大庆油田注水开发套损机理及主控因素分析

Analysis of casing damage mechanism and main control factors in water-flooding development of Daqing Oilfield

大庆油田长期注水开发引起地层蠕动,进而造成套管损坏变形,制约了油田开采效率。为了探寻套管变形规律,揭示套管变形的主控因素,考虑流固耦合效应,建立了套管—水泥环—地层的三维模型,模拟了套管发生损坏的变形过程。结果表明:注水憋压引起的塑性变形或蠕变是油层套损的主要原因;套管屈服强度越小,岩石强度越高,地层渗透系数越高,套损越严重;注水压力越高,套管发生弹性变形速率越快,套管发生塑性变形越早,越容易发生套损。该研究为油田注水方案调整及套损预测提供了技术支撑。

Long-term water flooding development in Daqing Oilfield has caused formation creep,resulting in casing damage and deformation,which restricts the oilfield production efficiency.In order to find the law of casing deformation and reveal the main controlling factors of casing deformation,a three-dimensional model of casing-cement sheath-formation was established to simulate the deformation process of casing damage by considering the fluid-solid interaction effect.The results showed that the plastic deformation or creep caused by water injection pressure was the main cause of casing damage.The smaller the yield strength of casing,the higher the strength of rock,the higher the formation permeability coefficient,the more serious the casing damage happens.The higher the water injection pressure,the faster the elastic deformation rate of casing,and the earlier the plastic deformation of the casing occur,the more likely it is to cause casing damage.The study has provided technical support for adjustment of water injection scheme and prediction of casing damage in oilfield.