涪陵焦石坝区块页岩动静态弹性模量转换关系研究

油气开采过程中,常通过测井资料和室内试验2种方式获得岩石的力学参数,通过测井资料获得的动态力学参数与通过室内试验获得的静态力学参数相比,在资料的数量、实时性以及获取成本等方面都具有明显优势,而现有力学本构关系是基于静态力学参数建立的,因此有必要建立动静态力学参数的转换关系。鉴于此,选取层理发育完好的涪陵地区焦石坝区块下志留统龙马溪组页岩,逐一分析不同层理角度、孔隙度和声波频率对页岩弹性模量的影响,结果表明,层理角度对页岩弹性模量影响规律最强。根据试验结果,利用相关性分析法建立了层理角度与动静态弹性模量的转换关系模型,并对相同区块的页岩进行了模型验证,发现该模型预测值的平均误差小于6%,具有误差小且计算简单的特点。该研究结果可为获得层理性页岩的动静态弹性模量转换关系提供一种快速有效的方法。 

Dynamic and Static Elastic Modulus Conversion for Shale in the Jiaoshiba Block,Fuling Area

Mechanical parameters of rocks can be obtained in two ways: well logging and laboratory experiments. The determination of dynamic mechanical parameters from well logging is much superior to those obtained through lab tests in terms of the data quantity, real-time performance and acquisition costs. Existing mechanical constitutive relationships are based on static parameters, so it is necessary to define the conversion between dynamic parameters and static ones. For this purpose, shale with intact bedding structures in the Lower Silurian Longmaxi Formation of Jiaoshiba Block, Fuling Area, was used to determine the impact of bedding angles, porosities and acoustic frequencies on the elastic modulus of shale. Research results showed that the bedding angles had the highest impact on the elastic modulus of shale. Accordingly, the conversion model between dynamic and static elastic modulus was established by using the correlation analysis method. Samples of shale taken from the same block were used to verify the results of the model. It was determined that the model had an average prediction error of less than 6%. The research results may provide an effective way to calculate dynamic and static elastic moduli for interbedded shales.