地层流变对套管载荷的影响研究

ANALYSIS OF EFFECTS OF SURROUNDING ROCK RHEOLOGICAL BEHAVIOR ON CASING LOAD

针对由于地层具有流变特性对套管载荷的影响以及由于泥岩浸水等因素造成的地层流变特性改变而对套损产生影响等问题,根据开尔文模型推导了流变地层中套管载荷和地层粘度的关系,从而反映了套管载荷随时间的变化,在此基础上分析了流变地层岩石力学参数对套管载荷的影响。分析认为地层的粘性不同,其流变程度不同,导致套管达到最大载荷的时间不同。由于泥岩浸水导致岩石弹性模量降低,在相同地应力场作用下会明显加大最终作用在套管上的载荷,从而大大增加了套损的危险性。研究结果揭示了围岩流变导致套管损坏的机理。

Rheological behavior of formation can influence the casing load,and the change of formation rheological behavior caused by some factors such as mudstone immersion will affect casing damage.With the consideration of the problems mentioned,some research work has been done.The relationship between the casing load and formation viscosity of the flowage formation is derived according to Kelvin model,and from this relationship the change of casing load with time can be known.Based on the research,the effect of rock mechanics parameters on casing load in flowage formation is analyzed.According to the analysis it is determined that for the formations with different viscosities the different rheological degree will result in reaching the maximum load in different times.The mudstone immersion results in the decrease of rock elasticity modulus,and under the same crustal stress field the load to the casing will increase obviously,and then the possibility of casing damage will be increased greatly.The study results of this paper indicate the casing damage mechanism caused by the rheological behavior of surrounding rocks.