Cracking mechanism of rock by pressure pulses
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摘要: 基于爆燃压裂造缝原理,研制了可以模拟爆燃加载环境的岩石冲击开裂实验装置,为进行动载下的岩石开裂机理研究提供了实验手段。根据动量和能量守衡原理等,建立了冲击峰值压力和加压速率计算模型,模型计算结果与16次钢质岩心实验结果间平均相对误差分别为2.56%和4.04%,具有较高的精度。39次岩石冲击开裂实验结果分析表明,冲击能量和平均加压速率是影响岩石开裂以及开裂能否形成多条裂缝的主要因素;多条开裂裂缝的形成更大程度上取决于平均加压速率,且存在明显的临界平均加压速率;基于实验结果的灰色关联分析和多元二次多项式回归,建立的裂缝条数计算相关公式具有较高的精度,为油气田开发中爆燃压裂技术的机理研究和施工参数设计与控制提供重要的依据。Abstract: Based on the exploding fracturing principle, an experimental device on rock fracturing was developed to study the rock cracking mechanism by pressure pulses. According to the laws of energy and momentum conservation, the calculation models of the peak pressure and the pressurization rate were presented, which were revised by the 16 times steel core experiments and the models precision were proved for the average relative deviations between the experimental results and the calculated results were 2.56% and 4.04% separately. The calculation models can guide the experiment. Thirty nine times experiments on rock cracking show that shock energy and pressurization rates are the main factors influencing the status of rock cracking and the foremost factor affecting the fracture number is the pressurization rate, which there is an apparent critical pressurization rate. The precise correlation of the fracture number was regressively analyzed by using the gray relational theory and the multivariate second-degree polynomial method on the experiment results. The study is important for the design and application of the explosive fracturing technology in the oil and gas field.
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Key words:
- solid mechanics /
- cracking mechanism /
- pressure pulses /
- rock /
- calculation model
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