摘要: 摘 要 煤系叠合型储层开发过程中储层组合影响了煤系气井的产气效果。【目的】由于煤系叠合型储层层间岩石力学性质与物性差异大，流体运移规律较单一储层开发更为复杂，开展数值模拟研究是解决该问题的有效方法之一。【方法】以黔西地区龙潭组典型煤层-砂岩-泥岩互层型储层为研究对象，考虑叠合型储层的基质收缩效应、有效应力作用以及层间流体流动对储层流体运移规律以及渗透率等储层物性参数的影响，建立煤系叠合型气藏流固耦合数学模型，开展煤系气生产数值模拟，分析不同储层组合排采下储层孔隙压力、基质含气量、渗透率等叠合型储层特征参数的演化规律以及层间流动差异对产气效果的影响。【结果】与单层排采相比，（煤＋泥页岩）排采、（煤＋砂岩）排采、全层段排采下，累积产气量分别提高了1.26倍、1.42倍、1.62倍；四种储层组合排采下均存在层间能量与物质传递；煤、砂岩和泥页岩储层在不同储层组合排采下，储层孔隙压力与传导方向、基质含气量以及渗透率比例均存在明显差异。【结论】全层段的储层组合排采下产气效果最好，砂岩层中游离态甲烷更易产出，有效减弱储层间垂向孔隙压差的影响，更有利于叠合型储层孔隙压力径向传导，促进煤与泥页岩基质中甲烷解吸，增强基质收缩作用，促使煤与泥页岩储层渗透率回弹，从而提高整体产气量。
Production simulation of typical types of the coal measure superimposed reservoir：A case study on Longtan Formation, Western Guizhou
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Abstract: Abstract: In the process of coal measure superimposed reservoir development, the reservoir combination affects the gas production effect of coal measure gas wells. [Objective] Owing to the large differences in rock mechanics and physical properties between coal measure superimposed reservoirs, the fluid migration law is more complicated than that of single reservoir development. Numerical simulation is one of the effective methods to solve this problem. [Methods] Taking the typical coal-sandstone-shale interbedded reservoir of Longtan Formation in western Guizhou as the research object, considering the matrix contraction effect, effective stress effect, and the influence of interlayer fluid flow on reservoir fluid migration, as well as permeability and other physical parameters, a fluid-solid coupling mathematical model of the coal measure gas reservoir is established to conduct numerical simulations of coal measure gas production. The evolution of reservoir characteristic parameters such as pore pressure, matrix gas content, and permeability, as well as the impact of interlayer flow variation on gas production under different reservoir combination drainage scenarios, are analyzed. [Results] Compared with single-layer drainage, cumulative gas production is increased by 1.26 times, 1.42 times and 1.62 times respectively under (coal + shale) drainage, (coal + sandstone) drainage and entire reservoir drainage.There is interlayer energy and material transfer under the four kinds of reservoir combination drainage.There are obvious differences in pore pressure, conductivity direction, matrix gas content and permeability ratio of coal, sandstone and shale reservoirs under different reservoir combination drainage. [Conclusions] The gas production effect is the best in the reservoir combination drainage of the entire reservoir, and the free methane in the sandstone reservoir is easier to produce, which effectively weakens the influence of vertical pore pressure difference between reservoirs, and is more conducive to the radial conduction of pore pressure in the superimposed reservoir, promoting the methane desorption in the coal and shale matrix, enhancing the matrix shrinkage, promoting the permeability rebound of the coal and shale reservoir, and thereby increasing the overall gas production.