Analysis of pore structure characteristics of low permeability reservoir with mercury injection data——taking E₂l₃ reservoir in W11-7 oilfield for example

Pore structure is the principal factor influencing the fluid migration and accumulation in microscopic pore of low permeability reservoir, by which, the quality of reservoir can be directly determined.Taking E₂l₃ reservoir in W11-7 oilfield as an example, mercury injection data can be applied to qualitative and quantitative examination of the reservoir pore structure characteristics.The results show that the pore structure can be classified into three types, and characterized by small throats, poor sorting and poor porethroat connectivity, the bad pore structure is the principal factor causing low or super-low permeability of E₂l₃ reservoir.Based on the multiple discriminant analysis method, the displacement pressure, median capillary pressure, max pore-throat radius, mean porethroat radius and sorting coefficient are optimally selected as pore structure classification evaluation parameters, and combining with property parameters, the E₂l₃ reservoirs are classified as types I, Ⅱ and Ⅱ I, and the reservoir of Ⅱ and Ⅲ types is widely developed.