地面井预抽瓦斯运移规律数值模拟研究

魏建平; 王晓川; 姚邦华; 王云刚; 蔡东林

地面井预抽瓦斯运移规律数值模拟研究

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出版历程
- 发布日期: 2016-10-19

Numerical Study on Gas Migration Laws for Gas Pre-drainage of Surface Well

摘要

摘要: 基于气固耦合理论，建立了地面井预抽瓦斯的气固耦合力学模型和数值计算模型，并分析了地应力、储层压力等因素对地面井预抽瓦斯效果的影响。计算结果表明：地应力与煤层产气率之间呈现非线性负相关关系。抽采前期瓦斯的产出速率随地应力的增大而显著变小，随着抽采的进行，地应力对产出速率控制性逐渐减弱；储层压力与瓦斯产气率呈正相关关系。煤层瓦斯压力越大，初始瓦斯抽采效率越高，抽采产量越大，随着抽采时间的增加，煤层瓦斯压力下降，瓦斯抽采效率迅速降低；瓦斯产出速率由煤体渗透率和储层瓦斯压力梯度两者共同决定，抽采初期前者对瓦斯产出速率的控制性占主导地位，随着抽采的进行前者对其控制性要逐渐小于后者。
- 地面钻井 /
- 预抽瓦斯 /
- 气固耦合 /
- 运移规律 /
- 数值模拟
Abstract: Based on gas-solid coupling theory, we established gas-solid coupling seepage mechanics model and numerical model for surface well pre-drainage gas, and analyzed the effect of in-situ stress and gas pressure on surface well gas drainage. The calculation results show that in-situ stress presents nonlinear negative relationship with gas production rate; output rate of gas extraction from the early stage becomes smaller with the increasing of stress significantly, and the control of in-situ stress on gas output rate is gradually weakened with the advancing of extracting; reservoir pressure is positively related to gas output rate, and the larger of coal seam gas pressure, the greater of the initial gas extraction efficiency, the higher of extraction yield, and the gas pressure will decrease with the increase of the drainage time, and the gas drainage rate decreases rapidly; the gas production rate is controlled by coal seam permeability and coal reservoir gas pressure gradient, and the former has dominant control on gas production rate at early extraction stage, and the controlling of former is less than that of latter with the advancing of extracting.
- surface borehole /
- gas pre-drainage /
- gas-solid coupling /
- migration law /
- numerical simulation

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