Lithological-electrical Parameters and Quantitative Evaluation Criterion of Shaly-sandstone Water-out Reservoirs with Low Porosity and Permeability

Archie equations were the empirical ones established on the basis of pure sandstones with high porosity and permeability,and in which porosity exponent m and saturation exponent n are considered to be constant for oil saturation calculation of pure sandstones.However,m and n were not only related to porosity,also related to formation water resistivity and cationic exchange capacity of shaly-sand reservoirs with low permeability.L Oilfield outside Daqing Oilfield was a typical one with low permeability.Based on litho-electrical experiment,the method for determining m and n values is studied,an empirical model of m and n values is established,models of water-out reservoirs including formation water resistivity,oil saturation and water cut are studied,and based on the study,quantitative evaluation standards are established for the water-out reservoirs.Comparing with actual production data,the technique is used with better effect,and a guidance is provided for oil production at the late stage of L Oilfield.