the surface heterogeneity. Pore type are mainly tuffaceous dissolution pores, intergranular pores, feldspar dissolution porosity, intercrystal pore, and a very small amount of debris dissolution pore and micro-cracks. The X2 sublayer reservoir of Xishanyao formation is divided into three categories. From class one to class three, the reservoir properties are getting bad, and the reservoir capacity and flow capacity variation. |
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