页岩微—纳米孔隙及介质界面气体赋存相态分子动力学模拟

发布时间：2018-06-08 13:49

本文选题：页岩 + 微-纳米孔隙　；参考：《东北石油大学》2017年硕士论文

【摘要】：以页岩气为代表的非常规油气资源潜力巨大,受到国内外的广泛重视,成为全球油气勘探的热点。我国页岩气资源非常丰富,估计储量可达数十万亿立方米,是常规天然气的几倍。因此在常规油气能源供应日益紧张的情况下,针对页岩气的勘探、开发展开研究,可为我国改善油气能源结构、解决能源潜在威胁提供新的途径。页岩储层的孔隙结构对页岩气的储集特性具有非常重要的影响。微-纳米孔隙是页岩气赋存的重要空间,探究甲烷在页岩微-纳米孔隙中赋存状态和赋存密度对页岩气藏储气量评估和开采具有重要的意义。本论文以重庆市涪陵地区焦页1井(JY1)典型页岩样品为研究对象,利用其地层环境,在Materials Studio软件中构建出不同吸附基质类型(有机质、脆性矿物、黏土矿物)的吸附模型,并在吸附模型中构建出不同类型孔洞结构(矩形孔洞和三角孔洞),采用分子动力学方法研究甲烷在不同形状及不同基质类型的模型中的吸附过程。通过分层统计方法确定甲烷在不同基质类型、不同孔洞类型和不同位置的甲烷密度分布,再利用径向分布函数探究甲烷吸附微观机理。结果表明:在压强为30MPa,温度为328K条件下,同一种模型中甲烷吸附均出现分层现象,甲烷在狭缝吸附和孔洞内吸附量有一定的差异,孔洞内的甲烷密度基本上大于狭缝中游离甲烷的密度,并且孔洞内的甲烷状态更趋近于液态,矩形孔洞内甲烷吸附密度值和三角孔洞内甲烷吸附密度值略有差异。在相同条件下,不同类型的吸附模型中,甲烷吸附出现的分层现象在不同位置的具体值略有差异,有机质模型中含气总量比脆性矿物模型中含气量高。最后借助扫描电镜采集JY1井2415米深岩石样本图像,识别出有机质孔隙,根据石墨吸附模型计算出不同位置的甲烷吸附密度,在页岩样品的微观结构图中勾勒出孔隙的轮廓边界,并沿着边界区域赋予不同的甲烷吸附量,计算出页岩实际储层的含气量,计算结果与实际现场解析量值接近。因此利用微观模拟方法来评价页岩气宏观含气量具有指导作用。
[Abstract]:The potential of unconventional oil and gas resources, represented by shale gas, is huge, which has been paid more and more attention at home and abroad, and has become a hot spot in oil and gas exploration all over the world. China is rich in shale gas, with estimated reserves of several trillion cubic meters, several times as much as conventional natural gas. Therefore, under the condition of increasing shortage of conventional oil and gas energy supply, the research on shale gas exploration and development can provide a new way to improve the oil and gas energy structure and solve the potential energy threat in China. The pore structure of shale reservoir has a very important effect on the reservoir characteristics of shale gas. Micro-nano porosity is an important space for shale gas occurrence. It is of great significance to explore the occurrence state and density of methane in shale micro-nano pores for the evaluation and exploitation of gas storage in shale gas reservoirs. In this paper, the typical shale samples of Jiaoye 1 well JY1 in Fuling area of Chongqing were studied. By using their stratigraphic environment, the adsorption models of different adsorptive matrix types (organic matter, brittle minerals, clay minerals) were constructed in Materials Studio software. Different types of pore structures (rectangular and triangular) were constructed in the adsorption model. The adsorption process of methane in the models with different shapes and different matrix types was studied by molecular dynamics method. The density distribution of methane in different matrix types, different pore types and different locations was determined by stratified statistical method, and the microscopic mechanism of methane adsorption was explored by radial distribution function. The results show that under the pressure of 30MPa and the temperature of 328K, the adsorption of methane in the same model is stratified, and the amount of methane adsorbed in the slit is different from that in the pore. The density of methane in the pore is basically higher than that in the free methane in the slit, and the methane state in the pore is closer to the liquid state. The adsorption density of methane in the rectangular cavity is slightly different from that in the triangle hole. Under the same conditions, the stratification of methane adsorption in different types of adsorption models is slightly different in different locations, and the total gas content in organic matter model is higher than that in brittle mineral model. Finally, 2415 meters deep rock samples of JY1 well were collected by scanning electron microscope, organic pores were identified, methane adsorption density at different locations was calculated according to graphite adsorption model, and the outline boundary of pores was drawn in the microstructural diagram of shale samples. Along the boundary area, different methane adsorption amounts are assigned to calculate the gas content of the shale reservoir, and the calculated results are close to the actual analytical values in the field. Therefore, the microscopic simulation method can be used to evaluate the macroscopic gas content of shale gas.
【学位授予单位】：东北石油大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：P618.13

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