【作者】 陈天宇；

【导师】 梁冰；

【作者基本信息】 辽宁工程技术大学 ， 工程力学， 2011， 硕士

【摘要】 我国低煤阶煤所包含的资源量约占全国煤层气资源量的47%,复杂地质条件下低煤阶煤层气藏的相关理论研究具有重要的理论意义和应用价值。论文基于煤层气地质学、渗流力学理论、有限差分理论,采用理论研究、数值模拟分析和现场实际生产数据资料相结合的方法,对复杂地质条件下煤层气藏群井排采的产能和压力扩展规律进行了研究,并对井网合理布局进行了研究,为煤层气地面开发提供了依据和指导。将煤储层抽象为双重介质,考虑了煤层气排采后压力变化引起的基质收缩对煤孔隙度和渗透率的影响,建立了基质、裂隙双重孔隙度,裂隙单一渗透率的煤层气藏渗流数学模型。采用隐式差分方法对所建立的煤层气渗流数学模型进行差分离散,推导和建立了可以迭代求解的线性煤层气藏渗流数值模型。以阜新刘家区块为背景,建立了考虑火成岩和断层构造的复杂煤层气藏地质模型。基于所建立的数学模型、数值模型和地质模型,对复杂地质条件刘家煤层气藏群井排采后的产能和压力扩展规律进行了仿真研究,通过区块煤层气井数值模拟结果和实际排采曲线的对比和分析,验证了论文所建立数学模型和地质模型的正确性。模拟得到地质构造影响煤层气排采后的储层压力扩展,封闭地质构造的存在改变了压力扩展的方式,压力扩展至封闭构造处时沿着封闭构造的走向扩展,在构造处的压力梯度较大。分析了端、面割理方向渗透率、地质模型和复杂地质条件对煤层气排采压力扩展和产能的影响:不考虑面、端割理渗透率的差异会使井的日产气量偏高,在相同条件下,排采后产生的有效井间干扰范围较大;采用理想地质模型计算得到的初始储量、日产量与实际会出现偏差;不考虑地质构造的普通地质模型煤层气井的产量与复杂地质条件储层有三种不同情况,且压力扩展和井间干扰的形成也有明显不同。对复杂地质因素影响下煤层气井的合理井间距进行了分析,地质构造影响煤层气井的布置,煤层气井与断层的距离越大,产能越高;煤层气井与侵入岩的距离确定为压裂影响半径时产能最高;在面割理方向和火成岩附近储层的煤层气井间距要适当加大,才能使端、面割理方向及多井排采时井间干扰的同时形成。基于上述煤层气井间距的分析,对刘家煤层气井网进行了优化,并且对刘家煤层气群井排采时的井网密度进行了研究,采用群井排采时,井数越多,井间干扰形成的时间越短,区块产能越高,煤层气的净收益越大,但是超过22口井时,井数再增加,区块产能提高不明显。更多还原

【Abstract】 Low coal rank coal contains about 47% CBM resources of the national CBM resources, related theory research of low coal rank CBM reservoirs under complex geological conditions has important theoretical and application value. Capacity and pressure distribution of complicatedly geologic CBM reservoir with multi-well exploitation were researched based on coal-bed gas geology, permeation fluid mechanics and finite difference theory by the method of theoretical research and numerical simulation, the reasonable well pattern arrangement was studied, that provides basis and guidance for CBM ground development.Coal was abstracted as double-porosity media. Dual porosity-single permeability CBM seepage mathematical model considering the matrix shrinkage duing to fluid pressure change were established.CBM seepage mathematical model were discreted by implicit difference method, CBM seepage numerical model were deduced which can be solved by iteration.Complicatedly geologic CBM reservoir model considering igneous rocks and faults was established on the background of Fuxin LiuJia CBM block. The off-take potential and pressure distribution of complicatedly geologic CBM reservoir were simulated and researched based on the mathematical model, numerical model and geologic model. The correctness of mathematical model and geologic model was proved through comparing numerical simulation results with actual production data. The simulation results shows that pressure distribution after extracting CBM are influenced by the geological factor. the way of pressure distribution is changed due to the close geologic structure, pressure spreading along the strike of intrusive dykes and faults, reservoir pressure gradient is greater in the place of igneous rocks and faults.The influence of face cleat permeability, butt cleat permeability, geologic model and complicatedly geologic structure on off-take potential and pressure distribution were analysed. Daily production is higher and the area of well interference is larger without considering the difference of face cleat and butt cleat. Initial reserves and daily production using geological model deviate from actual ideal geological model. There are three different patterns of CBM wells productivity in complicated geological reservoir comparing with ordinary reservoir based on the different distance from well to intrusive dykes and faults, pressure distribution and well interference of complicated geological reservoir are different from ordinary reservoir.Reasonable well spacing of complex geological CBM was analyzed. Well pattern arrangement is influenced by geological structure. The capacity of CBM well increases along with the increase of well distance with faults. When the distance of CBM wells and intrusive rocks equal to pressing crack radius, the capacity of CBM well is the largest. Wells spacing should increase appropriately in the direction of face cleat and in the place of intrusive rocks, that can make well interference form at the same time.Well patterns was optimized and well patterns density was analysed based on the analysis of the CBM well spacing. The more wells,the shorter time of well interference generation,and the larger capacity and net earnings.In LiuJia block,when wells exceed 22, the improvement of block capacity is not obvious.更多还原