关键词: 微裂缝性特低渗透油藏, 渗透率, 喉道半径, 微观均质系数, 相对分选系数, 可动流体体积百分数, 压敏效应

Abstract: The features of pore space,throat radius,microcosmic uniformity coefficient and relative sorting coefficient of micro-fractured ultra-low permeability reservoir were compared with those of non-fractured ultra-low permeability reservoir under the condition of same permeability.The effects of porous microstructure features on porosity and permeability,volume percentage of mobile fluid and pressure sensitivity were also analyzed.The results showed that the throats of micro-fractured ultra-low permeability cores were connected each other mainly by micro-fractures,and the communication of throats was lower.The micro-fractures had the essential contributions to the micro-fractured ultra-low permeability reservoirs during the flow event.The permeability of reservoirs was correlated tightly with the width of micro-fracture,microcosmic uniformity coefficient,sorting coefficient and volume percentage of mobile fluid in the power law equation.The relationship between porosity and permeability was poor;and the ratio of permeability measured by gas to the permeability measured by water was larger.The heterogeneity,anisotropy and pressure-sensitive effect were all strong.The lower permeability is one of the apparent characteristics of low-permeability reservoirs.The reservoir characteristics of low permeability reservoirs should be synthetically evaluated on the basis of microstructure features of pores,volume percentage of mobile fluid and pressure-sensitive effect.

Key words: micro-fractured ultra-low permeability reservoir, permeability, throat radius, microcosmic uniformity coefficient, relative sorting coefficient, volume percentage of mobile fluid, pressure-sensitive effect