The Calculation Of Casing Failures Numerical Simulation In Daqing Oilfield

Currently, during the oilfield development ,the operational environments of oil-water well deteriorate increasingly with the longer production hours and continuous actualization of development projects, especially the actualizing of water flooding and polymer flooding .Casing failures are already international general problems and casing failures speed is increasing with years.The total caing failure ratio waves from several percent to 20-30 percent. The casing failure ratio in cer local area is as high as 70-80 percent.The casing failure current isn't kept in limit wholly in Daqing,in China,even in the world. The casing failure mechanism study, especially the quantitative study of casing failure mechanism, isn't systemic. The casing failure wells are increasing with years and its number exceed 500.These wells badly affect oilfield production and bring great economic losses .With the enlarging of oilfied scale and the increase of total casing failure wells,oilfield is under greater and greater affect from casing failure .So the quantitative study and application of casing failure mechanism and protective study are problem that is coming to a head. Based on the above reasons, the authors of this article started this study.The subjects involved in this paper are rock mechanics, fluid mechanics in porous medium, theory of elasticity and plasticity ,reservoir physics, non linear finite element analysis, and so on .Constitutive relation of rock is also to be studied. The numerical simulation study of casing failure mechanism has commanding theory sense .This paper builds the mathematical model by studying effect to casing failure brought by liquid-solid coupling, injection-production, working, geologic condition. Reducing the virtual seeking for answer and realizing the breakthrough of this theoretic equation from theoretical investigation to technical application by studying the saturation two-phase fluid flow ,pore medium deformation coupling,also discussing the estimates to some related parameters. This paper carries a history matching of injection-production by studying the leading area of the middle block of North 1 area locating in oil product No.1 of Daqing oilfield .Coincidence rate of wells in calculation to wells in actual is 83.3%. A result educed by computing is the casing failure will appear if casing Mises stress increases 17-35 Mpa or casing Mises stress reach 300 Mpa . Raising or reducing pressure of water-oil wells, the stress acting on casing will change correspondingly .The Mises stress acting on water-oil wells casing concern bottom hole pressure very nearly.Grid method in this paper is continuing to improve in studying. Applying of this advanced technology will make mass analyzing-computing possible.By the study, one may see that it realize the breakthrough of this study from theoretical investigation to technical application. Which is one of its advantage, but such technique is semi-quantity prediction technique , which is one of its disadvantage. In practical use , it may have better effect if one combines such technique with other reservoir prediction techniques.