Research On Mechanical Characteristics Of Unconventional Reservoirs In The Middle Eastern Qinshui Basin

The C area is located in the middle and eastern parts of Qinshui Basin,where coalbed methane and shale gas is rich.The development of coalbed methane and shale gas needs reservoir fracturing reformed,and mechanical parameters of reservoir and crustal stress characteristics are important to design the fracturing project.Therefore,mechanical characteristics of main coal bed and shale reservoir in the study area are reaearched in the paper to provide data support for reasonable development program of coalbed methane and shale gas.Logging data preprocessing,acoustic time difference logging curve reconstruction,logging response characteristic Statistic,stratigraphic division and correlation,shear wave time difference prediction model building,lithomechanic characteristics of reservoir and crustal stress prediction and research on reservoir mechanical parameters and plane distribution characteristics of crustal stress are carried out based on Logging,coring and testing data of the study area and a lot of references.Research shows that density value and acoustic travel time value are closer to the real value through environmental correction.Acoustic time difference logging curve needs to be standardized in consideration of large correcting value,while density and natural gamma logging curve consistency are quite well.Cross-plot is good to recognize coal bed,while to shale,natural gamma-density,natural gamma-density-acoustic time difference and natural gamma-resistivity cross-plot are better,but density-acoustic time difference,density-resistivity and acoustic time difference-resistivity are not good.?lgR recognition method does well in identifying coal bed and shale.Stratum in C area is thick in north but thin in south with little difference as a whole.3~#and 15~#production coal beds thickness change little horizontally as well as stratigraphic fluctuation.Shale reservoir thickness is stable integrally.The multivariate regressive method predict shear wave time difference more accurately.The Young modulus of coal bed is considerably lower than its roof and floor(Sandstone,mudstone)with gentle horizontal variation.The average Young modulus of shale is 35.92Gpa,and its Poisson's ratio is higher as well as the compression strength,what's more,there is a good linear relationship between dynamic and static strength parameters.Mechanical parameters of reservoir in Area C show a decreasing trend in SE-NW direction as a whole,while vertical stress,the maximum and the minimum horizontal main stress show a Increasing trend in SE-NW direction with abnormal stress in some areas.