单相水流诱发裂缝内煤粉启动机理与防控对策

发布时间：2018-07-11 18:14

本文选题：煤层气井 + 煤粉　；参考：《石油学报》2017年08期

【摘要】：煤层气井排水阶段是产煤粉的关键时期,煤粉运移不但会降低煤层渗透率,而且还会堵塞井筒和损坏设备。基于水动力学原理、扩展DLVO理论和JKR接触理论,开展了单相水流阶段裂缝面黏附煤粉的受力分析,建立了以"压力梯度"为判决条件的煤粉启动力学模型,分析了颗粒尺寸、颗粒类型、裂缝缝宽和离子强度对煤粉启动的影响,并围绕"适度出煤粉"和"阻止煤粉运移"两大思路提出了相应的防控对策。结果表明:煤粉启动压力梯度随着粒径的增加,先减小、后增大;裂缝缝宽越大,煤粉启动压力梯度越小;在不利化学黏附条件下有机质颗粒的启动压力梯度小于黏土矿物微粒,但在有利条件下却大于黏土矿物微粒;有利条件下的煤粉启动压力梯度远大于不利条件下的启动压力梯度。基于"适度出煤粉理论"设计煤层合理压力梯度区间时,应以优先改善最大缝宽裂缝的渗透性为原则,向煤层中注入煤粉稳定剂可提高煤粉-裂缝面间的黏附力,从而有效阻止煤粉运移。
[Abstract]:The drainage phase of coal seam gas well is the key period of pulverized coal production. The movement of coal powder will not only reduce the permeability of coal seam, but also block the shaft and damage equipment. Based on the principle of hydrodynamics, the DLVO theory and the JKR contact theory are extended to carry out the stress analysis of the coal powder in the phase of the fracture surface in the phase flow stage, and the "pressure gradient" is established as the judgment bar. The effect of particle size, particle type, crack width and ionic strength on pulverized coal starting is analyzed, and the corresponding prevention and control countermeasures are put forward around the two ideas of "moderate pulverized coal" and "stop pulverized coal migration". The results show that the coal powder starting pressure gradient decreases first and then increases with the increase of particle size; The higher the width is, the smaller the pulverized coal starting pressure gradient is, the starting pressure gradient of the organic matter under the unfavorable chemical adhesion is smaller than the clay mineral particles, but in the favorable conditions it is larger than the clay mineral particles; the pulverized coal starting pressure gradient under favorable conditions is far greater than the starting pressure gradient under the unfavorable conditions. When designing the reasonable pressure gradient interval of coal seam, the principle of improving the permeability of the maximum seam wide crack should be given priority, and the pulverized coal stabilizer can be injected into the coal seam to improve the adhesion force between the coal and the crack surface, thus effectively preventing the movement of the coal powder.
【作者单位】：西南石油大学油气藏地质及开发工程国家重点实验室;
【基金】：国家自然科学基金项目(No.51674209);国家自然科学基金青年科学基金项目(No.51604236) 非常规油气层保护四川省青年科技创新研究团队项目(2016TD016)资助
【分类号】：TE37

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