【作者】 肖晓春；

【导师】 潘一山；

【作者基本信息】 辽宁工程技术大学 ， 工程力学， 2009， 博士

【摘要】 本文利用煤层气运移理论、固体力学、孔隙介质理论、渗流力学、多相渗流、有限元数值计算等理论在总结前人己有的研究结果的基础上,进行了滑脱效应影响的低渗透储层气体运移规律的研究,完成了以下研究工作:1.根据低渗透储层的特点,进行了合理必要的力学假设,并在此基础上,建立了滑脱效应影响的低渗透储层煤层气运移的数学模型;建立了对煤层气采出有重要影响的气水两相渗流阶段的滑脱效应影响的低渗透储层气水耦合渗流模型;建立了滑脱效应影响的低渗储层单相气体渗流数学模型。2.利用滑脱效应影响的低渗透储层单相气体渗流数学模型,进行了解析分析,得到了有限长煤层滑脱效应影响的气体稳定流动的采场压力分布解析式;无限大煤层滑脱效应影响的气体不稳定流动的采场压力分布解析式;滑脱效应影响的低渗透无限储层气体单向不稳定流动采场产量预测公式;滑脱效应影响的球向不稳定流动的采场压力分布解析式以及低渗透无限储层气体球向不稳定流动采场产量预测公式。3.利用实验手段进行了考虑滑脱效应的低渗透储层煤层气运移实验和不同水饱和度下低渗透气藏气体滑脱效应实验,得到了新的滑脱效应数学拟合式并解释了式中各系数的物理意义;得到了滑脱因子和绝对渗透率之间的变化关系;解释了水饱和度、孔隙压力、环境压力对储层有效渗透率的动态影响;证明了低渗透环境下,滑脱效应存在的孔隙压具有高阈值性。4.开发了滑脱效应影响的气体单相非线性渗流以及滑脱效应影响的气水两相非线性渗流的有限元模拟程序。5.利用山西河东煤田柳林煤层气试验区现场试井资料和生产动态数据,分析了滑脱效应影响的不同开采条件下低渗透储层采场压力变化规律、采场气体流速变化规律、采场产量预测规律和采场气水两相饱和度的变化规律。数值模拟结果表明:滑脱效应对采场孔隙压力分布、气体流速变化、气体预测产量以及采场水饱和度变化有着重要的影响,主要体现在滑脱效应导致了开采井周围的储层压力下降加快,使得储层和开采井之间的压差增加,有利于煤层气的长效解吸;滑脱效应导致采场气体速率高于达西渗流的气体速率;滑脱效应导致气体产量预测更加接近煤层气历史拟合值;滑脱效应导致低渗透储层的气相饱和度很快达到饱和状态,水相饱和度也会随着开采的深入迅速下降并稳定,更加有利于煤层气的采出。本文的主要创新之处在于,根据低渗透储层的特点,建立了滑脱效应影响的低渗透储层煤层气运移数学模型;在此数学模型基础上建立了滑脱效应影响的气水两相渗流阶段的气水耦合数学模型;建立了滑脱效应影响的低渗透储层单相气体渗流数学模型;利用理论分析手段得到了不同流动特征下的采场孔隙压力分布解析式和产量预测公式;利用实验手段得到了滑脱效应影响的低渗透储层气体运移规律;解释了水饱和度、孔隙压力、环境压力对储层有效渗透率的动态影响;证明了低渗透环境下,滑脱效应存在的孔隙压具有高阈值性;开发了滑脱效应影响的气体单相非线性渗流以及滑脱效应影响的气水两相非线性渗流的有限元模拟程序,并利用数值模拟手段对滑脱效应影响的不同开采条件下的低渗透储层采场压力变化规律、采场气体流速变化规律、采场气体产量预测规律和采场气水两相饱和度的变化规律等方面问题进行了较为系统的研究。更多还原

【Abstract】 In summarize the predecessor some findings foundation, this thesis used theory of migration of coal-bed methane, solid mechanics, pore media theory, seepage mechanics, poly-phase seepage and finite element numerical simulation and so on, studied the rule of gas migration in hypotonic reservoir considering slippage effects, completed the following research work:1. According to the hypotonic reservoir characteristic, carried on the reasonable essential mechanics supposition, and based on this, established the mathematical model of coal-bed methane migration in hypotonic reservoir considering slippage effects, established the mathematical model considering coupling of gas and water and gas slippage effects that the material effect gas water two seepage stage in hypotonic reservoir, through simplification established the single-phase gas seepage mathematical model influence by slippage effects in hypotonic reservoir.2. Used the single-phase gas seepage mathematical model influence by slippage effects carried on the theory analysis, obtained the steady-flow pore pressure distribution analysis formula in the finite coal bed; gamma infinity hypotonic coal bed non-steady flow pore pressure distribution analysis formula influence by slippage effects; gas output prediction formula in gamma infinity hypotonic coal bed considered by gas slippage effects; spheric non-steady flow pore pressure distribution analysis formula with the slippage effects as well as the spheric non-steady flow gas output prediction formula in gamma infinity hypotonic reservoir.3. Used the experiment method carried on the experiment that gas migration in hypotonic reservoir considered gas slippage effects and the gas slippage effects experiment in hypotonic reservoir with different water degree of saturation, obtained the new gas slippage effects fitting formula and explained various coefficients physics significance in the formula; obtained the relation between the slippage factor and the absolute permeability; explained the water degree of saturation, the pore pressure and the environment pressure dynamic effected to the reservoir effective permeability; proved under the low permeability environment, the pore pressure of gas slippage effects existence had the high threshold value.4. Developed the single-phase gas nonlinear seepage and the gas-water two phase gas nonlinear seepage finite element simulators influence by gas slippage effects.5. Used the field engineering wells data and delivery dynamic data of liulin coal-bed methane experiment block in shanxi hedong coal field, analyzed the variation rule of pore pressure in hypotonic reservoir considering the slippage effects and different mining condition, the variation rule of gas current velocity, the prediction rule of gas output and the change rule of gas-water two degrees of saturation.The result of numerical simulation indicated: gas slippage effects had the significant contribution to distribution of pore pressure, changing of gas current velocity, gas prediction output and changing of gas-water degree of saturation, mainly manifested in the gas slippage effects caused the pore pressure drop accelerate around of the mining wells, increased differential pressure between the hypotonic reservoir and the mining wells that is advantageous the coal-bed methane persistent desorption; slippage effects caused the gas speed to be higher than daxi seepage gas speed; it caused the prediction gas output more closer to the coal-bed methane historical fitting value; it also caused the gas phase degree of saturation of low seepage reservoir to achieve the saturated condition very quickly, and the water phase degree of saturation also rapid drop and stable along with the mining thorough, it was more advantageous to coal-bed methane recovery.The main innovation of this thesis lied, according to the hypotonic reservoir characteristic, established the mathematical model of coal-bed methane migration in hypotonic reservoir considering slippage effects; and based on this, established the mathematical model considering coupling of gas and water and gas slippage effects that the material effect gas water two seepage stage in hypotonic reservoir, established the single-phase gas seepage mathematical model influence by slippage effects in hypotonic reservoir; used the theoretical analysis method obtained pore pressure distribution analysis formula and the gas output prediction formula under the different flowing characteristic; used the experiment method obtained the coal-bed methane migration rule in hypotonic reservoir considered the slippage effects; explained the water degree of saturation, the pore pressure, the environment pressure to the reservoir effective permeability dynamic effect; explained the water degree of saturation, the pore pressure and the environment pressure dynamic effected to the reservoir effective permeability; proved under the low permeability environment, the pore pressure of gas slippage effects existence had the high threshold value; developed the single-phase gas nonlinear seepage and the gas-water two phase gas nonlinear seepage finite element simulators influence by gas slippage effects and used the numerical simulation method to systematic research these questions such as the pore pressure changing rule in hypotonic reservoir different mining condition, the gas variation current velocity rule, the gas prediction output rule and the gas-water two degrees of saturation change rule considering the slippage effects and so on.更多还原