基于声发射行为页岩压裂裂缝破裂方式演化研究

发布时间：2018-05-18 09:00

本文选题：页岩压裂 + 声发射　；参考：《东北石油大学》2017年博士论文

【摘要】：本文以不同脆性页岩压裂裂缝扩展产生的声发射信号为切入点,通过对声发射信号进行小波分析与判别刻画出不同脆性页岩压裂裂缝相互作用发生张性破裂、剪切破裂与混合破裂的内在规律。课题的具体研究工作与研究成果包括如下几个方面:首先,研究了页岩储层多尺度裂缝分布的多重分形描述方法,建立了考虑多尺度天然裂缝分布的页岩岩体脆性指数表征方法。结合小波分析方法开展岩体破裂声发射源的三维定位研究。将新的脆性指数引入到声发射传播波动方程中,建立了裂缝扩展声发射传播波动方程与矩张量判别方法。其次,开展了岩体破裂与声发射信号联测试验,根据不同脆性岩体破裂的声发射传播特性,结合矩张量判别方法,研究了不同脆性页岩岩体的破裂规律,研究结果表明:岩体脆性强度较小时,声发射响应时间分散,岩体呈延变式破裂,且多以单一破裂面为主,声发射现象集中在规则破裂面周围。当岩体脆性强度较大时,声发射响应时间集中,岩体呈突变式破裂,岩体破裂呈现多样化,出现多个破裂面,声发射在岩体内多区域分布,破裂既有阻尼特征的塑性破裂,又有多模态的脆性破裂。再次,基于声发射计数定义压裂岩体破裂与裂缝演化的损伤变量,基于声发射响应特征建立了压裂岩体损伤破裂的折迭突变模型。根据能量释放与声发射波动方程,研究了岩体压裂裂缝演化与声发射行为的内在关系。最后,开展了页岩水力压裂与声发射联测试验,基于声发射矩张量方法研究了不同脆性页岩天然裂缝与水力裂缝相互作用的情况。研究结果表明,裂缝缝网是在天然裂缝与水力裂缝相互作用下,裂缝发生张性破裂、剪切破裂与混合破裂共存的作用结果。天然裂缝的存在不仅扰动了水力裂缝由张性演化扩展模式向剪切、混合演化扩展模式转变,同时也诱导了天然裂缝自身端部的剪切裂缝演化扩展模式的产生,增加了裂缝演化扩展破裂面的复杂程度与缝网复杂性计算的难度。且页岩岩体的脆性特征对裂缝间的作用行为具有控制作用。从声发射的角度,揭示了岩体脆性越强,越容易形成缝网的一般规律。总之,从岩体破裂的声发射特征出发,研究不同脆性页岩压裂水力裂缝与天然裂缝相互作用时,裂缝破裂方式的一般规律。该课题的选题与研究内容为页岩压裂岩体损伤破裂行为与裂缝网络体系演化机制研究开辟了新的思路与研究方法,对清晰认识页岩压裂裂缝网络体系形成规律具有重要意义与学术价值,为后续基于声发射参数及波形特征的页岩压裂储层改造效果评价及压裂施工与参数优化研究奠定科学基础。
[Abstract]:In this paper, the acoustic emission signals produced by fracture propagation of different brittle shale fracturing are taken as the starting point. By wavelet analysis and discrimination of acoustic emission signals, the tensile fracture of fracturing fractures in different brittle shale fracturing is characterized by wavelet analysis and discrimination. The inherent law of shear fracture and mixed fracture. The specific research work and research results include the following aspects: firstly, the multifractal description method of multiscale fracture distribution in shale reservoir is studied. A method for characterization of brittleness index of shale rock mass considering multi-scale distribution of natural fractures is established. Three-dimensional localization of acoustic emission source of rock mass fracture is studied with wavelet analysis method. The new brittleness exponent is introduced into the wave equation of acoustic emission propagation, and the wave equation of propagation of crack propagation and the method of moment Zhang Liang are established. Secondly, the combined test of rock mass fracture and acoustic emission signal is carried out. According to the characteristics of acoustic emission propagation of different brittle rock mass, combined with moment Zhang Liang discriminant method, the fracture law of different brittle shale rock mass is studied. The results show that the ductile strength of rock mass is small, the response time of acoustic emission is dispersed, the rock mass is rupture with a single fracture surface, and the phenomenon of acoustic emission is concentrated around the regular fracture surface. When the brittle strength of rock mass is high, the response time of acoustic emission is concentrated, the rock mass is ruptured suddenly, the rock mass fracture is diversified, there are many fracture surfaces, the acoustic emission is distributed in many areas of rock body, and the plastic fracture with damping characteristic is obtained. There are also multiple modes of brittle fracture. Thirdly, the damage variables of fracture and fracture evolution of fracturing rock mass are defined based on acoustic emission counting, and the fracture break model of fracturing rock mass is established based on acoustic emission response characteristics. Based on the wave equation of energy release and acoustic emission, the relationship between fracture evolution and acoustic emission behavior of rock mass fracturing is studied. Finally, the combined testing of hydraulic fracturing and acoustic emission of shale was carried out, and the interaction between natural fractures and hydraulic fractures of different brittle shale was studied based on the Zhang Liang method of acoustic emission moment. The results show that the fracture network is the result of tensile fracture and coexistence of shear fracture and mixed fracture under the interaction of natural fracture and hydraulic fracture. The existence of natural fractures not only disturbs the transformation of hydraulic fractures from tensional evolution to shear and mixed evolution, but also induces the generation of shear fracture evolution and propagation mode at the end of natural fractures. The complexity of fracture evolution extension surface and the calculation of fracture network complexity are increased. The brittleness of shale rock mass controls the interaction between fractures. From the angle of acoustic emission, it is revealed that the more brittle rock mass is, the easier it is to form a joint mesh. In a word, based on the acoustic emission characteristics of rock mass fracture, the general law of fracture mode under the interaction between hydraulic fracture and natural fracture of different brittle shale fracturing is studied. The topic and research contents of this topic have opened up new ideas and research methods for the study of damage and fracture behavior of shale fracturing rock mass and the evolution mechanism of fracture network system. It is of great significance and academic value to clearly understand the formation law of shale fracturing fracture network system. It lays a scientific foundation for the evaluation of shale fracturing reservoir reconstruction effect based on acoustic emission parameters and waveform characteristics and for the study of fracturing operation and parameter optimization.
【学位授予单位】：东北石油大学
【学位级别】：博士
【学位授予年份】：2017
【分类号】：TE377

【参考文献】