不同温压下页岩动态与静态弹性模量转换研究

岩石动态与静态弹性参数存在差异，在应用时需要进行转换。目前国内外学者对岩石动态与静态弹性模量转换实验多在常温与常压下进行测试，没有考虑温度和压力对测试结果的影响，导致转换结果不能充分反映储层力学性质。本次研究以四川盆地上奥陶统和下志留统的五峰组-龙马溪组黑色页岩为研究目标，开展不同温度与压力条件下岩石动态与静态弹性力学实验，并对测试结果进行分析。结果表明：①当温度与压力一定时，动态杨氏模量测试值比静态杨氏模量测试值大，并且二者有一定的线性相关性；②页岩动态与静态杨氏模量均与温度、压力有关，温度一定时，页岩动、静态杨氏模量均随着围压的增大而增大；压力一定时，页岩动态与静态杨氏模量均随着温度升高而降低，并对不同温度、压力条件下动、静态弹性力学参数变化规律进行了机理分析；③建立了不同温度、压力条件下页岩动态与静态弹性参数转换模型，该模型可以将任意温度、压力条件下测试的动态弹性参数转换为储层条件下岩石的静态弹性参数，并能取得较好效果。利用本模型可以为研究区页岩气开采及注水压裂施工方案提供可靠的静态弹性模量，研究具有一定的实际意义。

Experimental study on dynamic and static elastic modulus conversion for shale under different temperatures and pressures

There are differences between dynamic and static elastic parameters of shale.Thus when applied,they need to be converted.Most experiments carried out today by both domestic and foreign scholars in testing rock dynamic and static elastic modulus conversion are under normal temperature and pressure,without considering the influence of temperature and pressure on the results;consequently,the conversion results cannot fully display the mechanical properties of reservoirs.We studied the Wufeng-Longmaxi black shales of the Upper Ordovician and Lower Silurian in the Sichuan Basin,conducted mechanical experiments of rock dynamic and static elasticity under different temperatures and pressures,and analyzed the test results.The results show that:① when the temperature and pressure are constant,the dynamic Young's modulus test value is larger than that of the static Young's modulus test,and the two have a certain linear correlation.② The dynamic and static Young's moduli for shales are correlated with temperature and pressure.When the temperature keeps constant,the static and dynamic Young's moduli of shales increase with the increase of confining pressure.When the pressure is constant,the static and dynamic Young's moduli of shales decrease with the increasing temperature.Besides,the mechanism for the change of dynamic and static elastic mechanical parameters under different temperatures and pressures was analyzed.③ The conversion model for dynamic and static elastic parameters of shales under different temperatures and pressures was established.In applying the model,whatever the temperature and pressure,the dynamic elastic parameter obtained can be converted into the in-situ static one,and the results are reliable.This model can provide credible static moduli of elasticity for shale gas exploitation and hydraulic fracturing in the study area.All in all,the research is of certain practical significance.