Study On The Seepage Flow And Rock Damage Mechanism Of The Sand Production In Sandstone Reservoir

Sandstone reservoirs are widely distributed in China's oil reservoirs,and sand production has always been a technical problem to be solved urgently in the process of reservoir mining.Practice shows that in recent years the reservoir,sand can dredge formation,optimize pore structure,improve the formation permeability,is conducive to the production of oil and gas;a large amount of sand will lead to the accumulation of sand strata,caused by plugging,wellbore sand plug production and equipment wear.Therefore,the study of sand production mechanism of sandstone reservoir and reasonable sand control can provide technical support for increasing oil and gas production and saving the cost of mining.This paper will based on meso damage theory,using the method of theoretical research and numerical simulation combined with the dynamic process in the process of sandstone reservoir exploitation in meso damage until the sand skeleton as the main research content,with the help of CT scanning technology and digital image processing technology,the dynamic evolution process of sandstone under the action of mining power is studied from microscopic perspective.The main contents are as follows:(1)Select the typical core and use CT scanning technology to obtain the CT image of the core,Binaryzation of core gap structure image based on the MATLAB image processing toolbox,obtain the core meso-structure;and the use of statistical method combining with the relevant statistical parameters distribution of sandstone micro node obtained from CT experiment,a statistical model of sandstone is established.(2)Using CT processing to obtain the core microscopic parameters(pore radius,pore distance,pore equivalent angle),the damage variable,the establishment of sandstone meso damage constitutive model and damage evolution equation are derived,based on the two development of the UMAT subroutine interface provided by the finite element software ABAQUS,the constitutive model of the sandstone meso damage is realized.(3)Based on the statistical damage constitutive model of sandstone,the feasibility of the damage constitutive model is verified by numerical simulation analysis of uniaxial compression,uniaxial tension and pure shear test of the unit,and the accuracy of the developed subroutine is verified.(4)Based on the developed subroutine,the sand production of sandstone is simulated on the finite element software ABAQUS,The study of sandstone under the action of load,the meso-structure of sand fracturing,expand to destruction,until the sand from the parent peeling resulting in sand micro dynamic evolution process,discusses the general rules of sandstone the analysis of sand,sand production and the meso damage mechanism.