| Has the problem in the well cementation system which the well cementation expires to receive the scientific research attention gradually,the well cementation integrity can enhance the oil well generally the production efficiency and the use efficiency.Usually the limestone is most important simultaneously also is easiest to appear the destruction in the well cementation the spot(well cementation to expire generally has plastic deformation or yield failure for cement sheath),the limestone destruction generally destroys much the mine shaft complex stress function and the corrosion;In domestic and foreign already had the massive scholars’ to do the research which the limestone corrosion preventing destroyed,but in the cement sheath,the stratum and the sheathing material parameter influence well cementation system quality aspect studied few,still was at the preliminary exploration stage.This article reduces the experiment through the three axle to imitate the mine shaft mechanics environment,thus the research well cementation limestone mechanics behavior,in encircles differently presses under the environment the limestone to display the different peak value intensity and the remaining intensity,the recombination statistics damage model study limestone plastic conditioning.Finally through the large-scale commercial software comsol establishment well cementation system model(drive pipe-cement sheath-stratum model),through the drive pipe,the cement sheath and the stratum material parameter change carries on the sensitive analysis.(1)through does encircles differently depress the limestone the three axle to compress obtains compares has encircles presses under the function the limestone axial stress to have the obvious enhancement.When has encircles presses the function,in front of peak value plastic stage obvious extension,and the limestone plasticity starts to appear the strengthening,in which most prominent is the limestone deviator stress and the axial strain all has the remarkable increase,and is accompanied by the limestone remaining intensity.In has encircles presses under the function,the limestone stress-strain curve bending strain has obviously reduces,and also changes long the curve slope in the rise stage to increase(elasticity coefficient fill-out),encircles the area regarding the triaxial test curve and the axial strain to have Cheng Bei the increase,in this process consumes the energy also can increase.(2)has analyzed the limestone crack as well as from the different angle definition limestone damage variable from the viewing carefully angle,establishes the limestone the statistical damage model.(3)through the comsol commercial software establishment drive pipe-cement sheath-stratum model,changes the material parameter under certain intrinsic pressure to the cement sheath plastic deformation influence,passes through the different parameter change discussion cement sheath plastic deformation change,screens to the cement sheath plastic deformation influence big parameter.(4)this article uses the analytic hierarchy process to pass the cement sheath elasticity coefficient,the cement sheath poisson’s ratio,the cement sheath cohesive force,the cement sheath angle of internal friction and the cement sheath density;Drive pipe elasticity coefficient,drive pipe poisson’s ratio and drive pipe density;The stratum elasticity coefficient,the stratum poisson’s ratio,the stratum cohesive force,the stratum angle of internal friction and the stratum density take the limestone quality quality synthetic evaluation target;Screens the cement sheath elasticity coefficient,the cement sheath poisson’s ratio,the stratum elasticity coefficient and the cement sheath cohesive force parameter through the analytic hierarchy process the cement sheath plastic deformation influence is biggest to the well cementation system in;And is consistent with the value simulation analysis result. |
