Research On Carrying Capacity Of Water-injected Well Casing During Anti-cleanup

During anti-cleanup, especially pressure release, the Fluid Pressure Sag causes pressure difference between inwall and outwall and casing damage. In the process course of Anti-cleanup, casing damage has happened in Daqing, Shengli, Jilin oilfields etc. Varying rules of Anti-cleanup casing stress and Capacity of Anti-cleanup Casing is researched based on elastoplastic behavior of and fluid-structure interaction, which is of great significance and benefit for the Guidance of Anti-cleanup pressure control and the declines dimension.The process of Water-injected Well Anti-cleanup is a couple problems of material non-linear, geometry non-linear and structural dynamics. Through mechanical analysis, the 3-D Anti-cleanup mechanical model of Water-injected Well casing and strata is established, considering solid-fluid coupling , material non-linear , dynamic effect of fluid seepage. The stress equilibrium equations of casing and rock masses, and the fluid seepage equilibrium equations are established according to solid mechanics, seepage mechanics. Using finite element theory, Finite Element Scheme of fluid-solid coupling is obtained. Applied Abaqus software, established 3-D Water-injected Well Anti-cleanup Simulation model, according to Finite Element technology, carried out transient simulation analysis on Water-injected Well Anti-cleanup, simulated the stress and Capacity of Anti-cleanup Casing. Obtained Varying rules of casing stress and external pressure given by the strata throughout the Anti-cleanup and the influence rules of different strata characteristic and strata stress on Capacity of Anti-cleanup Casing.Through the inquisition and statistics data, obtained the relation between Water-injected well casing surplus thickness and age of work, and the morphological character of casing corrosion. Established 3-D Anti-cleanup Simulation model after casing Corroded, simulated residual bearing capacity of perforation casing with different morphological character, qualitatively analyzed some factors influence on residual bearing capacity of perforation casing, such as length, width, depth and distribution of corrosion pit and so on.With the great development of oilfield, the prediction software that suitable for using to 3-D the well cleanup pressure prediction is much needed and exigent. According to Finite Element technology, established 3-D Water-injected Well Anti-cleanup numerical Simulation method and techniques, provided more reliable and accurate predicted means for cleanup pressure design, made Anti-cleanup more efficient and scientific.