Damage Research Of Cement Loop On Repairing The Destroyed Casing Well

In this paper, mechanical principle of roll-performing and impact-performing is analyzed in detail in order to solve the problem that cement loop is damaged again. Mechanical model of roll-performing is built based on static state. According to strain coordination condition, the force and deformation state formulas of casing, cement loop and stratum are derived. Mechanical model of impact-performing is built, attenuation coefficient of stress wave is derived spreading in casing, cement loop and stratum, and stress distributing is described accurately in cement loop based on the theory of impact dynamics and stress wave spreading theory. The problem that the cement loop is damaged by buckling drill pipe in impact-performing system is studied based on big deformation theory. Depending on the mechanical model of cantilever beam, the balance displacement shape of drill pipe is calculated, the wave number of buckling drill pipe and lateral force is also calculated. The cement loop is researched in detail with damage mechanics and the damage criterion of the cement loop is built based on the damage mechanical model of cement material.A set of calculative software is programmed in Visual Basic 6.0 language according to roll-performing and impact-performing analysis. The software runs well. The analytic result mainly accords with the real result. So it can conclude that the theory analysis, mechanical model and calculative way are reasonable. The comparison of the cement loop damage between roll-performing and impact-performing shows that the cement loop damage caused by roll-performing is smaller than impact-performing, but impact-performing apply widely. So the operational technology of impact-performing is researched emphatically and improved in the hoisting high and impact number. Not only can it raise the repairing quality, but also establish the base to reduce damage of the cement loop.