Reaesrch On Casing Damage Affected By Reservoir Development Of Yushulin Oilfield

In the oil field production process, changes in reservoir pore pressure will cause deformation of formation, and the deformation will make casing generate additional force. If the deformation of formation is bigger, the casing may generate a higher additional force and cause casing damage happened. Facts have proved that the fluid-solid coupling effect is an important factor of casing damage happened. So, this research will quantitatively analyse the mechanism of fluid-solid coupling effect and other factors causing casing damage happened deeply, considering the low permeability, permeability anisotropy and reservoir heterogeneity characteristics of Daqing Oilfield Yushulin region. This effort will provide strong technical support for extending the Yushulin oilfield casing serviceable life and ensuring the oilfield efficient production.Firstly, with respect to the fluid-solid coupling filtration theory, the governing equations of fluid-solid coupling model in permeability anisotropy and low ermeability reservoir were derived based on generalized Darcy's law and the assumption of small deformation of solid. On the base of the governing equations the fluid-solid coupling finite element programs for permeability anisotropy and low ermeability reservoir were developed with FEPG., and the traits and reliability of the programs were certificated.Secondly, With respect to the Elasticity theory, the Analytical Solution of casing Stress status in effect of pore pressure, fluid column pressure, ground stress and gravity was derived, also the programs of Elasticity theory was developed. Considering the effect of fluid-solid coupling and the factors mentioned above impact on casing damage, the software of casing damage prediction suitable for Daqing Oilfield Yushulin region was developed.and the interface map, Organization chart and Calculation Flow chart was given.Thirdly, with the finite element program, this research analyzed permeability, production pessure, interwell effects and faults on the impact of casing damage because of the fluid-solid coupling effects. Study shows that Fluid-solid coupling effects are an important factor of casing damage, the quantity of permeability and permeability anisotropy have significant impact on casing damage, and under fluid-solid coupling effets, fault activity is an important factor of casing damage.Finally, finite element computational geometry model automatically generated procedures under complicated geological conditions are developed in this paper. According to geological data of Daqing Oilfield Yushulin region, it set up the geometric model of three blocks. And it shows the traits of thin oil layer, bad vertical distribution of the continuity, serious non-homogeneous plane of Yushulin region. According to production records of the history to oil and water wells, it improves simulated function of the finite element calculation to 4-dimensional and 3 field. With the casing damage software, casing damage of three blocks in Yushulin oilfield is calculated. At the same time, the damage mechanism of the three blocks of the same sets of points and different points are analyzed.And the correctness of casing damage software is successfully verified in accordance with the original sets of three blocks.Through this study, the alteration history of casing stress level effect by fluid-solid coupling and other factors of daqing yushulin oilfield was defined, this effort will provide strong technical support for extending the Daqing Oilfield Yushulin region casing serviceable life and ensuring the oilfield efficient production.