Study On Mechanical Properties And Compressibility Of Tight Sandstone Reservoirs

The evaluation of reservoir rock mechanical properties is necessary for unconventional reservoir engineering dessert prediction,fracturing horizon selection and fracturing schemes.Experiment evaluation of compressibility can accurately test core mechanical parameter data,but due to the limitation of coring difficulty and number of cores,continuous formation profile data cannot be obtained.Logging data can be used to analyze data of different depths in the whole well interval.However,due to large indirect calculation errors,the accuracy of evaluation results is low.Therefore,we need to combine the advantages and disadvantages of experiment and logging evaluation to analyze the mechanical properties of tight sandstone reservoirs,to provide guidance for the evaluation of compressibility.In this paper,we choose tight sandstone as research object,carry out ultrasonic testing,uniaxial compression testing and stress sensitivity testing under cyclic loading in the laboratory,analysis the wave velocity,anisotropy and elastic characteristics of tight sandstone.Point out that in the process of stress loading,both the crack porosity and aspect ratio of cracks tend to decrease first and then increase with the stress,and crack density decreases with the stress.Get the fitting relationship between dynamic and static elastic parameters and between crack density and stress sensitivity coefficient.Set a method which can quantitative evaluation anisotropy influencing factors of rock with wave velocity stress sensitivity.The method can determine the proportion of the influence of crack and matrix on rock anisotropy,and quantitatively distinguish the influence of stress anisotropy and material anisotropy on rock elastic properties.Considering the influence of microcrack on the mechanical properties and compressibility of tight sandstone,combined with experiment experiments and logging data.Not only analyze the traditional compressibility evaluation parameters,but also analyze the stress sensitivity and the stress difference of the interlaye.Choose Linxing block as object.It is pointed out that the stress difference between the reservoir and the interlayer of some layers is the main factor that restricts the effect of reservoir reconstruction.It has reference value for the optimal design and construction of fracturing in tight sandstone reservoir.