Study On Oil-Water Flow Law And Development Affecting Factors Of Complex Lithology Carbonate Reservoirs

Complex lithologic carbonate reservoirs are different from conventional sandstone reservoirs.The reservoirs include a variety of lithologies such as dolomite,limestone,and sandstone.The microscopic pore-throat structure is very complex and the heterogeneity is strong,which makes different geological and development characteristics.This paper focuses on the complex pore-throat structures of carbonate reservoirs,oil and water two-phase flow patterns,and the law of reservoir properties time variation during water flooding.Firstly,this paper takes the typical complex lithologic carbonate reservoirs in the Middle East as the research object,and analyzes the microscopic pore-throat structure and spatial topological characteristics of carbonate reservoirs by comparing sandstone reservoirs with cast thin slice analysis and pore network simulation techniques.Secondly,by analyzing the law of oil-water flow at the pore scale,developing the calculation method of relevant parameters of the displacement process,this paper conducted simulation experiments of oil-water two-phase flow,and studied the characteristics of two-phase flow,and calculated the phase permeability under different oil-water contact angles and different wetting conditions.Thirdly,to research the oil-water distribution law during water flooding process,this paper established a typical carbonate reservoir model,using reservoir properties time variation technology combined with oil-water phase permeability curves.Finally,the influencing factors for the development of complex lithologic carbonate reservoirs in the Middle East are analyzed using reservoir engineering theories,and the development optimization design programs are proposed.In this paper,the water-oil relative permeability curves which are from microscopic flow simulation innovatively are applied to the macroscopic numerical simulation,which successfully explains the phenomenon that the water cut of the target carbonate reservoir rises too fast in the middle of development.The seven major influencing factors in the three major aspects of physical properties and development conditions were analyzed,and an optimization program for encryption of new wells and layer adjustment for old wells was developed.The study results in this paper are hoped to provide theoretical reference for the development of carbonate reservoirs and help the reservoirs to be developed efficiently and reasonably.