STUDY ON THE CORRELATION BETWEEN OCCURRENCE CHARACTERISTICS OF MOVABLE FLUIDS AND MICROSCOPIC PORE STRUCTURE OF CHANG 8 FORMATION RESERVOIR IN CENTRAL ORDOS BASIN

The study of movable fluids in low permeability reservoir has a very important role for oil recovery. On the basis of the rock thin section observation, scanning electron microscopy observation, constant speed mercury penetration and nuclear magnetic resonance technology, microscopic pore structure and movable fluids occurrence characteristics of Chang 8 oil layer are studied. The results indicate that the reservoir is mainly composed of fine grain feldspar sandstone and lithic arkoses sandstone, and the interstitial materials are mainly carbonate minerals and clay minerals. The pore types of the reservoir mainly include intergranular pore and feldspar corrosion pore. The reservoir can be divided into two categories: mercury injection expulsion pressure<0.5Mpa with right peak nuclear magnetic T-2 spectrum; mercury injection expulsion pressure >0.5MPa with left peak nuclear magnetic T-2 spectrum. The sorting coefficient, median radius and maximum pore throat radius have a positive influence on the porosity of movable fluids.