Aspect ratio of spalls of granite in flame-jet spallation and its effect on the modeling prediction of spallation properties
Aspect ratio of spalls of granite in flame-jet spallation and its effect on the modeling prediction of spallation properties
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DOI：
10.1016/j.petrol.2018.08.050
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发表时间：
2018-12
影响因子：
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通讯作者：
Xiaodong Hu;Xianzhi Song;Yu Liu;Gensheng Li;Zhonghou Shen;Z. Lyu
中科院分区：
文献类型：
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作者：
Xiaodong Hu;Xianzhi Song;Yu Liu;Gensheng Li;Zhonghou Shen;Z. Lyu
热喷钻井是一种有效的硬岩层钻井技术。基于威布尔统计失效理论的模型在热仿真中得到了广泛的应用。长径比（直径/厚度），威布尔模型中的一个参数，被假定为一个常数，在以前的模拟火焰喷射spandum。我们在花岗岩中进行了火焰喷射实验，并收集了280个碎片来计算长宽比。结果表明，纵横比是尺寸依赖性。提出了一种新的三峰分布的纵横比，将威布尔模型，以准确地预测穿透率。比较结果表明，尺寸相关的纵横比对渗透率有显着影响。同时，建议采用较小的长宽比（6.91）对Weibull模型中的表面温度进行预测，使预测结果与已发表的数据有较好的吻合。此外，考虑到纵横比和6.91（无量纲）和70 Mpa的岩石固有强度，建议均匀性系数在10和17（无量纲）之间。该研究为采用威布尔模型模拟花岗岩中火焰喷射雾化特性提供了准确的长宽比。
Thermal spallation is an effective drilling technique for hard rock formations. Models based on Weibull statistical failure theory are widely used in the simulation in thermal spallation. The aspect ratio (diameter/thickness), a parameter in Weibull models, is assumed as a constant in the previous simulations of flame-jet spallation. We conducted the flame-jet experiment in granite and collected 280 spalls to calculate the aspect ratio. Results show that the aspect ratio is size-dependent. A new trimodal distribution of aspect ratio is proposed to incorporate in Weibull models to accurately predict the rate of penetration. The comparison results show that the size-dependent aspect ratio has a significant effect on the rate of penetration. Meanwhile, a smaller aspect ratio (6.91) is recommended for the prediction of the surface temperature in the Weibull model, by which the predicted result can get a better match with the published data. Additionally, given the aspect ratio and rock intrinsic strength of 6.91 (dimensionless) and 70 Mpa, a homogeneity factor is recommended between 10 and 17 (dimensionless). This study can provide an accurate aspect ratio for simulating properties of flame-jet spallation in granite using Weibull models.