【作者】 马玉林；

【导师】 张永利；

【作者基本信息】 辽宁工程技术大学 ， 流体力学， 2008， 硕士

【摘要】 煤层气是煤炭伴生的洁净能源。勘探结果表明,中国拥有丰富的煤层气资源,但绝大部分储气煤层为低渗透煤层,煤层气开采量较小,无法形成大规模工业化开采。因此研究煤层气的解吸渗透特性,特别是低渗透煤层煤层气的具体开采方法,对于预防瓦斯事故,充分开发并合理利用煤层气资源具有重要的实际意义。目前,关于地应力及孔隙压力的改变对煤层气渗透率及产量的影响,国内外众多学者取得了大量理论及实验研究成果;在注气驱替煤层气以提升煤层气的渗透率和解吸量的方面,也得到了大批的成果。理论揭示,温度是改善煤层气渗透性能的一个关键因素。应用煤层气地质学、渗流力学和数学物理方法等理论,针对低渗透煤层的特点,根据煤层气的解吸、渗流变化规律及双重介质的三场耦合作用机理,建立了非等温条件下低渗透煤层气相流固耦合渗流的数学模型,详细推导了该数学模型的全隐式数值求解方法,并根据模型和工程实际数据进行了后续模拟分析。给出了开发注热开采煤层气藏储层数值模拟软件思路。根据实验获得的非等温条件下煤层气的解吸渗流规律,经数据拟合,分析得出:不同温度条件下,渗透率随孔隙压力的增加以指数形式递增;在相同围压、轴压和孔隙压力条件下,等温解吸时,煤样瓦斯渗流量随温度的增加而呈现指数递减规律;升温解吸时,解吸量比低温下的渗流量增加,孔隙压力越大,渗流量增加越明显。将实验数据与数值模拟的结果进行比较研究,认为在注热开采煤层气时,通过间歇式注热(蒸汽吞吐)使煤层温度梯度不断变化,煤层发生升温解吸,有利于煤层气的产出。对我国在低渗透煤层气藏开采中实现煤层气热采提出新的思路更多还原

【Abstract】 The coal-bed methane which is associated gas in coal is a clean energy source. The exploratory data show that there are rich coal-bed methane resources in China. But the production volume is so small that can not establish large-scale industrialized mining in most coal seams which are low permeability. The recovery and utilization of coal-bed methane prevent gas accidents and solve the problem of lack of energy. Therefore, it is highly significant that researching the characteristic of desorption and seepage and the method of exploitation of gas in the low permeability of coal. At present, many scholars at home and abroad have made a lot of theoretical and experimental research results on the effect of ground stress and pore pressure. It obtains a mess of productions that increase seepage rate and quantity of desorption by injecting other gas.It reveals that the temperature is one of the key factors which influence the permeability of gas. Aimed at the characteristic of the low permeability coal seam, and based on the regularity between desorption and the seepage and mechanics for coupled thermo-hydro-mechanical. A dual-porosity, two-phase mathematical model and numerical model for coal-bed methane in low permeability coal seam under unequal temperatures were given, according to the theories of coal-bed methane geology, mathematical physics and fluid mechanics in porous medium. Fully implicit numerical solution technique for dual-porosity, two-phase flow mathematical model was given in detail. And present the way to open out the simulation software of coal-bed methane. Fitted the dates by nonlinear curve fitting functions and analyzed their nonlinear least squares fitters. The nonlinear curve fitting functions are exponential functions. Some of the curves indicate that the seepage rate increases with the increasing of the pore pressure under different temperature. Some of the curves indicate the seepage quantities which are desorbed under the same temperature decrease with the increasing of the temperature under the same confining pressure, axial pressure and pore pressure. The seepage quantities are more than the low temperature’s when the temperature increases. Furthermore the increment of the seepage quantity is very obvious when the pore pressure increases. It avails the output of the coal-bed methane by the intermittent heating which gets the temperature gradient increasing. All above offer a new idea for the low-permeability coal-bed methane exploitation.更多还原