Research On Optimization Of Periodic Water Injection In XC Ultra-Low Permeability Reservoir

The water injection development of the XC ultra-low permeability reservoir has entered the middle and late stage,the water cut rises rapidly,and the production decreases rapidly.As an effective adjustment measure,periodic water injection has been tested in the target area,but the effect varies greatly in each area,and the adaptability of periodic water injection is not clear.In view of the above problems,this thesis adopts the method of combining laboratory experiments and theoretical research to study the adaptability of the periodic water injection mode in the target area,and uses the means of numerical simulation to optimize the periodic water injection parameters.First,by analyzing the geological characteristics and the contradiction of water breakthrough in the stable water injection period,each area of the XC ultra-low permeability reservoir is divided into four types of water breakthrough modes,and the development contradiction in the stable water injection period is clarified.Secondly,an effect evaluation method is proposed,and corresponding modules are compiled to evaluate the effect of the current periodic water flooding field test.Combined with the water breakthrough model and the periodic water flooding effect,the main controlling factors of the periodic water flooding are clarified: including the development degree of the interlayer,the interlayer permeability difference and the crack development.Then,based on the three main control factors,the periodic water injection adaptability experiments of different types of fractured cores,different permeability gradients and interlayer development were designed,and the periodic water injection mode under the condition of large-scale fractures,interlayer permeability gradient and interlayer development was clarified.adaptability.Finally,based on the adaptability research results,typical well groups with different water breakthrough modes are selected,and a numerical simulation model is established.The response surface method is used to optimize the periodic water injection plan,and the periodic water injection parameters such as water injection timing,injection volume and injection stop period are optimized to form a A set of periodic waterflooding field experiments with strong adaptability to XC ultra-low permeability reservoirs.Through the research of this paper,it is helpful to clarify the adaptability of periodic water injection in different areas of XC ultra-low permeability reservoir,evaluate the effect of periodic water injection,and provide certain guidance for the subsequent periodic water injection adjustment in the study area.